MCQ Questions Archives

Biology MCQs for Class 12 with Answers Chapter 3 Human Reproduction

July 17, 2020 by Kishen

Free PDF Download of CBSE Biology Multiple Choice Questions for Class 12 with Answers Chapter 3 Human Reproduction. Biology MCQs for Class 12 Chapter Wise with Answers PDF Download was Prepared Based on Latest Exam Pattern. Students can solve NCERT Class 12 Biology Human Reproduction MCQs Pdf with Answers to know their preparation level.

Human Reproduction Class 12 Biology MCQs Pdf

1. Select the correct sequence of stages of spermatogenesis in a human male.
(a) Spermatogonium → Spermatids → Spermatocytes → Spermatozoa
(b) Spermatogonium → Spennatocytes → Spermatids → Spermatozoa
(c) Spermatids → Spermatogonium → Spermatocytes → Spermatozoa
(d) Spermatocytes → Spermatogonium → Spermatids → Spermatozoa

Answer

Answer: b

2. Vas deferens receives the duct of seminal vesicle and forms the
(a) epididymis
(b) urethra
(c) ejaculatory duct
(d) urethral meatus

Answer

Answer: c

3. How many functional sperms and how many ova will be formed by a primary spermatocyte and a primary oocyte, respectively?
(a) One, One
(b) One, Four
(c) Four, One
(d) Four, Four

Answer

Answer: c

4. Proliferative phase of menstrual cycle, is also called
(a) follicular phase
(b) luteal phase
(c) secretory phase
(d) ovulatory phase

Answer

Answer: a

5. Ovulation occurs under the influence of
(a) follicle-stimulating hormone
(b) luteinising hormone
(c) progesterone
(d) estrogen.

Answer

Answer: b

6. There is no cell division involved in
(a) spermatogenesis
(b) oogenesis
(c) embryogenesis
(d) spermiogenesis

Answer

Answer: d

7. It The cell division in secondary oocyte is suspended at
(a) Anaphase II
(b) Metaphase II
(c) Prophase II
(d) Telophase II

Answer

Answer: b

8. After the release of the secondary oocyte, the Graafian follicle develops into
(a) corpus callosum
(b) corpus albicans
(c) corpus luteum
(d) primary follicle

Answer

Answer: c

9. The outermost layer of a blastocyst is called
(a) ectoderm
(b) mesoderm
(c) endoderm
(d) trophoblast

Answer

Answer: d

10. Urethral meatus refers to the [NCERT Exemplar]
(a) urinogenital duct
(b) opening of vas deferens into urethra
(c) external opening of the urinogenital duct
(d) muscles surrounding the urinogenial duct

Answer

Answer: c

11. Morula is a developmental stage [NCERT Exemplar]
(a) between the zygote and blastocyst
(b) between the blastocyst and gastrula
(c) after the implantation
(d) between implantation and parturition

Answer

Answer: a

12. Spermiation is the process of the release of
sperms from [NCERT Exemplar]
(a) seminiferous tubules
(b) vas deferens
(c) epididymis
(d) prostate gland

Answer

Answer: a

13. Which of the following hormones prepares the uterus for implantation?
(a) Progesterone
(b) FSH
(c) Estrogen
(d) LH

Answer

Answer: a

14. The cell which undergoes meiosis I during spermatogenesis, is the
(a) spermatogonium
(b) spermatid
(c) primary spermatocyte
(d) secondary spermatocyte

Answer

Answer: c

15. Seminal plasma, the fluid part of semen is formed by
(a) seminal vesicle and bulbourethral gland.
(b) bulbourethral gland and prostate.
(c) prostate and seminal vesicle.
(d) seminal vesicles, prostate and bulbourethral gland.

Answer

Answer: d

16. The secondary oocyte completes its meiosis II when a sperm comes in contact with it and forms a large cell, the ______ and a second polar body,

Answer/Explanation

Answer:
Explaination: Ootid

17. The gonadotropin-releasing hormone (GnRH) from the _____ initiates spermatogenesis at puberty.

Answer/Explanation

Answer:
Explaination: Hypothalamus

18. The first movements of the foetus and appearance of hair on the head are observed during the _____ month of pregnancy.

Answer/Explanation

Answer:
Explaination: Fifth.

19. The menstrual phase is followed by _____ phase.

Answer/Explanation

Answer:
Explaination: Menarche.

20. _____ refers to the onset of menstruation at puberty.

Answer/Explanation

Answer:
Explaination: Follicular/Proliferative.

21. The outermost thin membranous part of uterine wall is called ______ .

Answer/Explanation

Answer:
Explaination: Menarche.

22. The part of the fallopian tube, which is closer to the ovary and is funnel-shaped, is called ______ .

Answer/Explanation

Answer:
Explaination: Perimetrium.

23. The cells formed as a result of cleavage of the zygote, are called ______ .

Answer/Explanation

Answer:
Explaination: Blastomeres.

24. The placenta is connected to the embryo through _____ .

Answer/Explanation

Answer:
Explaination: Umbilical cord.

25. The process of delivery of the foetus, is called

Answer/Explanation

Answer:
Explaination: Parturition.

Directions (Q26 and Q27): Match Column I with Column II.
26.

Column I	Column II
Cleavage	1. Outer layer of the blastocyst that attaches to the endometrium during implantation.
Implantation	2. Mitotic divisions of the zygote in quick succession.
Inner cell mass	3. Embedding of the blastocyst in the endometrium of uterus.
Troph oblast	4. Release of secondary oocyte from the ovary.
	5. Group of cells attached to one end of trophoblast that differentiate into embryo proper.

Answer/Explanation

Answer:
Explaination: A – 2, B – 3, C – 5, D – 1

27.

Column I	Column II
A. Acrosome	1. Motility of sperm towards the egg.
B. Head	2. Powerhouse of the sperm; contains a number of mitochondria.
C. Tail	3. Contains the genetic material.
D. Middle piece	4. Contains enzymes to dissolve egg envelopes

Answer/Explanation

Answer:
Explaination: A – 4, B – 3, C – 1, D – 2

28. The finger-like projections, called fimbriae, help in the collection of ovum into the fallopian tube following ovulation. [True/False]

Answer/Explanation

Answer:
Explaination: True.

29. Endometrium undergoes cyclical changes and help in uterine movements. [True/False]

Answer/Explanation

Answer:
Explaination: False.

30. Oxytocin, necessary for parturition, is secreted by the fully-developed foetus and the placenta. [True/False]

Answer/Explanation

Answer:
Explaination: False.

31. The finger-like projections that appear on the trophoblast following implantation, are called chorionic villi. [True/False]

Answer/Explanation

Answer:
Explaination: True.

32. Relaxin is the hormone secreted by the placenta. [True/False]

Answer/Explanation

Answer:
Explaination: False.

Directions (Q33 to Q37): Mark the odd one in each of the following groups.

33. Fimbriae, Labia minora, Infundibulum, Isthmus.

Answer/Explanation

Answer:
Explaination: Labia minora

34. Rete testis, Vasa efferentia, Epididymis, Ampulla

Answer/Explanation

Answer:
Explaination: Ampulla

35. Bulbourethral gland, Prostate. Seminal vesicle, Seminiferous tubule.

Answer/Explanation

Answer:
Explaination: Seminiferous tubules

36. Oogonia, Spermatogonia, Zygote, Ootid

Answer/Explanation

Answer:
Explaination: Ootid

37. Luteinizing hormone, Progesterone, Chorionic gonadotropin, Estrogen

Answer/Explanation

Answer:
Explaination: Luteinizing hormone.

38. Name the cells that nourish the germ cells in the testes. Where are these cells located in the testes? [AI2013C]

Answer/Explanation

Answer:
Explaination: Sertoli cells; they are found in the inner lining of seminiferous tubules.

39. How is a primary spennatocyte different from a secondary spermatocyte?

Answer/Explanation

Answer:
Explaination:
– A primary spermatocyte is diploid and has 46 chromosomes; it undergoes meiosis I and forms two secondary spermatocytes.
– A secondary spermatocyte is haploid and has 23 chromosomes; it undergoes meiosis II and forms two spermatids.

40. Where is acrosome present in humans? Write its function. [AI 2012]

Answer/Explanation

Answer:
Explaination:
– Acrosome is present at the anterior end of the head region of a human sperm.
– It contains enzymes that help in dissolving the envelopes (zona pellucida and plasma membrane) of ovum to facilitate entry of sperm into the cyloplasm of the ovum.

41. Why is the middle piece of human sperm considered as ‘powerhouse of the sperm’? [HOTS]

Answer/Explanation

Answer:
Explaination: Middle piece contains numerous mitochondria, which produce energy for the movement of sperm for fertilisation; so it is called the power house.

42. What is semen?

Answer/Explanation

Answer:
Explaination: Seminal plasma (secreted by the male reproductive glands) along with the spermatozoa, constitute semen.

43. Mention the difference between spermiogen- esis and spermiation, [Delhi 2012]

Answer/Explanation

Answer:
Explaination:
– Spermiogenesis is the process of , transformation of spermatids into
flagellated spermatozoa.
– Spermiation is the process of release . of spermatozoa from the seminiferous tubules of the testes into the ducts.

44. How many primary follicles are left in each ovary in a human female at puberty’?

Answer/Explanation

Answer:
Explaination: 60,000 – 80,000 primary follicles are left in each ovary.

45. List the changes the primary oocyte undergoes in the tertiary follicular stage in the human ovary. [Foreign 2011]

Answer/Explanation

Answer:
Explaination: The primary oocyte grows in size and completes meiosis I and forms a larger cell, the secondary oocyte and a smaller cell, the first polar body.

46. Write the physiological reason, why a woman generally cannot conceive a child after 50 years of age. [AI 2013C]

Answer/Explanation

Answer:
Explaination:
– Menopause, i.e. stoppage of menstrual cycles occurs around 50 years of age; since no ovulation occurs, the woman cannot conceive after this age.

47. Not all copulations lead to pregnancy. Give reason. [HOTS]

Answer/Explanation

Answer:
Explaination:
– The sperm and ovum must reach the ampullary-isthmic junction at the same time, if fertilisation has to occur.
– If the sperms and the ovum are not transported simultaneously to the site of fertilisation, no fertilisation occurs, though copulation has occurred.

48. How does the sperm penetrate through the zona pellucida in human ovum? [Delhi 2013C]

Answer/Explanation

Answer:
Explaination: The sperm penetrates through zona pellucida with the help of secretions from its acrosome.

49. How is the entry of only one sperm and not many, ensured into an ovum during fertilisation in humans? [AI 2012]
Or
During fertilization, hundreds of sperm cells are in the vicinity of an egg cell; but only- one sperm enters the ovum. How is this achieved? [HOTS]

Answer/Explanation

Answer:
Explaination: The changes induced in the zona pellucida of the ovum by the sperm coming in contact with it, block the entry of any other sperm and ensures the entry of only one sperm.

50. What is cleavage?

Answer/Explanation

Answer:
Explaination: Cleavage refers to the rapid mitotic divisions that occur in the zygote.

51. Name the embryonic stage that gets implanted in the uterine wall of human female.

Answer/Explanation

Answer:
Explaination: Blastocyst gets implanted.

52. Identify the figure given and the part labelled “A”.[AI 2011]
Biology MCQs for Class 12 with Answers Chapter 3 Human Reproduction 1

Answer/Explanation

Answer:
Explaination:
– It is a mammalian blastocyst.
– A is trophoblast.

53. Mention the function of trophoblast in human embryo. [Delhi 2011]

Answer/Explanation

Answer:
Explaination: Trophoblast forms chorionic villi, which become part of the placenta.

54. What are chorionic villi?

Answer/Explanation

Answer:
Explaination: Chorionic villi are the finger-like projections formed by the trophoblast immediately after implantation; they form the foetal part of the placenta.

55. How is the first sign of growing foetus noticed?

Answer/Explanation

Answer:
Explaination: The first sign of growing foetus is noticed by listening to the heart sounds through a stethoscope.

56. What is meant by gestation period?

Answer/Explanation

Answer:
Explaination: The time period between implantation and parturition, when the embryo completes its growth and development, is called gestation period.

57. State where the signals for parturition arise from, in humans. [AI 2017C]

Answer/Explanation

Answer:
Explaination: The signals for parturition arise from the fully-developed foetus and the placenta.

58. What stimulates the pituitary to release the hormone responsible for parturition? Name the hormone. [AI 2011]

Answer/Explanation

Answer:
Explaination:
– The foetal ejection reflex stimulates the release of hormone for parturition.
– Oxytocin is the hormone.

59. Define Lactation.

Answer/Explanation

Answer:
Explaination: Lactation is the process of feeding the new { bom baby with the milk secreted by the mammary glands.

60. How does the sperm penetrate through the zone pellucida in human ovum?

Answer/Explanation

Answer:
Explaination: The sperm penetrates through zona pellucida with the help of the secretions from the acrosome.

We hope the given Biology MCQs for Class 12 with Answers Chapter 3 Human Reproduction will help you. If you have any query regarding CBSE Class 12 Biology Human Reproduction MCQs Pdf, drop a comment below and we will get back to you at the earliest.

Biology MCQs for Class 12 with Answers Chapter 4 Reproductive Health

July 17, 2020 by Kishen

Free PDF Download of CBSE Biology Multiple Choice Questions for Class 12 with Answers Chapter 4 Reproductive Health. Biology MCQs for Class 12 Chapter Wise with Answers PDF Download was Prepared Based on Latest Exam Pattern. Students can solve NCERT Class 12 Biology Reproductive Health MCQs Pdf with Answers to know their preparation level.

Reproductive Health Class 12 Biology MCQs Pdf

1. Which of the following is hormonereleasing?
(a) Multiload 375
(b) LNG-20
(c) Lippes loop
(d) Cu 7

Answer

Answer: b

2. Which among the following is commonly called withdrawal method?
(a) Lactational amenorrhoea
(b) Coitus interruptus
(c) Periodic abstinence
(d) Rhythm method

Answer

Answer: b

3. In which of the following ARTs, does in vivo fertilisation occur?
(a) ZIFT
(b) GIFT
(c) ICSI
(d) IVF

Answer

Answer: b

4. Surgical methods, also called sterilisation techniques are fool-poof methods be prevent pregnancy. But, it is the last option for many couples, because
(a) it is nearly irreversible.
(b) of lack of sufficient facilities in many parts of the country.
(c) of fear that it will reduce sexual drive.
(d) all of these

Answer

Answer: d

5. Emergency contraceptives are effective if
used within [NCERT Exemplar]
(a) 72 hrs of coitus.
(b) 72 hrs of ovulation.
(c) 72 hrs of menstruation.
(d) 72 hrs of implantation.

Answer

Answer: a

6. Condoms are one of the most popular contraceptives because of the following reasons [NCERT Exemplar]
(a) these are effective barriers for insemination.
(b) they do not interfere with coital act.
(c) these help in reducing the risk of STDs.
(d) all of the above.

Answer

Answer: d

7. Intensely lactating mothers do not generally conceive due to the [NCERT Exemplar]
(a) suppression of gonadotropins.
(b) hyper secretion of gonadotropins.
(c) suppression of gametic transport.
(d) suppression of fertilisation.

Answer

Answer: a

8. The method of directly injecting a spenn into ovum in assisted reproductive, technology is called [NCERT Exemplar]
(a) GIFT
(b) ZIFT
(c) ICSI
(d) ET

Answer

Answer: c

9. The oral contraceptive pills mainly contain the hormones
(a) estrogen and luteinising hormone.
(b) progesterone and estrogen.
(c) estrogens and follicle-stimulating hormone.
(d) progesterone and follicle-stimulating hormone.

Answer

Answer: b

10. Diaphragms are the contraceptive devices used by females. Choose the correct option about them.
(a) They are reusable.
(b) They block the entry of sperms.
(e) They are placed to cover the cervix.
(d) All of these.

Answer

Answer: d

11. ZIFT is transfer of
(a) zygote into fallopian tube.
(b) a mixture of sperms and ova into the fallopian tube.
(c) a mixture of sperms and ova into the uterus.
(d) embryo into the uterus.

Answer

Answer: a

12. ‘Sahelr is a/an
(a) oral contraceptive for females.
(b) surgical/sterilisation method for females.
(c) diaphragm for females.
(d) surgical/sterilisation method for males.

Answer

Answer: a

13. _______ is the sterilisation procedure carried out in males.

Answer/Explanation

Answer:
Explaination: Vasectomy.

14. The incidences of STPs are reported to be very high among persons in the age group of _____ years.

Answer/Explanation

Answer:
Explaination: 15 – 24.

15. The world population was around ______ in 1900.

Answer/Explanation

Answer:
Explaination: 2 billion/2000 million.

16. According to the 2001 census report, the population growth rate in India is ______ per year.

Answer/Explanation

Answer:
Explaination: 17/1000 or 1.7 per cent.

17. ______ methods work on the principle of avoiding the chances of meeting of ovum and sperm.

Answer/Explanation

Answer:
Explaination: Barrier.

18. ______ is the oral contraceptive for female containing non-steroidal preparation.

Answer/Explanation

Answer:
Explaination: Saheli.

19. The statutory ban on _____ is to legally check the female foeticide.

Answer/Explanation

Answer:
Explaination: Amniocentesis.

20. Day ______ of the menstrual cycle are called fertile period.

Answer/Explanation

Answer:
Explaination: 10-17.

21. Embryo with more than 32 blastomeres is transferred into the _______ .

Answer/Explanation

Answer:
Explaination: Uterus.

22. Surgical methods of contraception are highly effective but their _______ is poor.

Answer/Explanation

Answer:
Explaination: Reversibility.

Directions (Q23 and Q24): Match the items of Column I with those of Column II.
23.

Column 1	Column 11
A. Copper – releasing IUD	1. Sterilisation in males.
B. Hormone – releasing IUD	2. Progesterone- estrogen combination.
C. Vasectomy	3. Progestasert.
D. Oral contraceptive	4. Multiload 375.

Answer/Explanation

Answer:
Explaination: A – 4, B – 3, C – 1, D – 2

24.

Column I	Column II
A. Lactational amenorrhoea	1. Directly injecting a sperm into the ovum.
B. ICSI	2. Suppressing ovulation and implantation.
C. Tubectomy	3. Suppression of gonadotropins.
D. Oral contraceptive	4. Blocking the transport of gametes.
	5. Implant under the skin.

Answer/Explanation

Answer:
Explaination: A – 3, B – 1, C – 4, D – 2

25. Contraceptive pills prevent ovulation and implantation. [True/False]

Answer/Explanation

Answer:
Explaination: True.

26. MTPs are considered relatively safe during the first 18 weeks of pregnancy. [True/False]

Answer/Explanation

Answer:
Explaination: False.

27. Hepatitis-B, AIDS and genital herpes are the STDs that can be cured. [True/False]

Answer/Explanation

Answer:
Explaination: False.

28. Sterilisation process in males, is called vasectomy and that in females, is called tubectomy. [True/False]

Answer/Explanation

Answer:
Explaination: True.

29. Saheli is an imported oral pill. [True/False]

Answer/Explanation

Answer:
Explaination: False.

Directions (Q30 to Q33): Mark the odd one in each of the following groups.
30. Diaphragm, Vaults, Progestasert, Cervical caps

Answer/Explanation

Answer:
Explaination: Progestasert.

31. Coitus interruptus, Vasectomy, Periodic abstinence, Lactational amenorrhoea.

Answer/Explanation

Answer:
Explaination: Vasectomy.

32. Cu 7, CuT, LNG-20, Multiload

Answer/Explanation

Answer:
Explaination: LNG-20.

33. ZIFT, GIFI, IUI, MTP

Answer/Explanation

Answer:
Explaination: MTP.

34. What is meant by reproductive health according to WHO?

Answer/Explanation

Answer:
Explaination: According to WHO, reproductive health means a total, well-being in physical, emotional, behavioural and social aspects of reproduction.

35. Mention one positive and one negative application of amniocentesis. [Delhi 2010]

Answer/Explanation

Answer:
Explaination:
Positive application:
– Any genetic disorder of the foetus can be detected.
Negative application:
– It is misused for sex determination and female foeticide.

36. Government of India has raised the marriageable age of female to 18 years and of males to 21 years. Suggest any two more measures adopted by Government for the purpose. [CBSE Sample Paper 2016]

Answer/Explanation

Answer:
Explaination:
The other methods include:
– Motivation to have smaller families by using various contraceptive methods.
– Advertisements in the media and posters showing a happy couple with two children with a slogan ‘Hum Do, Hamare Do’.
– Incentives given to the couples with small families. (any two)

37. State one reason why breast feeding the baby acts as a natural contraceptive, for the mother? [AI2014C; HOTS]

Answer/Explanation

Answer:
Explaination:
(i) The events of menstrual cycle are absent during the period of intense lactation.
(ii) In the absence of ovulation, there is no question of fertilisation and conception.

38. Why is the period between day 10 and 17 of the menstrual cycle, called ‘fertile period’? [HOTS]

Answer/Explanation

Answer:
Explaination: Ovulation occurs during this period and chances of fertilisation are high; hence this period is called ‘fertile period’.

39. What is the principle behind the barrier methods of birth control?

Answer/Explanation

Answer:
Explaination: In these methods, the ovum and sperms are prevented from physically meeting each other.

40. Name any two barriers used by human females for birth control.

Answer/Explanation

Answer:
Explaination: Cervical caps, diaphragms, vaults, (any two)

41. What are the advantages of using condoms?

Answer/Explanation

Answer:
Explaination:
(i) Condoms act as barriers for the meeting of sperm and ovum and prevent conception.
(ii) They also protect the user from contracting STDs.

42. Name an IUD that you would recommend to promote the cervix hostility to the sperms. [Delhi 2014C]

Answer/Explanation

Answer:
Explaination: Hormone-releasing IUDs like LNG-20 or progestasert.

43. Mention any two events that are inhibited by the intake of oral contraceptive pills to prevent pregnancy in humans.

Answer/Explanation

Answer:
Explaination: Ovulation and implantation.

44. How can pregnancy due to rape or casual unprotected intercourse be prevented?

Answer/Explanation

Answer:
Explaination:
Pregnancy due to rape or casual unprotected intercourse can be prevented by
(i) administration of progestogens or progestogen-estrogen combination within 72 hours of coitus.
(ii) administration of IUDs within 72 hours of coitus.

45. Why is tubectomy considered a contraceptive method? [Foreign 2010]

Answer/Explanation

Answer:
Explaination:
In tubectomy, the surgical intervention blocks the transport of ova and hence the conception; so it is considered a contraceptive method.

46. What is MTP?

Answer/Explanation

Answer:
Explaination: MTP refers to the intentional or voluntary termination of pregnancy before full term under the care of a medical practitioner.

47. When was MTP legalised by the Indian government?

Answer/Explanation

Answer:
Explaination: In the year 1971.

48. Our government has intentionally imposedstrict conditions for MTP in our country. Justify giving a reason. [Delhi 2017]

Answer/Explanation

Answer:
Explaination: The restrictions are mainly to check the indiscriminate and illegal female foeticides.

49. Name two sexually transmitted diseases caused by bacteria.
Or
Name two curable STDs.

Answer/Explanation

Answer:
Explaination: Syphilis and gonorrhoea.

50. Name two STDs which can be transmitted through contaminated blood.
Or
Name two sexually transmitted diseases that do not specifically affect the reproductive organs.

Answer/Explanation

Answer:
Explaination: Hepatitis B and AIDS.

51. Give two reasons why a person infected with a venereal disease does not go for timely detection and treatment of it.

Answer/Explanation

Answer:
Explaination:
(i) The early symptoms of venereal diseases are less significant and cannot be detected.
(ii) The social stigma attached to the disease.

52. Mention the age group where STDs are reported to be very high.

Answer/Explanation

Answer:
Explaination: 15-24 years is the age group.

53. Name two STDs that are not curable.

Answer/Explanation

Answer:
Explaination: AIDS, genital herpes, Hepatitis-B. (any two)

54. Mention the primary aim of the ARTs.

Answer/Explanation

Answer:
Explaination: The primary aim oftheARTs is the diagnosis and corrective treatment of the causes of infertility and enable the couples to have children.

55. Name any two assisted reproductive technologies that help infertile couples to have children. [Delhi 2012C]

Answer/Explanation

Answer:
Explaination:
(i) Test Tube Baby Programme
(ii) Gamete Intra-Fallopian Transfer (GIFT)
(iii) Intra-Cytoplasmic Sperm Injection (ICSI)
(iv) Artificial Insemination. (any two)

We hope the given Biology MCQs for Class 12 with Answers Chapter 4 Reproductive Health will help you. If you have any query regarding CBSE Class 12 Biology Reproductive Health MCQs Pdf, drop a comment below and we will get back to you at the earliest.

Biology MCQs for Class 12 with Answers Chapter 5 Principles of Inheritance and Variation

July 17, 2020 by Kishen

Free PDF Download of CBSE Biology Multiple Choice Questions for Class 12 with Answers Chapter 5 Principles of Inheritance and Variation. Biology MCQs for Class 12 Chapter Wise with Answers PDF Download was Prepared Based on Latest Exam Pattern. Students can solve NCERT Class 12 Biology Principles of Inheritance and Variation MCQs Pdf with Answers to know their preparation level.

Principles of Inheritance and Variation Class 12 Biology MCQs Pdf

1. When ‘Aa’ is crossed with ‘aa’, (A is dominant over a)
(a) all the offspring will have dominant phenotype.
(b) all the offspring will have recessive phenotype.
(c) 50% of offspring will have dominant phenotype and 50% will have recessive phenotype.
(d) 75% of offspring will have dominant phenotype and 50% will have recessive phenotype.

Answer

Answer: c

2. A heterozygous violet-flowered pea plant is crossed to another homozygous violet- flowered pea plant. What percent of the progeny plants will have the recessive trait, i.e., white flowers?
(a) 0%
(b) 25%
(c) 50%
(d) 75%

Answer

Answer: a

3. From a cross AABb x aaBb, the genotypes AaBB : AaBb : Aabb will be obtained in the ratio
(a) 1:1:2
(b) 1:2:1
(c) 2:1:1
(d) 2:1:2

Answer

Answer: b

4. The possibility of all genotypes of offspring in a genetic cross is calculated by a graphical representation which was developed by
(a) Komberg
(b) T.H. Morgan
(c) Gregor Mendel
(d) Reginald Punnett

Answer

Answer: d

5. A woman with normal vision has a colorblind father. She marries a colourblind man. What proportion of their children will be colourblind?
(a) 0%
(b) 25%
(c) 50%
(d) 100%

Answer

Answer: c

6. Study the pedigree chart given

Select the correct option about the conclusion.
(a) It is a sex-linked recessive trait.
(b) It is an autosomal recessive trait.
(c) It is an autosomal dominant trait.
(d) It is a sex-linked dominant trait.

Answer

Answer: b

7. Mother and father of a person with ‘O’ blood group have ‘A’ and ‘B’ blood group respectively. What would be the genotype of both mother and father? [NCERT Exemplar]
(a) Mother is homozygous for ‘A’ blood group and father is heterozygous for ‘B’.
(b) Mother is heterozygous for ‘A’ blood group and father is homozygous for ‘B’.
(c) Both mother and father are heterozygous for ‘A’ and ‘B’ blood group, respectively.
(d) Both mother and father are homozygous for ‘A’ and ‘B’ blood group, respectively.

Answer

Answer: c

8. The inheritance pattern of a gene over generations among humans is studied by the pedigree analysis. Character studied in the pedigree analysis is equivalent to: [NCERT Exemplar]
(a) Quantitative trait.
(b) Mendelian trait.
(c) Polygenic trait.
(d) Maternal trait.

Answer

Answer: b

9. Occasionally, a single gene may express more than one effect. The phenomenon is called: [NCERT Exemplar]
(a) multiple allelism
(b) mosaicism
(c) pleiotropy
(d) polygeny.

Answer

Answer: c

10. Conditions of a karyotype 2n ± 1 and 2n ± 2 are called: [NCERT Exemplar]
(a) Aneuploidy
(b) Polyploidy
(c) Allopolyploidy
(d) Monosomy.

Answer

Answer: a

11. If a genetic disease is transferred from a phenotypically normal but carrier female to only some of the male progeny, the disease is: [NCERT Exemplar]
(a) Autosomal dominant
(b) Autosomal recessive
(c) Sex-linked dominant
(d) Sex-linked recessive.

Answer

Answer: d

12. In a dihybrid cross, if you get 9:3:3:1 ratio it denotes that: [NCERT Exemplar]
(a) The alleles of two genes are interacting with each other.
(b) It is a multigenic inheritance.
(c) It is a case of multiple allelism.
(d) The alleles of two genes are segregating independently.

Answer

Answer: d

13. In sickle cell anaemia glutamic acid is ’» replaced by valine. Which one of the following triplets codes for valine? [NCERT Exemplar]
(a) G G G
(b) A A G
(c) G A A
(d) G U G

Answer

Answer: d

14. Which of the following traits studied by Mendel in garden pea is a dominant trait?
(a) Terminal flowers.
(b) Inflated pod.
(c) Green colour of seed.
(d) Yellow colour of pod.

Answer

Answer: b

15. If a haemophilic woman marries a normal man,
(a) all their children will be normal.
(b) all their sons will be haemophilic.
(c) all their daughters will be haemophilic.
(d) 50% sons and 50% daughters will be haemophilic.

Answer

Answer: b

16. Trisomy of 21 st chromosome in a male, leads to ______ syndrome.

Answer/Explanation

Answer:
Explaination: Down’s.

17. Sex chromosome complement of a female bird is ______ .

Answer/Explanation

Answer:
Explaination: ZW.

18. If three children in a family have blood groups O, AB and A, the genotypes of the parents must be _____ and ____ .

Answer/Explanation

Answer:
Explaination: I^Ai, I^Bi.

19. Mendel’s law of ______ explains the expression of only one form of the trait in F, hybrid.

Answer/Explanation

Answer:
Explaination: Dominance.

20. XO chromosomal abnormality in humans _______ causes syndrome.

Answer/Explanation

Answer:
Explaination: Turner’s.

21. was the first to observe the X-chromosome in a few insects.

Answer/Explanation

Answer:
Explaination: Henking.

22. The physical association between two genes on a chromosome, is termed as _____ by Morgan.

Answer/Explanation

Answer:
Explaination: Linkage.

23. Female heterogamety is observed in

Answer/Explanation

Answer:
Explaination: Birds.

24. Cystic fibrosis and haemophilia are examples of disorders.

Answer/Explanation

Answer:
Explaination: Mendelian.

25. In sickle-cell anaemia, the amino acid, glutamic acid is substituted by in the beta chain of haemoglobin.

Answer/Explanation

Answer:
Explaination: Valine.

26. Match the items in Column I with those in Column II.

Column I	Column II
A. ABO blood group in humans.	1. Polygenic inheritance.
B. Flower colour snapdragon.	2. Mendelian genetic disorder.
C. Human skin colour.	3. Sex-linked Mendelian disorder
D. Phenyl – ketonuria.	4. Incomplete dominance
	5. Multiple allelism.

Answer/Explanation

Answer:
Explaination: A – 5, B – 4, C – 1, D – 2

27. Match the sex-chromosome complements in Column I with the male/female organisms in Column II.

Column I	Column II
A. XO	1. Human male
B. XX	2. Male bird
C. XY	3. Male grasshopper
D. ZZ	4. Female Drosophila
	5, Female bird

Answer/Explanation

Answer:
Explaination: A – 3, B – 4, C – 1, D – 5

28. The recessive trait appears only under homozygous condition. [True/False]

Answer/Explanation

Answer:
Explaination: True.

29. The phenotype of the F₁ hybrid resembles the dominant parent, when there is incomplete dominance. [True/False]

Answer/Explanation

Answer:
Explaination: False.

30. The cross between the F₁ hybrid with a homozygous dominant individual, is called a test cross. [True/False]

Answer/Explanation

Answer:
Explaination: False.

31. Mendel could not have framed the law of independent assortment, if the genes he had studied, showed linkage. [True/False]

Answer/Explanation

Answer:
Explaination: True.

32. 9:3 :3 :1 is the genotypic ratio of a Mendelian dihybrid cross. [True/False]

Answer/Explanation

Answer:
Explaination: True.

Directions (Q33 to Q35): Mark the odd one in each of the following groups.

33. Phenyl ketonuria, Sickle-cell anaemia, Cystic fibrosis, Colourblindness

Answer/Explanation

Answer:
Explaination: Colourblindness.

34. Inflated pods, Terminal flowers, Yellow seeds, Green pods (all in garden pea).

Answer/Explanation

Answer:
Explaination: Terminal flowers.

35. Turner’s syndrome, Klinefelter’s syndrome, Down’s syndrome, Haemophilia.

Answer/Explanation

Answer:
Explaination: Haemophilia.

36. Define inheritance.

Answer/Explanation

Answer:
Explaination: Inheritance is defined as the process by which characters are passed on from one generation to the next.

37. What is genetics?

Answer/Explanation

Answer:
Explaination: Genetics is the branch of science that deals with inheritance and variation of traits.

38. What are true-breeding lines that are used to study inheritance pattern of traits in plants? [Delhi 2014]

Answer/Explanation

Answer:
Explaination: A true-breeding line is one that has undergone continuous self-pollination/inbreeding and shows stable inheritance and expression of a trait for several generations.

39. List any two characters of pea plants used by Mendel in his experiments, other than height of the plant and colour of the seed. [Delhi 2017C]

Answer/Explanation

Answer:
Explaination: Colour of the pod, shape of the pod, colour
of the flower, position of the flower, shape of the seed. (any two)

40. Name two contrasting pod-related traits studied by Mendel, in pea plant experiments. [AI 2011C]

Answer/Explanation

Answer:
Explaination:
– Pod colour: Green pods and yellow pods.
– Pod shape: Inflated pods and constricted pods. (anyone)

41. Mention two contrasting flower-related traits studied by Mendel in pea plant experiments. [AI 2011C]

Answer/Explanation

Answer:
Explaination:
– Flower position: Axial flowers and terminal flowers
– Flower colour: Violet flowers and white flowers. (any one)

42. Mention any two contrasting traits with respect to seeds in pea plants that were studied by Mendel. [AI 2014]

Answer/Explanation

Answer:
Explaination:
– Seed shape: Round and wrinkled.
– Seed colour: Yellow and green, (any one)

43. What is the proof for or what indicates that the characters Mendel studied did not show blending? [HOTS]

Answer/Explanation

Answer:
Explaination: The parental forms of the trait appear without any change in the F₂ generation.

44. What is meant by blending inheritance?

Answer/Explanation

Answer:
Explaination: Blending inheritance is the phenomenon in which the expression of a trait is due to mixing or blending of the parental characters and the trait expressed is in between the two parental forms of the trait; the parental forms of the trait never reappear in the subsequent progenies.

45. State a difference between a gene and an allele. [Delhi 2016]

Answer/Explanation

Answer:
Explaination:
– A gene is a unit of inheritance, which contains information that is required to express a particular trait in an organism.
– An allele is one of the slightly different forms of a gene that codes for a contrasting trait.

46. What is meant by genotype?

Answer/Explanation

Answer:
Explaination: The genetic constitution of an organism, is called its genotype.

47. What is phenotype?

Answer/Explanation

Answer:
Explaination: The observable or external appearance of a character of an organism, is its phenotype.

48. Mention the type of allele which expresses itself only in homozygous condition in an organism. [Foreign 2011]

Answer/Explanation

Answer:
Explaination: Recessive allele.

49. What is a monohybrid cross?

Answer/Explanation

Answer:
Explaination: Monohybrid cross is a cross made between , two individuals of a species, considering the inheritance of the contrasting pair of a single character/trait.

50. Why is a plant with genotype Tt referred to as heterozygous? [HOTS]

Answer/Explanation

Answer:
Explaination: Since the alleles for the contrasting forms of a trait are dissimilar, it is referred to as heterozygous.

51. State the fate of a pair of autosomes during gamete formation. [Delhi 2017]

Answer/Explanation

Answer:
Explaination: The members of a pair of autosomes segregate during gamete formation and enter different gametes.

52. British geneticist R.C. Punnett developed a graphical representation of a genetic cross called ‘Punnett Square’. Mention the possible result this representation predicts of the genetic cross carried. [Delhi 2019]

Answer/Explanation

Answer:
Explaination: This graphical representation predicts the probability of all possible genotypes of offspring in the genetic cross carried out.

53. Write the percentage of the pea plants that would be homozygous recessive in the F₂ generation, when tall F₁ heterozygous pea plants are selfed. [Delhi 2012C]

Answer/Explanation

Answer:
Explaination: 25 per cent.

54. Write the percentage of the pea plants that would be heterozygous tall in the F₂ generation, when the tall heterozygous F₁ pea plants are selfed. [Delhi 2012C]

Answer/Explanation

Answer:
Explaination: 50 per cent.

55. Write the percentage of F₂ homozygous and heterozygous populations in a typical monohybrid cross. [Foreign 2010]

Answer/Explanation

Answer:
Explaination:
Homozygous population – 50 per cent.
Heterozygous population – 50 per cent.

56. When a tall pea plant was self-pollinated, one-fourth of the progeny were dwarf. Give the genotype of the parent and the dwarf progenies. [HOTS]

Answer/Explanation

Answer:
Explaination: Parent – Tt; Dwarf progenies – tt.

57. A garden pea plant
(A) produced inflated, yellow pods and another plant
(B) of the same species produced constricted, green pods. Identity the dominant traits. [Delhi 2012]

Answer/Explanation

Answer:
Explaination: Inflated pods and green pods are dominant traits.

58. A garden pea plant produced axial violet flowers. Another of the same species produced terminal violet flowers. Identify the dominant traits. [AI2012]

Answer/Explanation

Answer:
Explaination: Axial flowers and violet flowers are dominant traits.

59. A garden pea plant produced round, green seeds. Another of the same species produced wrinkled, yellow seeds. Identify the dominant traits. [Foreign 2012]

Answer/Explanation

Answer:
Explaination: Round seeds and yellow seeds are dominant traits.

60. Write the possible genotypes Mendel got, when he crossed F₁ tall pea plant with a dwarf pea plant. [Foreign 2012; HOTS]

Answer/Explanation

Answer:
Explaination: Tt and tt.

61. Mendel observed two kinds of ratios, 3 : 1 and 1 : 2 : 1, in the F2 generation in his experiments on garden pea. Name these two ratios respectively.

Answer/Explanation

Answer:
Explaination:
3 : 1 is the phenotypic ratio of a monohybrid cross.
1 : 2 : 1 is the genotypic ratio of a monohybrid cross.

62. Name the type of cross that would help to find the genotype of a pea plant bearing violet flowers. [AI 2017]

Answer/Explanation

Answer:
Explaination: A test cross with a pea plant bearing white flowers.

63. In a test cross progeny of pea plants, all were bearing violet flowers. Give the genotypes of the parent pea plants. [AI 2012 C; HOTS]

Answer/Explanation

Answer:
Explaination: The genotypes of the parent pea plants are VV and vv.

64. Why in a test cross, did Mendel cross a tall pea plant with a dwarf pea plant only? [Foreign 2012; HOTS]

Answer/Explanation

Answer:
Explaination: Dwarfness is a recessive trait which is expressed only in homozygous condition; so, he was sure of the genotype of the dwarf plant as tt.

65. A cross was carried out between two pea plants showing the contrasting traits of height of the plant. The result of the cross showed 50% of parental characters. Name the type of cross. [CBSE Sample Paper 2018]

Answer/Explanation

Answer:
Explaination: It is a (monohybrid) test cross.

66. Name and state the law of Mendel, which explains the expression of only one of the parental characters in the F, progeny of a monohybrid cross. [HOTS]

Answer/Explanation

Answer:
Explaination: Law of dominance states that in a dissimilar pair of factors, one member of the pair dominates (dominant) the other (recessive).

67. Which law of inheritance of Mendel, is universally acceptable without any exception? State the law. [CBSE Sample Paper 2010; HOTS]

Answer/Explanation

Answer:
Explaination: Law of Segregation states that the members of the allelic pair that remained together in the hybrid, segregate or separate during gametogenesis and enter different gametes.

68. Name the type of inheritance in which the genotypic ratio is the same as the phenotypic ratio. Also give the ratio.

Answer/Explanation

Answer:
Explaination:
– Incomplete dominance is the phenomenon.
– The phenotypic and genotypic ratio of F₂ progeny in a monohybrid cross is 1 : 2 : 1.

69. Name any one plant and its feature that shows the phenomenon of incomplete dominance.

Answer/Explanation

Answer:
Explaination: Snapdragon (Antirrhinum sps) shows incomplete dominance in the inheritance of its flower colour.

70. Give an example of a plant, where the F2 progeny of a monohybrid cross has the same genotypic and phenotypic ratios. [Delhi 2016C]

Answer/Explanation

Answer:
Explaination: Snapdragon (Antirrhinum sp.) shows same genotypic and phenotypic ratios for inheritance of flower colour.

71. Name the respective pattern of inheritance, where Ft phenotype
(a) does not resemble either of the two parents and is in between the two;
(b) resembles only one of the two parents. [AI 2012]

Answer/Explanation

Answer:
Explaination:
(a) Incomplete dominance.
(b) Complete dominance.

72. Write the technical term used in human ABO blood groups for IA, IB and i. [Delhi 2016C]

Answer/Explanation

Answer:
Explaination: Multiple alleles.

73. The gene I that controls the ABO blood grouping in human beings, has three alleles, IA, IB and i.
(a) How many different genotypes are likely to be present in the human population?
(b) Also, how many phenotypes are possibly present? [CBSE Sample Paper 2016]

Answer/Explanation

Answer:
Explaination:
(a) Six different genotypes.
(b) Four phenotypes.

74. Write the codominant alleles in the ABO blood group characteristic of humans.

Answer/Explanation

Answer:
Explaination: IA and IB are codominant alleles.

75. How many kinds of phenotypes would you expect in the F2 generation in a monohybrid cross, exhibiting codominance? [Delhi 2014]

Answer/Explanation

Answer:
Explaination: Three kinds of phenotypes.

76. Multiple allelism can be investigated only in populations. Justify. [HOTS]

Answer/Explanation

Answer:
Explaination: Though a gene exists in more than two allelic forms in multiple allelism, a person can have only two of those alleles, as he has only two sets of homologous chromosomes; so, multiple allelism can be studied only in a population.

77. How is pleiotropy exemplified in Drosophila?

Answer/Explanation

Answer:
Explaination: In Drosophila white eye colour is associated with depigmentation in many other parts of the body; it is due to the pleiotropic effect of a single gene.

78. What is a dihybrid cross?

Answer/Explanation

Answer:
Explaination: A dihybrid cross is a cross made between individuals of a species, considering the inheritance of contrasting pairs of two traits.

79. AaBb was crossed with aabb. What would be the phenotypic ratio of the progeny? Mention the term used to denote this kind of cross. [CBSE Sample Paper 2010]

Answer/Explanation

Answer:
Explaination:
– The phenotypic ratio will be 1 : 1 : 1 : 1. – It is a test cross.

80. A geneticist interested in studying variations and patterns of inheritance in living beings prefers to choose organisms for experiments with shorter life cycle. Provide a reason. [Delhi 2015]

Answer/Explanation

Answer:
Explaination: A number of (successive) generations can be raised in a short time to study the patterns of inheritance.

81. Define linkage.

Answer/Explanation

Answer:
Explaination: Linkage is the phenomenon, where two or more linked genes are always inherited together and their recombination frequency in a dihybrid test cross progeny is less than 50%.

82. In a dihybrid cross carried out by T.H. Morgan in Drosophila, the F₂ ratio deviated from that of Mendel’s dihybrid F₂2 ratio. Give a reason. [AI 2016C]
Or
Why do certain genes tend to be inherited together in a cell at the time of cell division? [HOTS]
Or
If the frequency of a parental form is higher than 25% in a dihybrid test cross, what does that indicate about the two genes involved? [HOTS]

Answer/Explanation

Answer:
Explaination: The genes show linkage and do not segregate independently of each other.

83. Morgan et al found that even on the same chromosome, recombination between some gene pairs was higher than that between some other gene pairs. Give reason for this observation.

Answer/Explanation

Answer:
Explaination: It is due to the distance between the gene pairs; more the distance, higher will be the recombination and vice versa.

84. If two genes are located far apart from each other, on a chromosome, how will the frequency of recombination get affected? [CBSE Sample Paper 2017,15]

Answer/Explanation

Answer:
Explaination:
– The two genes will segregate independently of each other and there will be 50% recombination.

85. Mention any two traits present on the X-chromosome of Drosophila.

Answer/Explanation

Answer:
Explaination: Eye colour, body colour, wing type. (any two)

86. Mention the contribution of genetic maps in human genome project. [AI 2011]

Answer/Explanation

Answer:
Explaination: The genetic maps were used as the starting point in the sequencing of whole genomes.

87. Do you think Mendel’s laws of inheritance would have been different if the characters he chose were located on the same chromosome? Why? [HOTS]

Answer/Explanation

Answer:
Explaination: Mendel could not have framed the law of independent assortment, if the genes for all the characters Mendel chose, were present on the same chromosome and showed the phenomenon of linkage.

88. Give an example of a polygenic trait in humans. [Delhi 2016C]

Answer/Explanation

Answer:
Explaination: Skin colour, intelligence, height, (any one)

89. Who suggested polygenic inheritance for the first time?

Answer/Explanation

Answer:
Explaination: Galton.

90. Give two examples of polygenic inheritances from plants.

Answer/Explanation

Answer:
Explaination:
(i) Cob length in maize.
(ii) Kernel colour in wheat.

91. Write the phenotypic ratio of the F2 progeny of a cross, involving polygenic trait controlled by three separate genes.

Answer/Explanation

Answer:
Explaination: 1 : 6 : 15 : 20 : 15 : 6 : 1.

92. On what basis is skin colour in humans considered polygenic? [AI 2015C]

Answer/Explanation

Answer:
Explaination: Skin colour in humans is controlled by three different genes and the phenotype is the cumulative effect of all the dominant alleles; hence, its inheritance is considered as polygenic.

93. Who first observed the X-chromosome? What was it called then?

Answer/Explanation

Answer:
Explaination: Henking first observed the X-chromosome. It was called X-body.

94. What are autosomes?

Answer/Explanation

Answer:
Explaination: All those chromosomes of an individual organism that are not involved in the determination of sex of that individual, are called autosomes.

95. Why is X-chromosome called sex chromosome?

Answer/Explanation

Answer:
Explaination: Since X-chromosome is involved in the determination of sex of an individual, it is called sex chromosome.

96. Give an example where
(a) males are XO and
(b) females are ZW.

Answer/Explanation

Answer:
Explaination:
(a) Grasshopper
(b) Fowls.

97. Theeggofan animal contains 10 chromosomes, of which one is X-chromosome. How many autosomes would there be, in the karyotype of this animal? [HOTS]

Answer/Explanation

Answer:
Explaination: 18 autosomes.

98. Give an example of an organism that exhibits haplodiploid sex determination system. [AI 2016C]

Answer/Explanation

Answer:
Explaination: Honeybee.

99. In a certain group of insects, some have 17 chromosomes and some have 18 chromosomes. Write about the gender of these two types of insects.

Answer/Explanation

Answer:
Explaination:
– Males have 17 chromosomes.
– Females have 18 chromosomes.

100. How many chromosomes do drones of honeybee possess? Name the type of cell division involved in the production of sperms by them. [AI 2015]

Answer/Explanation

Answer:
Explaination:
– Drones have 16 chromosomes.
– Mitosis occurs during production of sperms.

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Biology MCQs for Class 12 with Answers Chapter 6 Molecular Basis of Inheritance

July 17, 2020 by Kishen

Free PDF Download of CBSE Biology Multiple Choice Questions for Class 12 with Answers Chapter 6 Molecular Basis of Inheritance. Biology MCQs for Class 12 Chapter Wise with Answers PDF Download was Prepared Based on Latest Exam Pattern. Students can solve NCERT Class 12 Biology Molecular Basis of Inheritance MCQs Pdf with Answers to know their preparation level.

Molecular Basis of Inheritance Class 12 Biology MCQs Pdf

1. The DNA site where DNA-dependent RNA- polymerase binds for transcription, is called
(a) operator
(b) promotor
(c) regulator
(d) receptor

Answer

Answer: b

2. Operon model for regulation of transcription was proposed by
(а) Meselson and Stahl
(b) Jacob and Monod
(c) Watson and Crick
(d) Hershey and Chase

Answer

Answer: b

3. Eukaryotic RNA polymerase III catalyses the synthesis of
(a) mRNA
(b) rRNA
(c) hnRNA
(d) tRNA

Answer

Answer: d

4. The sequence of nitrogen bases in a # segment of a coding strand of DNA is ’ AATGCTTAGGCA. What will be the
sequence of nitrogen bases in the wRNA transcribed by it?
(a) UUA CGA AUC CGU
(b) AAU GCU AAC CGA
(c) AAU GCA AUC CGU
(d) AAU GCU UAG GCA

Answer

Answer: d

5. In the lac operon of E.coli, the i gene codes for
(a) inducer
(b) repressor
(c) lactase
(d) β-galactosidase

Answer

Answer: b

6. Which of the following sets of codons contains only termination codons?
(a) UAA, UGA, UAG
(b) UAA, UUU, UGG
(c) UAA, UAG, UAC
(d) UUU, UCC, UGG

Answer

Answer: a

7. The central dogma of molecular biology (genetic information flow) was modified by the discovery of
(a) RNA polymerase
(b) DNA ligase
(c) Reverse transcriptase
(d) DNA polymerase

Answer

Answer: c

8. The fact that a purine base always paired through hydrogen bonds with a pyrimidine base leads to, in the DNA double helix [NCERT Exemplar]
(a) the antiparallel nature
(b) the semiconservative nature
(c) uniform width throughout DNA
(d) uniform length in all DNA.

Answer

Answer: bc

9. The promoter site and the terminator site for transcription are located at [NCERT Exemplar]
(a) 3′ (downstream) end and 5′ (upstream) end, respectively of the transcription unit.
(b) 5′ (upstream) end and 3′ (downstream) end, respectively of the transcription unit.
(c) the 5′ (upstream) end.
(d) the 3′ (downstream) end.

Answer

Answer: b

10. The human chromosome with the highest and least number of genes in them are respectively [NCERT Exemplar]
(a) Chromosome 21 and Y
(b) Chromosome 1 and X
(c) Chromosome 1 and Y
(d) Chromosome X and Y

Answer

Answer: c

11. Discontinuous synthesis of DNA occurs in one strand, because [NCERT Exemplar]
(a) DNA molecule being synthesised is very long.
(b) DNA dependent DNA polymearse catalyses polymerisation only in one direction (5′ → 3′).
(c) it is a more efficient process.
(d) DNA ligase has to have a role.

Answer

Answer: b

12. Which of the following are the functions of RNA? [NCERT Exemplar]
(a) It is a carrier of genetic information from DNA to ribosomes synthesising polypeptides.
(b) It carries amino acids to ribosomes
(c) It is a constituent component of ribosomes
(d) All of the above.

Answer

Answer: d

13. In E.coli, the lac operon gets switched on when [NCERT Exemplar]
(a) lactose is present and it binds to the », repressor.
(b) repressor binds to operator.
(c) RNA polymerase binds to the operator.
(d) lactose is present and it binds to RNA polymerase.

Answer

Answer: a

14. The net electric charge on DNA and histone, is
(a) positive, negative
(b) negative, positive
(c) negative, negative
(d) positive, positive.

Answer

Answer: b

15. If the sequence of the nitrogen bases in the coding strand of DNA is 5’- ATGAATT-3’, the sequence of bases in the RNA transcribed by it will be ______ .

Answer/Explanation

Answer:
Explaination: 3’ AUGAAUU 5’

16. _____ step in transcription is catalysed by the enzyme DNA-dependent RNA polymerase.

Answer/Explanation

Answer:
Explaination: Elongation.

17. Lac operon shows the control of gene expression at the _____ level, in E.coli.

Answer/Explanation

Answer:
Explaination: Transcription.

18. The enzyme DNA polymerase catalyses the polymerisation of nucleotides in the ______ direction, for the lagging strand.

Answer/Explanation

Answer:
Explaination: 5′ → 3′

19. The last chromosome to be completely sequenced in the Human Genome Project (HGP) is ______ .

Answer/Explanation

Answer:
Explaination: Chromosome 1

20. RNA polymerase II in eukaryotes catalyses the transcription of ______ .

Answer/Explanation

Answer:
Explaination: hnRNA.

21. The presence of ______ group in every ribonucleotide makes RNA labile and reactive.

Answer/Explanation

Answer:
Explaination: 2′-OH.

22. Meselson and Stahl experimentally proved the _____ replication of DNA.

Answer/Explanation

Answer:
Explaination: Semiconservative.

23. During splicing in eukaryotes, the _____ are joined to from the RNA.

Answer/Explanation

Answer:
Explaination: Exons.

24. _____ factor functions as the initiation factor in the transcription of prokaryotes.

Answer/Explanation

Answer:
Explaination: Sigma (a)

25. Match the terms in Column I with those in Column II.

Column I	Column II
A. Transcription	1. A set of three bases on tRNA that is complementary to the bases of codon on mRNA.
B. Anticodon	2. A unit of DNA that codes for a polypeptide.
C. Cistron	3. Process of synthesis of polypeptide as dictated by mRNA.
D. Translation	4. Process by which mRNA carries the information from nucleus to ribosomes.

Answer/Explanation

Answer:
Explaination: A – 4, B – 1, C – 2, D – 3

26. Match the codons in Column I with the amino acids in Column II.

Column I	Column II
A. UUU	1. Termination
B. AUG	2. Tyrosine
C. UAA	3. Phenylalanine
D. AGU	4. Methionine
E. UAC	5. Serine

Answer/Explanation

Answer:
Explaination: A – 3, B – 4, C – 1, D – 5, E – 2

27. Polycistronic mRNA is generally found in eukaryotes. [True/False]

Answer/Explanation

Answer:
Explaination: False.

28. The process of translation of mRNA begins, when the mRNA encounters the large subunit of ribosome [True/False]

Answer/Explanation

Answer:
Explaination: False.

29. VNTR belongs to a class of satellite DNA, called micro-satellite. [True/False]

Answer/Explanation

Answer:
Explaination: False.

30. If a double-stranded DNA contains 20% cytosine, it will have 20% guanine in it. [True/False]

Answer/Explanation

Answer:
Explaination: True.

31. Termination/Stop codons do not have any tRNAs [True/False]

Answer/Explanation

Answer:
Explaination: True.

Directions (Q32 to Q35): Mark the odd one in each of the following groups.

32. UAA, UGG, UAG, UGA

Answer/Explanation

Answer:
Explaination: UGG

33. 5S rRNA, snRNA, hnRNA, tRNA

Answer/Explanation

Answer:
Explaination: hnRNA

34. Har Gobind Khorana, Marshal Nirenberg, Severo Ochoa, Alec Jeffreys.

Answer/Explanation

Answer:
Explaination: Alec Jeffreys.

35. Promoter, Inducer, Operator, Terminator.

Answer/Explanation

Answer:
Explaination: Inducer.

36. Name the two types of nucleic acids in living systems.

Answer/Explanation

Answer:
Explaination: Deoxyribonucleic acid and ribonucleic acid.

37. How is the length of DNA usually defined?

Answer/Explanation

Answer:
Explaination:
Length of DNA is defined as the:
(i) number of nucleotides in single-stranded DNA, and
(ii) number of pairs of nucleotides (base pairs) in double-stranded DNA.

38. Name the specific components and the linkage between them that form deoxyadenosine. [Delhi 2013C]

Answer/Explanation

Answer:
Explaination: The nitrogenous base, adenine is linked to deoxyribose sugar through N-glycosidic linkage.

39. Name the specific components and the linkages between them that form deoxy- guanosine. [All India 2013C]

Answer/Explanation

Answer:
Explaination: The nitrogenous base guanine is linked to deoxyribose sugar by N-glycosidic linkage.

40. In which position is the phosphate group linked to a nucleoside? Name the linkage too.

Answer/Explanation

Answer:
Explaination:
– A phosphate group is linked to the 5′-OH of a nucleoside.
– Phosphoester linkage.

41. Name the components ‘a’ and ‘b’ in the nucleotide with a purine, given below:

Answer/Explanation

Answer:
Explaination:
a – Phosphate group,
b – Nitrogenous base

42. Mention the carbon positions to which the nitrogenous base and the phosphate molecule are respectively linked in the nucleotide given below:

Answer/Explanation

Answer:
Explaination:
– Nitrogenous base at the first carbon.
– Phosphate at the fifth carbon.

43. Mention the position of the ribonucleotide, where the OH group is present.

Answer/Explanation

Answer:
Explaination: The OH-group is present at the 2′-position.

44. Who discovered the nucleic acid DNA? What was it called then?

Answer/Explanation

Answer:
Explaination:
Frederich Meischer discovered DNA.
It was called nuclein.

45. The two strands of DNA have antiparallel polarity. What does it mean?

Answer/Explanation

Answer:
Explaination:
It means that one of the strands of DNA has
5′ → 3′ polarity and the other strand has
3′ → 5′ polarity.

46. If the base adenine constitutes 30 per cent of an isolated DNA fragment, then what is the expected percentage of the base cytosine in it? [Delhi 2011C; HOTS]

Answer/Explanation

Answer:
Explaination: 20 per cent.

47. How does the flow of genetic information in HIV7 deviate from the ‘central dogma’ proposed by Francis crick? [Foreign 2013]

Answer/Explanation

Answer:
Explaination: HIV shows reverse transcription, i.e. formation of DNA on RNA template.

48. How does HIV differ from a bacteriophage? [Delhi 201OC]

Answer/Explanation

Answer:
Explaination: HIV has RNA as its genome and shows reverse transcription, while bacteriophage has double-stranded DNA as its genome and no reverse transcription.

49. How is the length of DNA usually calculated?

Answer/Explanation

Answer:
Explaination: The length of DNA is calculated by multiplying the total number of base pairs with the distance between two consecutive base pairs, which is 0.34 nm or 0.34 × 10^-9 m.

50. How may base pairs would a DNA segment of length 1.36 mm have? [Foreign 2017]

Answer/Explanation

Answer:
Explaination: It will have 1.36/0.34 × 10^-9bp, i.e., 4.6 × 10⁶bp.

51. What is a nucleoid?

Answer/Explanation

Answer:
Explaination: Nucleoid is the region in prokaryotic cells where DNA is organised as large loops held by some positively-charged proteins.

52. Name the positively charged protein around which the negatively charged DNA is wrapped. [AH India 2010C]

Answer/Explanation

Answer:
Explaination: Histone.

53. Name two basic amino acids that provide positive charge to histone proteins. [Delhi 2012C]

Answer/Explanation

Answer:
Explaination: Lysine and Arginine.

54. Write the role of histone proteins in packaging of DNA in eukaryotes. [Foreign 2017]

Answer/Explanation

Answer:
Explaination:
– Histone proteins are positively charged and are organized to from a unit of eight molecules, called a histone octamer,
– The negatively charged DNA molecule (of about 200 bp) wraps around the histone octamer to form a nucleosome, the repeating unit of chromatin.

55. Name the negatively charged and positively charged components of a nucleosome. [Delhi 2015C]

Answer/Explanation

Answer:
Explaination: Negatively charged component – DNA Positively charged component – histones.

56. Name the transcriptionally active region of chromatin in a nucleus. [Delhi 2015]

Answer/Explanation

Answer:
Explaination: Euchromatin.

57. Define transformation.

Answer/Explanation

Answer:
Explaination: Transformation is a phenomenon by which , the DNA isolated from one type of cell,
when introduced into another type, is able to bestow some of the properties of the former to the latter.

58. Write the conclusion Griffith arrived at, at the end of his experiments with Streptococcus pneumoniae. [All India 2017C]

Answer/Explanation

Answer:
Explaination:
– Griffith concluded that the R strain/non-virulent bacteria had been transformed y. into virulent form by the heat-killed S strain bacteria.
– It must be due to transfer of a transforming principle, i.e., genetic material from the heat-killed S strain bacteria.

59. What are bacteriophages?

Answer/Explanation

Answer:
Explaination: Bacteriophages are those viruses which infect the bacteria.

60. Why is RNA more reactive in comparison to DNA? [Delhi 2015CJ
Or
Why do RNA viruses undergo mutation and evolution faster than most of the DNA viruses? [HOTS]

Answer/Explanation

Answer:
Explaination: The 2′ OH-group in the nucleotides of RNA is a reactive group, that makes RNA labile 7- and easily degradable.

61. Write the scientific name of the plant on which Taylor et al performed their experiments.

Answer/Explanation

Answer:
Explaination: Vicia faba.

62. How long does the replication of human DNA take place?

Answer/Explanation

Answer:
Explaination: 38 minutes.

63. Name the enzyme and state its property that is responsible for continuous and discontinuous replication of the two strands of a DNA molecule. [Delhi 2013]

Answer/Explanation

Answer:
Explaination:
DNA-polymerase
– It polymerises the nucleotides only in 5′ → 3′ direction.

64. What is a replication fork?

Answer/Explanation

Answer:
Explaination: Replication fork is the Y-shaped structure formed when the double-stranded DNA is unwound up to a point during its replication.

65. Mention the direction in which:
(a) the leading strand is synthesised.
(b) discontinuous synthesis of DNA occurs.

Answer/Explanation

Answer:
Explaination:
(а) 5′ → 3′.
(b) 5′ → 3′.

66. Name the enzyme involved in the continuous replication of DNA strand. Mention the polarity of the template strand. [All India 2010]

Answer/Explanation

Answer:
Explaination:
DNA polymerase.
Template strand has 3′ → 5′ polarity.

67. Name the types of synthesis ‘a’ and ‘b’ occurring in the replication fork of DNA as shown below:

Answer/Explanation

Answer:
Explaination:
‘a’ – Continuous synthesis
‘b’ – Discontinuous synthesis.

68. Name the enzyme that joins the small fragments of DNA of a lagging strand during DNA replication. [Delhi 2013C]

Answer/Explanation

Answer:
Explaination: DNA – ligase.

69. Why are vectors needed for replication of DNA during rDNA technology? [HOTS]

Answer/Explanation

Answer:
Explaination: The vector provides the origin of replication.

70. What will happen if DNA replication is not followed by cell division in a eukaryotic cell? [All India 2014C]

Answer/Explanation

Answer:
Explaination: It will lead to polyploidy, a condition where the cell comes to possess more than two sets of chromosomes.

71. Define transcription.

Answer/Explanation

Answer:
Explaination: Transcription is the process of copying the genetic information from one of the strands of DNA into RNA.

72. Name the enzyme and the direction in which it catalyses the polymerisation of ribonucleotides.

Answer/Explanation

Answer:
Explaination:
– DNA-dependent RNA-polymerase.
– 5′ → 3′ direction.

73. Mention one difference to distinguish an exon from an intron. [Foreign 2016]

Answer/Explanation

Answer:
Explaination:
– An exon is a coding sequence that forms part of RNA.
– An intron is a non-coding sequence that is removed during splicing and does not forms a part of RNA.

74. When and at what end does the ‘tailing’ of hnRNA take place?

Answer/Explanation

Answer:
Explaination: Tailing occurs after splicing at the 3′ end.

75. At which ends do ‘capping’ and ‘tailing’ of hnRNA occur, respectively?

Answer/Explanation

Answer:
Explaination: Capping at the 5′ end and tailing at the 3′ end.

We hope the given Biology MCQs for Class 12 with Answers Chapter 6 Molecular Basis of Inheritance will help you. If you have any query regarding CBSE Class 12 Biology Molecular Basis of Inheritance MCQs Pdf, drop a comment below and we will get back to you at the earliest.

Biology MCQs for Class 12 with Answers Chapter 7 Evolution

July 17, 2020 by Kishen

Free PDF Download of CBSE Biology Multiple Choice Questions for Class 12 with Answers Chapter 7 Evolution. Biology MCQs for Class 12 Chapter Wise with Answers PDF Download was Prepared Based on Latest Exam Pattern. Students can solve NCERT Class 12 Biology Evolution MCQs Pdf with Answers to know their preparation level.

Evolution Class 12 Biology MCQs Pdf

1. Evolutionary convergence is characterised by
(а) development of characteristics by random mutations.
(b) development of similar characteristics in different groups of organisms of different ancestry.
(c) development of dissimilar characteristics in closely related groups of organisms.
(d) development of similar characteristics in related groups of organisms.

Answer

Answer: b

2. Homologous organs indicate
(a) convergent evolution.
(b) divergent evolution.
(c) adaptive radiation.
(d) natural selection.

Answer

Answer: b

3. Darwin judged the fitness of individuals by
(a) ability to defend itself.
(b) strategy to obtain food.
(c) number of offspring produced.
(d) dominance over other individuals.

Answer

Answer: c

4. Change of frequency of alleles in a population results in evolution. This statement is proposed in
(a) Darwin’s theory
(b) Lamarck’s theory
(c) Hardy-Weinberg principle
(d) de Vries theory.

Answer

Answer: c

5. Select the correct statement from the following options.
(a) Mutations are random and directional.
(b) Darwinian variations are small and direction less.
(c) Fitness is the end result of the ability to adapt and get selected by nature.
(d) All mammals have evolved vivipary as an adaptation.

Answer

Answer: c

6. Which type of selection is industrial melanism observed in moth, Biston bitularia [NCERT Exemplar]
(a) Stabilising
(b) Directional
(c) Disruptive
(d) Artificial

Answer

Answer: b

7. Analogous organs arise due to [NCERT Exemplar]
(a) divergent evolution
(b) artificial selection
(c) genetic drift
(d) convergent evolution

Answer

Answer: d

8. The bones of forelimbs of whale, bat, cheetah and man are similar in structure, because [NCERT Exemplar]
(a) one organism has given rise to another
(b) they share a common ancestor
(c) they perform the same function
(d) they have biochemical similarities.

Answer

Answer: b

9. Appearance of antibiotic-resistant bacteria is an example of [NCERT Exemplar]
(a) adaptive radiation
(b) transduction
(c) pre-existing variation in the population
(d) divergent evolution.

Answer

Answer: c

10. In 1953 S. L. Miller created primitive earth conditions in the laboratory and gave experimental evidence for origin of first form of life from preexisting non-living organic s molecules. The primitive earth conditions created include [NCERT Exemplar]
(a) low temperature, volcanic storms, atmosphere rich in oxygen
(b) low temperature, volcanic storms, reducing atmosphere
(c) high temperature, volcanic storms, non¬reducing atmosphere
(d) high temperature, volcanic storms, reducing atmosphere containing CH₄, NH₃ etc.

Answer

Answer: d

11, The most accepted line of descent in human evolution is [NCERT Exemplar]
(a) Australopithecus → Ramapithecus → Homo sapiens → Homo habilis
(b) Homo erectus → Homo habilis → Homo sapiens
(c) Ramapithecus → Homo habilis → Homo erectus → Homo sapiens
(d) Australopithecus → Ramapithecus → Homo erectus → Homo habilis → Homo sapiens.

Answer

Answer: c

12. A study of fossils in different sedimentary layers indicates the ______ period in which they existed.

Answer/Explanation

Answer:
Explaination: Geological.

13. ______evolution leads to homologous organs.

Answer/Explanation

Answer:
Explaination: Divergent.

14. Placental mammal lemur in Australia shows resemblance to the marsupial mammal, ______ .

Answer/Explanation

Answer:
Explaination: Spotted Cuscus.

15. Placental mammals and marsupial mammals of Australia show ______ evolution.

Answer/Explanation

Answer:
Explaination: Convergent.

16. De Vries believed that single step large mutation, called ______ caused speciation.

Answer/Explanation

Answer:
Explaination: Saltation.

17. ______ evolved into the first amphibians.

Answer/Explanation

Answer:
Explaination: Lobefins.

18. About 65 mya, ______ suddenly disappeared from the earth.

Answer/Explanation

Answer:
Explaination: Dinosaurs.

19. ______ probably lived in East African grasslands about 2 mya.

Answer/Explanation

Answer:
Explaination: Australopithecus.

20. The brain capacities of Homo habilis was about ______ cc.

Answer/Explanation

Answer:
Explaination: 650-800 cc

21. Fossils of ______ were discovered in Java.

Answer/Explanation

Answer:
Explaination: Homo erectus.

22. Match the items in Column I with those in Column II.

Column I	Column II
A. Ice-age (75000 – 10000 years before)	1. Neanderthal man.
B. 1.5 mya	2. Agriculture started.
C. Brain size of 1400 cc	3. Homo erectus; they probably ate meat.
D. 10000 years before	4. Modern Homo sapiens arose.
	5. Homo habilis; they probably did not eat meat.

Answer/Explanation

Answer:
Explaination: A – 4, B – 3, C – 1, D – 2

23. Match the organisms in Column I with the geological time scale of their appearance on the globe.

Column I	Column II
A. lawless fish	1. 500 mya
B. Dryopithecus	2. 320 mya
C. Sea weeds	3. 350 mya
D. Invertebrates	4. 200 mya – dominated the earth
E. Reptiles	5. 15 mya
	6. 1.5 mya

Answer/Explanation

Answer:
Explaination: A – 3, B – 5, C – 2, D – 1, E – 4

24. Prehistoric cave art developed after agriculture, about 18000 years ago. [True/False]

Answer/Explanation

Answer:
Explaination: False.

25. The skull of baby chimpanzee is more like the adult human skull than the skull of adult chimpanzee. [True/False]

Answer/Explanation

Answer:
Explaination: True.

26. It is believed that 3-4 mya, man-like primates walked in Eastern Africa.[True/False]

Answer/Explanation

Answer:
Explaination: True.

27. Due to continental drift, pouched mammals of Australia survived due to lack of competition. [True/False]

Answer/Explanation

Answer:
Explaination: True.

28. Tyrannosaurus was the smallest among the dinosaurs. [True/False]

Answer/Explanation

Answer:
Explaination: False.

Directions (Q29 to Q32): Mark the odd one in each of the following groups.
29. Carboniferous, Triassic, Devonian, Permian.

Answer/Explanation

Answer:
Explaination: Triassic.

30. Bobcat, Wolf, Ant eater, Spotted cuscus.

Answer/Explanation

Answer:
Explaination: Spotted cuscus.

31. Human hands, Wings of butterfly, Wings of bat, Wings of birds.

Answer/Explanation

Answer:
Explaination: Wings of butterfly.

32. Lamarckism, Darwinism, Branching descent, Natural selection.

Answer/Explanation

Answer:
Explaination: Lamarckism.

33. What is Evolutionary Biology?

Answer/Explanation

Answer:
Explaination: Evolutionary Biology is the study of history of life forms on earth.

34. When was the earth supposed to have been formed and when did life appear on the earth?

Answer/Explanation

Answer:
Explaination:
– Earth was supposed to have been formed ’ 4.5 billion years before.
– Life appeared about four billion years ago.

35. What was the idea of early Greek thinkers about origin of life?
Or
What is Theory of Panspermia?

Answer/Explanation

Answer:
Explaination: According to this theory (of early Greek philosophers) it was believed that units called ‘Spores’ or ‘pansperms’ came on the earth along with meteorites and they must have evolved into the various life forms.

36. Name the scientist who disproved spontaneous generation theory. [Delhi 2010]

Answer/Explanation

Answer:
Explaination: Louis Pasteur disproved the spontaneous generation theory.

37. State the two principal outcomes of the experiments conducted by Louis Pasteur on origin of life. [Delhi 2019]
Or
What did Louis Pasteur’s experiment on ‘Killed yeast’ demonstrate? Name the theory that got disproved on the basis of his experiment. [Foreign 2013]

Answer/Explanation

Answer:
Explaination:
– It demonstrated that life comes only from pre-existing life.
– Theory of spontaneous generation was disproved.

38. What role does an individual organism play as per Darwin’s theory of natural selection? [Delhi 2017]

Answer/Explanation

Answer:
Explaination: The individual organism passes on the (genetic) variations) to the next generation; the useful variations are selected by nature and it can lead to speciation.

39. How did Charles Darwin express ‘fitness’? [Delhi 2019]
Or
What is ‘fitness’ of an individual according to Darwin? [Delhi 2017]

Answer/Explanation

Answer:
Explaination: The fitness, according to Darwin, refers ultimately to reproductive fitness.

40. Name the scientist who also came to similar conclusion as Darwin. Where did he work?

Answer/Explanation

Answer:
Explaination: Alfred Wallace. He worked in Malay Archepelago.

41. What are fossils?

Answer/Explanation

Answer:
Explaination: Fossils are the remnants and/or impressions of the life-forms that lived in the remote past.

42. Define biogeography.

Answer/Explanation

Answer:
Explaination: Biogeography refers to the study of distribution of living organisms in different parts of the earth.

43. Name any two vertebrate body parts that are homologous to human forelimbs.

Answer/Explanation

Answer:
Explaination: Wings of birds, flippers of whales, forelimbs of dog/cat, wings of bats. (any two)

44. Identify the examples of convergent evolution from the following: [Delhi 2013]
(a) Flippers of penguins and dolphins.
(b) Eyes of Octopus and mammals.
(c) Vertebrate brains.

Answer/Explanation

Answer:
Explaination: (a) and (b)

45. Identify the examples of homologous structures from the following: [Delhi 2013]
(a) Vertebrate hearts.
(b) Thoms in Bougainvillea and tendrils of Cucurbita.
(c) Food storage organs in sweet potato and potato.

Answer/Explanation

Answer:
Explaination: (a) and (b)

46. Name the type of evolution that has resultedin the development of structures like wings of butterfly and bird. What are such structures called? [Delhi 2014 C]

Answer/Explanation

Answer:
Explaination:
– Convergent evolution.
– They are called analogous organs/ structures.

47. ‘Sweet potato tubers and potato tubers are the result of convergent evolution’. Justify the statement. [Delhi 2013]

Answer/Explanation

Answer:
Explaination: Sweet potato tubers and potato tubers are analogous structures, evolved for the same function; analogous structures result from convergent evolution.

48. Write the similarity between the wing of a butterfly and the wing of a bat. What do you infer from the above with reference to evolution? [Delhi 2012; HOTS]
Or
Comment on the similarity between the wing of a cockroach and the wing of a bird. What do you infer from the above with reference to evolution? [AI 2012; HOTS]
Or
Comment on the similarity between the flippers of dolphins and penguins, with reference to evolution. [Foreign 2012]

Answer/Explanation

Answer:
Explaination:
– They are analogous organs, which perform similar functions, but are dissimilar in their anatomy and origin.
– Analogous organs are the result of convergent evolution.

49. State the significance of biochemical similarities amongst diverse organisms in evolution. [Delhi 2012]

Answer/Explanation

Answer:
Explaination: The biochemical similarities point to the same shared ancestry among diverse organisms.

50. State a reason for the increased population of dark-coloured moths coinciding with the loss of lichens (on tree barks) during industrialisation period in England. [Foreign 2015]

Answer/Explanation

Answer:
Explaination:
– During the post-industrialisation period, the tree trunks became dark due to deposition of industrial smoke and soot.
– The dark-coloured moths were able to camouflage better and were not picked up by the predators and hence, increased their population size.

51. Why are lichens regarded as pollution indicators?

Answer/Explanation

Answer:
Explaination: Since, they do not grow in areas that are polluted, lichens are regarded as pollution indicators.

52. Name two animals that have evolved along with Tasmanian wolf in the Australian continent.

Answer/Explanation

Answer:
Explaination: Sugar glider/Bandicoot/Koala/Numbat/ Wombat/Kangaroo/Marsupial rat/ Marsupial mole.

53. What is the basis of origin of variations in organisms as described by Hugo de Vries? [AI 2013C]

Answer/Explanation

Answer:
Explaination: Mutation.

54. List the two characteristics of mutation that help in explaining evolution. [Delhi 2011C]

Answer/Explanation

Answer:
Explaination:
Mutations are:
(i) random, and
(ii) directionless.

55. According to de-Vries, what is saltation? [Delhi 2016]
Or
What is saltation according to De-Vries? [Delhi 2014C]

Answer/Explanation

Answer:
Explaination: Saltation refers to single-step large mutation that results in speciation.

56. What does Hardy-Weinberg equation p² + 2pq + q² = 1, convey? [Foreign 2011]

Answer/Explanation

Answer:
Explaination: It indicates genetic equilibrium, i.e. the allele frequencies in a population are stable and remain constant from generation to generation.

57. What is evolution according to Hardy- Weinberg? [CBSE Sample Paper 2013, 2014]

Answer/Explanation

Answer:
Explaination: Disturbance in genetic equilibrium, i.e. change of frequency of alleles in a population, would be considered as evolutionary change.

58. How does a population become ‘founders’ of a new species? [AI 2012C]
Or
When does a species become founders to cause founder effect? [Foreign 2010]

Answer/Explanation

Answer:
Explaination: When the change in allele frequency is so different that the new sample of population becomes a different species, the original drifted population becomes founders to cause founder effect.

59. According to Hardy-Weinberg principle, the allele frequency of a population remains constant. How do you interpret the change of frequency of alleles in a population?

Answer/Explanation

Answer:
Explaination: The change in frequency of alleles indicates evolutionary change.

60. Pick out the ancestral line of Angiosperms from the list: Conifers, Seed ferns, Cycads, Ferns.

Answer/Explanation

Answer:
Explaination: Seed ferns.

61. Coelacanth was caught in South Africa. State the significance of discovery of Coelacanth in the evolutionary history of vertebrates. [Guwahati 2019]
Or
State the significance of Coelacanth in evolution. [AI 2012]

Answer/Explanation

Answer:
Explaination:
– Coelacanth has evolved into the first amphibians; they are fish with stout and strong fins that could move on land and go back to water.
– They were thought to be extinct.

62. What technical term is given to the fish-like reptiles?

Answer/Explanation

Answer:
Explaination: Ichthyosaurs.

63. Write the names of the following:
(a) A 15 mya primate that was ape-like.
(b) A 2 mya primate that lived in East African grasslands. [CBSE 2018]

Answer/Explanation

Answer:
Explaination:
(a) Dryopithecus
(b) Australopithecus

64. Name the common ancestor of great apes and man. [AI 2011]

Answer/Explanation

Answer:
Explaination: Dryopithecus

65.

Biology MCQs for Class 12 with Answers Chapter 7 Evolution

Study the ladder of human evolution given above and answer the following questions: [Delhi 2010C]
(a) Where did Australopithecines evolve?
(b) Write the scientific name of Java man.

Answer/Explanation

Answer:
Explaination:
(a) Australopithecines evolved in East African Grasslands.
(b) Homo erectus.

We hope the given Biology MCQs for Class 12 with Answers Chapter 7 Evolution will help you. If you have any query regarding CBSE Class 12 Biology Evolution MCQs Pdf, drop a comment below and we will get back to you at the earliest.

Biology MCQs for Class 12 with Answers Chapter 8 Human Health and Disease

July 17, 2020 by Kishen

Free PDF Download of CBSE Biology Multiple Choice Questions for Class 12 with Answers Chapter 8 Human Health and Disease. Biology MCQs for Class 12 Chapter Wise with Answers PDF Download was Prepared Based on Latest Exam Pattern. Students can solve NCERT Class 12 Biology Human Health and Disease MCQs Pdf with Answers to know their preparation level.

Human Health and Disease Class 12 Biology MCQs Pdf

1. In the immune system, interferons are a part of
(a) physiological barriers
(b) cellular barriers
(c) physical barriers
(d) cytokine barriers.

Answer

Answer: d

2. The letter T in T-lymphocytes refers to
(a) tonsil
(b) thalamus
(c) thymus
(d) thyroid

Answer

Answer: c

3. Use of anti-histamines and steroids gives a quick relief from
(a) allergy
(b) nausea
(c) cough
(d) fever

Answer

Answer: a

4. The immunoglobulin abundant in colostrum, is
(a) Ig D
(b) Ig A
(c) Ig G
(d) Ig M

Answer

Answer: b

5. Diacetyl morphine is commonly known as
(a) cocaine
(b) hashish
(c) ganja
(d) heroin

Answer

Answer: d

6. Opium is extracted from
(a) Atropa belladona
(b) Papaver somniferum
(c) Erythroxylum coca
(d) Cannabis sativa

Answer

Answer: b

7. The disease chikungunya is transmitted by
[NCERT Exemplar]
(a) houseflies
(b) Aedes mosquitoes
(c) cockroach
(d) female Anopheles

Answer

Answer: b

8. Anti venom against snake poison contains [NCERT Exemplar]
(a) antigens
(b) antigen-antibody complexes
(c) antibodies
(d) enzymes

Answer

Answer: c

9. Which of the following glands is large sized at birth but reducies in size with aging? [NCERT Exemplar]
(a) Pineal
(b) Pituitary
(c) Thymus
(d) Thyroid

Answer

Answer: c

10. The substance produced by a cell on viral infection that can protect other cells from further infection is [NCERT Exemplar]
(a) serotonin
(b) colostrum
(c) interferon
(d) histamine

Answer

Answer: c

11. Many diseases can be diagnosed by observing the symptoms in the patient. Which group of symptoms are indicative of pneumonia? [NCERT Exemplar]
(a) Difficulty in respiration, fever, chills, cough, headache
(b) Constipation, abdominal pain, cramps, blood clots
(c) Nasal congestion and discharge, cough, sorethroat, headache
(d) High fever, weakness, stomach pain, loss of appetite and constipation

Answer

Answer: a

12. Transplantation of tissues/organs to save certain patients often fails due to rejection of such tissues/organs by the patient. Which type of immune response is responsible for such rejections? [NCERT Exemplar]
(a) auto-immune response
(b) humoral immune response
(c) physiological immune response
(d) cell-mediated immune response

Answer

Answer: d

13. ______ mosquitoes are the vectors of dengue and chikungunya.

Answer/Explanation

Answer:
Explaination: Aedes.

14. ______ barriers protect the non-infected cells from further viral infections.

Answer/Explanation

Answer:
Explaination: Cytokine.

15. Cell-mediated immunity is provided by ______ .

Answer/Explanation

Answer:
Explaination: T-cells.

16. Among non-infectious diseases, ______ is the major cause of death.

Answer/Explanation

Answer:
Explaination: Cancer.

17. ______ test is performed to confirm typhoid.

Answer/Explanation

Answer:
Explaination: Widal.

18. Plasmodium enters the human body as ______ .

Answer/Explanation

Answer:
Explaination: Sporozoite.

19. ______ is the toxin released by the rupture of RBCs into the blood in a malaria- infected person.

Answer/Explanation

Answer:
Explaination: Hemocoin.

20. _____ is the filarial worm.

Answer/Explanation

Answer:
Explaination: Wuchereria.

21. ______ are the physical, chemical and biological agents that cause cancer.

Answer/Explanation

Answer:
Explaination: Carcinogens.

22. Heroin is obtained by _______ of morphine.

Answer/Explanation

Answer:
Explaination: Acetylation.

23. Match the organisms (Pathogens) in Column I with the diseases they cause in Column II.

Column I	Column II
A. Rhino vims	1. Ringworm
B. Plasmodium	2. Filariasis
C. Salmonella	3. Common cold
D. Trichophyton	4. Typhoid
E. Wuchereria	5. Malaria
	6. Amoebiasis

Answer/Explanation

Answer:
Explaination: A – 3, B – 5, C – 4, D-1, E – 2

24. Match the items in Column I with those in Column II.

Column I	Column II
A. Physiological barrier	1. Interferons
B. Cytokine barrier	2. Skin of the body
C. Cellular barrier	3. Tear in the eyes
D. Physical barrier	4. Antibodies in colostrum
	5. Polymorpho-nuclear leucocyte

Answer/Explanation

Answer:
Explaination: A – 3, B – 1, C – 5, D – 2

25. Humoral immunity is responsible for rejection of organ transplants. [True/False]

Answer/Explanation

Answer:
Explaination: False

26. a-interferon activates the immune system and help to destroy the tumour cells. [True/False]

Answer/Explanation

Answer:
Explaination: True

27. Cannabinoids affect the digestive system. [True/False]

Answer/Explanation

Answer:
Explaination: False

28. Nicotine, the alkaloid in tobacco causes the hallucinogenic effect. [True/False]

Answer/Explanation

Answer:
Explaination: False

29. Colostrum contains antibody IgA and provides passive immunity. [True/False]

Answer/Explanation

Answer:
Explaination: True

Directions (Q30 to Q33): Mark the odd one in each of the following groups.

30. Saliva in the mouth, Mucus coating in respiratory tract, Tear in the eyes, Acid in the stomach.

Answer/Explanation

Answer:
Explaination: Mucus coating in respiratory tract

31. Thymus, spleen, appendix, tonsil.

Answer/Explanation

Answer:
Explaination: Thymus

32. Charas, Heroin, Marijuana, Hashish.

Answer/Explanation

Answer:
Explaination: Heroin

33. Typhoid, Pneumonia, Diphtheria, Malaria.

Answer/Explanation

Answer:
Explaination: Malaria

34. Who discovered blood circulation in humans?

Answer/Explanation

Answer:
Explaination: William Harvey discovered blood circulation in humans.

35. Name one infectious and one non-infectious disease that is the major cause of mortality.

Answer/Explanation

Answer:
Explaination:
– Infectious disease – AIDS.
– Non-infectious disease – Cancer.

36. High fever, loss of appetite, stomach pain and constipation are some of the symptoms seen in a patient. How would the doctor confirm that the patient is suffering from typhoid and not amoebiasis?

Answer/Explanation

Answer:
Explaination: It would be confirmed by Widal test.

37. Name one respiratory disease that infects the lung alveoli and one that does not infect the lungs.

Answer/Explanation

Answer:
Explaination:
– Pneumonia infects lung alveoli.
– Common cold does not infect the lungs.

38. Name two diseases that spread by droplet infection.

Answer/Explanation

Answer:
Explaination: Common cold and pneumonia.

39. Name two diseases whose spread can be controlled by the eradication of Aedes mosquitoes. [CBSE 2918]
Or
Name two viral diseases transmitted by Aedes mosquito.

Answer/Explanation

Answer:
Explaination: Dengue and chikungunya.

40. Name the stage of Plasmodium that gains entry into the human, when bitten by an infected female Anopheles. [Delhi 2017C]

Answer/Explanation

Answer:
Explaination: Sporozoite is the stage.

41. Trace the route of Sporozoite at Plasmodium, when it enters the human body through the bite of female Anopheles, till its entry into RBCs. [Delhi 2017C]

Answer/Explanation

Answer:
Explaination: Into human blood → Liver cells → blood → RBCs.

42. Name the host where fertilisation occurs in the life cycle of Plasmodium [Delhi 2017C]

Answer/Explanation

Answer:
Explaination: Anopheles mosquito.

43. How does malaria differ from chikungunya with reference to their vectors? [All India 2010C]

Answer/Explanation

Answer:
Explaination:
– Anopheles mosquito is the vector of malaria.
– Aedes mosquito is the vector of chikungunya.

44. Malaria, typhoid, pneumonia and amoebiasis are some of the human infectious diseases. Which ones of these are transmitted through mechanical carriers? [Foreign 2011]

Answer/Explanation

Answer:
Explaination: Amoebiasis, typhoid.

45. How does haemozoin affect the human body, when released in blood during malarial infection? [Foreign 2014]

Answer/Explanation

Answer:
Explaination: Haemozoin causes the chill and high fever recurring at periodic intervals (of 3-4 days).

46. Why is Gamhusia introduced into drains and ponds? [AH India 2014]

Answer/Explanation

Answer:
Explaination: Gambusia feeds on the mosquito larvae and thereby helps in eliminating the mosquito vectors of the diseases like Malaria, Chikungunya, dengue, etc.

47. What causes swelling of the lower limbs in patients suffering from filariasis?

Answer/Explanation

Answer:
Explaination: The filarial worms live for many years in the lymphatic vessels of lower limbs and cause inflammation and swelling there.

48. What role do macrophages play in providing immunity to humans?

Answer/Explanation

Answer:
Explaination: Macrophages phagocytose and destroy the microbes (pathogens) and provide protection from diseases.

49. How do monocytes act as a cellular barrier in humans to provide innate immunity? [CBSE 2018 C]
Or
In what way is monocyte a cellular barrier w’ith reference to immunity? [Delhi 2015 C]

Answer/Explanation

Answer:
Explaination: Monocytes are phagocytic and destroy the pathogenic microbes.

50. How do neutrophils act as a cellular barrier to pathogens in humans?

Answer/Explanation

Answer:
Explaination: Neutrophils phagocytose and destroy the microbes (pathogens).

51. How do cytokine barriers provide innate immunity in humans? [CBSE 2018]
Or
How do cytokine barriers help in evading viral infections? [Delhi 2015 C]
Or
How do interferons protect us? [AH India 2012]

Answer/Explanation

Answer:
Explaination: Cytokine barriers, i.e. interferons are produced by the body cells in response to viral infection and protect the other non- infected cells from viral infection.

52. Name any two secretions in the body that act as ‘physiological barriers’ of innate immunity.

Answer/Explanation

Answer:
Explaination: Saliva in the mouth, acid in thestomach and tears from eyes. (any two)

53. Name the kind of barrier of innate immunity, where some cells secrete interferons when infected. [All India 2012]

Answer/Explanation

Answer:
Explaination: Cytokine barrier.

54. When does a human body elicit an anamnestic response? [AH India 2013]

Answer/Explanation

Answer:
Explaination: When a human body encounters a pathogen for the second time, it elicits an anamnestic response.

55. Why does a human being elicit an anamnestic response? [Delhi 2011C]

Answer/Explanation

Answer:
Explaination: Ahuman body elicits an anamnestic response Because our immune system appears to have memory of the first encounter with the same pathogen.

56. Suggest a method to ensure anamnestic response in humans. [Delhi 2017]

Answer/Explanation

Answer:
Explaination: Giving a booster dose of the vaccine can induce an anamnestic response.

57. Why is secondary immune response more intense than the primary immune response in humans? [All India 2014]

Answer/Explanation

Answer:
Explaination: Because body appears to have memory of the first encounter (in the form of memory B cells and memory T cells).

58. Why is the antibody-mediated immunity called humoral immunity? [HOTS]

Answer/Explanation

Answer:
Explaination: Antibodies are the glycoproteins that keep circulating in the body fluids (humors); hence, it is called humoral immunity.

59. Thymus of a new-born child was degenerating right from birth due to a genetic disorder. Predict its two impacts on the health of the child. [CBSE Sample Paper 2016]

Answer/Explanation

Answer:
Explaination:
– The number of T-lymphocytes will decrease and hence, the immune system will become weak.
– The child will become prone to any infection, which normally could be overcome.

60. Give two examples of passive immunity.

Answer/Explanation

Answer:
Explaination:
(i) The immunity provided by colostrum to the new-born.
(ii) The immunity provided to the foetus by the antibodies that pass through placenta from the mother.
(iii) Immunity provided against rabies and tetanus through inoculation.

61. Which category of adaptive immunity is provided by vaccination? Why? [HOTS]

Answer/Explanation

Answer:
Explaination: Active Immunity. It is called so because the antibodies are developed by the vaccinated person’s own cells in response to the antigens.

62. What is it that prevents a child to suffer from a disease he/she is vaccinated against? Give one reason. [Delhi 2010; HOTS]

Answer/Explanation

Answer:
Explaination:
– His body develops antibodies that circulate in the body fluids and neutralise the pathogenic agent during subsequent encounters.
– Memory B cells and memory T cells are retained in the system.

63. State the function of mast cells in allergy response. [Foreign 2013]

Answer/Explanation

Answer:
Explaination: Mast cells release chemicals like serotonin and hlitaminc, which cause allergy.

64. Why do pollen grains of some flowers trigger ‘sneezing’ in some people? [Foreign 2012]

Answer/Explanation

Answer:
Explaination: Pollen grains are allergens and cause allergic reactions in some people by causing release of histamine and serotonin from the mast cells.

65. Name the condition in vertebrates, where the body attacks self-cells. [All India 2017C]

Answer/Explanation

Answer:
Explaination: Autoimmunity.

66. Name the category of disease in which ’ ‘Rheumatoid arthritis’ in human, put under. [All India 2017 C]
Or
Name the category of the disease, rheumatoid arthritis. [Foreign 2012]

Answer/Explanation

Answer:
Explaination: Autoimmune disease.

67. What is an autoimmune disease? [All India 2017C]

Answer/Explanation

Answer:
Explaination: An autoimmune disease is the one caused when the immune system of the body goes off the track and attacks ‘self’ cells.

68. What would happen to the immune system, if thymus gland is removed from the body of a person?

Answer/Explanation

Answer:
Explaination:
– Thymus is a primary lymphoid organ.
– If that is removed, T-lymphocytes cannot differentiate and their number decreases; so the immune system becomes weak and the person is prone to any infection.

69. Where are mucosal associated lymphoid tissues present in the human body and why?

Answer/Explanation

Answer:
Explaination: Mucosal associated lymphoid tissues are present within the lining of the respiratory, digestive and urinogenital tracts; they con-stitute about 50 per cent of the lymphoid tissue.

70. Name the two types of cells in which HIV multiplies, after gaining entry into the human body.

Answer/Explanation

Answer:
Explaination: Macrophages and Helper T-lymphocytes.

71. Retroviruses have no DNA. However, the DNA of the infected host cell does possess viral DNA. How is it possible? [All India 2015; HOTS]

Answer/Explanation

Answer:
Explaination: Retroviruses carry out reverse transcription (formation of DNA on RNA template) as they possess the enzyme, reverse transcrip-tase; the DNA is integrated with host DNA.

72. Why is sharing of injection needles between two individuals not recommended? [Delhi 2013]

Answer/Explanation

Answer:
Explaination: It is to prevent the spread of HIV or hepatitis B through contaminated needles.

73. Why does an AIDS patient suffer from many other infections? [HOTS]

Answer/Explanation

Answer:
Explaination: Due to reduction in the number of helper T-cells, the immune system of the person is weak and he suffers from infections that otherwise could have been overcome.

74. What are protooncogenes?

Answer/Explanation

Answer:
Explaination: Protooncogenes are the genes in normal cells, which when activated under certain conditions, could lead to oncogenic trans-formation of the cells.

75. Indiscriminate diagnostic practices using X-rays, etc. should be avoided. Give one reason. [Delhi 2015]

Answer/Explanation

Answer:
Explaination: X-rays are ionising radiations and can prove to be carcinogenic, i.e. cancer-causing.

76. Mention the useful as well as the harmful drug obtained from the latex of poppy plant. [Foreign 2012]

Answer/Explanation

Answer:
Explaination: Morphine.

77. Write the chemical structure of morphine.

Answer/Explanation

Answer:
Explaination:
Biology MCQs for Class 12 with Answers Chapter 8 Human Health and Disease 1

78. What is heroin chemically?

Answer/Explanation

Answer:
Explaination: Diacetylmorphine.

79. What is meant by drug abuse?

Answer/Explanation

Answer:
Explaination: When drugs are taken for a purpose other than their normal clinical use and in amounts/concentrations or frequency that impair one’s physical, physiological and psychological functions, it constitutes drug abuse.

80. Write the structural formula of a cannabinoid molecule.

Answer/Explanation

Answer:
Explaination:
Biology MCQs for Class 12 with Answers Chapter 8 Human Health and Disease 2

81. (a) Where are cannabinoid receptors present in a human body?
(b) Name the body system affected by cannabinoids.

Answer/Explanation

Answer:
Explaination:
(a) Cannabinoid receptors are present in the brain.
(b) They affect the cardiovascular system.

82. Name two plants other than coca plant that have hallucinogenic properties.

Answer/Explanation

Answer:
Explaination: Atropa belladona and Datura.

83. How does smoking tobacco in human lead to oxygen deficiency in their body? [Delhi 2012]

Answer/Explanation

Answer:
Explaination: Smoking increases the carbon monoxide content of the blood, which reduces the concentration of haem bound oxygen; hence there is oxygen deficiency in their body.

84. Define adolescence.

Answer/Explanation

Answer:
Explaination: Adolescence refers to the period and process of rapid growth and physical and mental development (attitudes and beliefs) from childhood to adulthood.

85. Why do the doses of drugs keep on increasing or lead to greater intake and addiction? [HOTS]

Answer/Explanation

Answer:
Explaination: It is because the tolerance level of the receptors in our body increases; they start responding to higher doses only and hence there is greater intake.

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