Principles of Inheritance and Variation MCQ | Class 12 | Biology | Chapter-5

Principles of Inheritance and Variation MCQ Chapter 5

Below are some of the very important NCERT Principles of Inheritence and Variation MCQ Class 12 Biology Chapter 5 with Answers. These Principles of Inheritence and Variation MCQ have been prepared by expert teachers and subject experts based on the latest syllabus and pattern of term 1 and term 2. We have given these Principles of Inheritence and Variation MCQ Class 12 Biology Questions with Answers to help students understand the concept.

MCQ Questions for Class 12 Biology Chapter 5 are very important for the latest CBSE term 1 and term 2 pattern. These MCQs are very important for students who want to score high in CBSE Board.

We have put together these NCERT Questions Principles of Inheritence and Variation MCQ for Class 12 Biology Chapter 5 with Answers for the practice on a regular basis to score high in exams. Refer to these MCQs Questions with answers here along with a detailed explanation.

MCQ 1-48

1. Genetics is the branch of Biology which deals with Inheritance of characters from parents to progeny, called as …A… and the degree by which progeny differs from the parents, called …B…

(a) A – variation, B – heredity
(b) A – resemblance, B – inheritance
(c) A – heredity, B – difference
(d) A – heredity, B – variation

2. Experimental material in Mendel’s experiment was

(a) Pisum sativum
(b) Orzya sativa
(c) Mirabilis jalapa
(d) Lathyrus odorotus

3. Which one of those given below is the period for Mendel’s hybridization experiments?

(a) 1856-1863
(b) 1840-1850
(c) 1857-1869
(d) 1870-1877

4. The number of contrasting characters studied by Mendel for his experiment was

(a) 14
(b) 4
(c) 2
(d) 7

5. Among the following characters, which one was not considered by Mendel in his experiment on pea?

(a) Stem – Tall or Dwarf
(b) Trochomes – Glandular or Non-glandular
(c) Seed – Green or Yellow
(d) Pod – Inflated or Constricted

6. What contributed to Mendel’s success?

(I) Selection of pureline pea varieties
(II) knowledge of history
(III) selecting one character at a time
(IV) statistical analysis and mathematical logic

Choose the correct option.

(a) I, II, III and IV
(b) II and III
(c) I, III and IV
(d) II, III and IV

7. Choose the incorrect match.

(a) Phenotype – physical appearance of an organism
(b) Genotype – expressed genes
(c) Homozygous – identical alleles of a gene present at the time locus
(d) Heterozygous – genes of an elderly pair are not same

8. The character which appears in F1-generation is called

(a) recessive
(b) dominant
(c) latent
(d) none of these

9. 3:1 ratio in F2-generation is explained by

(a) law of partial dominance
(b) law of dominance
(c) law of incomplete dominance
(d) law of purity of gametes

10. Graphical representation using with probability of all possible genotypes of an offspring is genetic cross can be calculated is called

(a) Burnett square
(b) Morgan square
(c) Unit square
(d) Test cross

11. Test cross is used to

(a) check heterozygous in F1-generation
(b) check heterozygous in F2-generation
(c) check independant assortment
(d) check segregation

12. A cross between two tall plants resulted in offspring having few dwarf plants. What would be the genotype of both the parents?

(a) TT & Tt
(b) Tt & Tt
(c) TT & TT
(d) Tt & tt

13. Match the following.

COLUMN 1	COLUMN 2
(A) Monohybrid cross	(I) T and t
(B) Test cross	(II) TT
(C) Alleles	(III) TT x Tt
(D) Homozygous tall	(IV) Tt x tt

(a) (A) – 3, (B) – 1, (C) – 4, (D) – 2
(b) (A) – 4, (B) – 3, (C) – 2, (D) -1
(c) (A) – 3, (B) – 4, (C) – 1, (D) – 2
(d) (A) – 3, (B) – 1, (C) – 4, (D) – 2

14. The law of segregation of characters is also called the law of purity of gametes because can’t be contaminated.

(a) True
(b) False
(c) Can’t say
(d) Partly true or false

15. F2-generation in a Menderian cross showed that both genotypic and phenotypic ratios are same as 1:2:1. It represents a case of

(a) codominance
(b) dihybrid cross
(c) monohybrid cross with complete dominance
(d) monohybrid Cross with incomplete dominance

16. Incomplete dominance is shown by

(a) Primrose
(b) Mirabilis
(c) Helianthus
(d) China rose

17. During the study of incomplete dominance, in a cross between true breeding red flowers (RR) and true breeding white flowers (rr), when F1 was self pollinated, the resulted F2 ratio may be

(a) 1(RR)red : 2(Rr)pink : 1(rr)white
(b) 2(RR)red : 1(Rr)pink : 1(rr)white
(c) 1(RR)red : 1(Rr)pink : 2(rr)white
(d) 3(RR)red : 1(rr)white

18. In Antirrhinum, to plants with pink flowers were hybridised. The F1 plant produced red, pink and white flowers in proportion of one red, two pink and one white. What could be the genotype of the two plants used for hybridization? Red flower colour is determined by RR and white by rr genes.

(a) rrrr
(b) RR
(c) Rr
(d) rr

19. Which Mendelian idea is depicted by a cross in which F1-generation resembles both the parents?

(a) incomplete dominance
(b) law of dominance
(c) Inheritance of one gene
(d) codominance

20. Which of the following characteristic represent ‘Inheritance of blood groups’ in human?

(I) Dominance
(II) Codominance
(III) Multiple alleles
(IV) Incomplete dominance
(V) Polygenic inheritance

(a) I, IV and V
(b) I, II and III
(c) II, III and IV
(d) I, III and V

21. Starch synthesis gene in pea plant in heterozygous condition produces starch grain of intermediate size. This shows

(a) complete dominance
(b) incomplete dominance
(c) codominance
(d) none of the above

22. When there are more than two alleles controlling the same character. They are called

(a) pleitrophy
(b) polyalleles
(c) multiple alleles
(d) none of these

23. The type of gametes formed by the genotype are 

(a) RY, Ry, rY, ry
(b) RY, Ry, ry, ry
(c) Ry, Ry, ry, ry
(d) Rr, RR, Yy, YY

24. Independent assortment means

(a) separation of characters of one parent
(b) non separation of characters of one parent
(c) combination of parental characters
(d) separation of parental characters

25. When a pure tall plant (TT) having rounded seeds (RR) are crossed with dwarf plant (tt) having wrinkle seed (rr) and their F1 progeny are crossed among themselves to produce F2-generation. How many phenotypes will be observed?

(a) 16
(b) 9
(c) 4
(d) 2

26. Chromosomal theory of inheritance was proposed by

(a) Sutton and Boveri
(b) Bateson and Punnett
(c) TH Morgan
(d) Watson and Crick

27. The chromosomes as well as genes occur in pair and the two alleles of a gene pair are located on

(a) homologous chromozomes
(b) non-homologous chromosomes
(c) single chromosome
(d) all of the above

28. Morgan’s experimental organism was

(a) Drosophila melanogaster
(b) Mangifera indica
(c) Mirabilis jalapa
(d) Drosophila indica

29. The term …A… describes the physical association of genes on chromosome and the term …B… describes the generation of non parental gene combination.

(a) A – association, B – recombination
(b) A – linkage, B – recombination
(c) A – recombination, B – linkage
(d) A – association, B – dissociation

30. Which of the following will not result in variation among siblings?

(a) independent assortment of genes
(b) crossing over
(c) linkage
(d) mutation

31. Linkage was discovered by

(a) Miller
(b) Morgan
(c) de Vries
(d) Mendel

32. All genes located on the same chromosome?

(a) form different groups depending upon their relative distance
(b) form one linkage group
(c) will not form any linkage group
(d) form interactive groups that affect the phenotype

33. Select the correct statement from the ones given below with respect to dihybrid cross.

(a) tightly linked genes on the same chromosome show higher recombination
(b) genes far apart on the same chromosome show very few recombination
(c) genes loosely linked on the same chromosome show similar recombination as the tightly linked ones
(d) tightly linked genes on the same chromosome show very few recombinations

34. Which of the following is suitable for experiment on linkage?

(a) aaBB x aaBB
(b) AABB x aabb
(c) AaBb x AaBb
(d) AAbb x AaBB

35. Genes A, B and C are linked. Genes A and B are more close than A and C.

(I) A might be before B and C
(II) B might be between A and C
(III) C might be between A and B
(IV) More crosses cannot occur between A and C then A and B

Find out the correct option.

(a) I & II
(b) II & III
(c) III & IV
(d) I, II & IV

36.  Mendel conducted a number of crosses and studied but could never discovered linkage. What could be the reason for this?

(I) some genes are linked but they are too far apart for crossing over to be distinguished from independent assortment
(II) linked genes were never tested for the same time in same cross
(III) the seven genes were present on the seven chromosomes
(IV) the jeans underwent mutation during subsequent crossing

Choose the correct option.

(a) I & II
(b) II & III
(c) III & IV
(d) only IV

37. Distance between the genes and percentage of recombination shows

(a) a direct relationship
(b) an inverse relationship
(c) a parallel relationship
(d) no relationship

38. In polygenic inheritence

(a) many genes govern a single character
(b) heterozygous organisms express only one allele
(c) heterozygous organisms express both alleles
(d) a single gene influences many characters

39. Allergenic gene show

(a) similar genotype
(b) different karyotype
(c) different phenotype
(d) none of the above

40. Which one of the following pairs of feature is a good example of polytechnic inheritance?

(a) human height and skin colour
(b) ABO blood group in humans and flower colour of Mirabilis jalapa
(c) Hair pigment of mouse and tongue rolling in humans
(d) human eye colour and Sickle Cell anaemia

41. In human skin colour inheritance, the genotype with three dominant and three recessive alleles will produce

(a) darkest skin colour
(b) lightest skin colour
(c) intermediate skin colour
(d) patches of black and white

42. Occasionally a single gene may express more than one affect. The phenomenon is called

(a) multiple allelism
(b) mosaicism
(c) pleitropy
(d) polygeny

43. A pleitropic gene

(a) controls a trait only in combination with another gene
(b) controls multiple sheets in an individual
(c) is expressed only in primitive plants
(d) is a gene involved evolved during pliocene

44. The best example of pleitropy is

(a) skin colour
(b) phenylketonuria
(c) colour blindness
(d) ABO blood group

45. Match the following.

COLUMN 1	COLUMN 2
(A) Dominance	1. Many genes govern a single character
(B) Codominance	2. In a heterozygous organism, only one allele expresses itself
(C) Pleiotropy	3. In a heterozygous organism, both alleles express themselves fully
(D) Polygenic inheritance	4. A single gene influences many characters

(a) (A) – 2, (B) – 1, (C) – 4, (D) – 3
(b) (A) – 2, (B) – 3, (C) – 4, (D) – 1
(c) (A) – 4, (B) – 1, (C) – 2, (D) – 3
(d) (A) – 2, (B) – 3, (C) – 1, (D) – 2

46. Sex determination is controlled by …A… and the remaining chromosomes which are not involve in sex determination are …B… .

(a) A – allosomes, B – autosomes
(b) A – allosomes, B – sex-chromosomes
(c) A – sex-chromosomes, B – allosomes
(d) A – autosomes, B – sex-chromosomes

47. In XX and XY type of sex determination

(a) males are heterogametic
(b) females are isogametic
(c) both (a) and (b)
(d) none of the above options are correct

48. Heterogamety is the term where an individual produces two types of gametes. The most appropriate answer is

(a) male Drosophilia fly
(b) female Drosophilia fly
(c) female bird
(D) both (a) and (c)

49. In XO type of sex determination

(a) females produce two different types of gametes
(b) males produce two different types of gametes
(c) females produce gamete with Y-chromosome
(d) males produce single type of gamete

50. The condition in which females lack one sex chromosome whereas males are homogametic, the sex chromosomal representation is

(a) Z0-ZZ
(b) XY-XX
(c) XX-X0
(d) ZW-ZZ

MCQ Answers

1. (d)

2. (a)

Gregor Johann Mendel conducted hybridization experiments on garden pea (Pisum satinum) and proposed the laws of inheritance in living organisms.

3. (a)

Mendel conducted hybridization experiments on pea plants for 7 years between 1856 and 1863 and his data was published in 1865.

4. (a)

Mendel selected 7 pages or 14 characters of true breeding pea plant varieties for his experiment.

5. (b)

Trichomes are the epidermal tissue structure. These are formed when epidermal cells become granular and hair like, called as trichomes. This character was not amongst the seven pairs of characters of the pea plant.

6. (c)

7. (b)

The genetic composition of an organism, with respect to one or more characters whether the gene is expressed or not is called genotype.

8. (b)

The characters that appear on the F1-generation are called dominant traits and those that appeared on the first time in the F2-generation are called recessive traits.

9. (b)

10. (c)

Punnett square was developed by British Geneticist Reginald C. Punnett. It is a graphical representation to calculate the probability of all possible genotypes of offsprings in genetic cross.

11. (a)

Crossing of F1-individual having dominant phenotype with its homozygous recessive parent is called test cross and the progeny of test cross is called test cross progeny. Test cross was devised by Mendel to prove that F1 obtained by crossing 2 pure breeding parents is heterozygous or hybrid.

If the unknown genotype is homozygous, half the progeny will exhibit the dominant trait and other half exhibit the recessive trait. So, a test cross is used to check heterozygosity in F1 generation.

12. (b)

If a cross between 2 tall plants resulted in a few dwarf offspring, then the parental genotypes are Tt and Tt.

It can be explained by the following example.

The F1 plants of genotype, Tt are self-pollinated.

Phenotypic ratio Tall : Dwarf if 3:1

Genotypic ratio Pure tall : Hybrid tall : Pure dwarf is 1:2:1

13. (c)

14. (a)

The law of segregation of characters are also called the law of purity of gametes because gametes have only one of the two alleles for each character.

15. (d)

Monohybrid cross with incomplete dominance show the same genotype and phenotype ratio, i.e. 1:2:1, as depicted by the cross given below

Genotypic ratio 1(AA) : 2 (Aa) : 1(aa)

Phenotypic ratio 1(Red) : 2(Pink) : 1(White)

16. (b)

Carl Correns reported incomplete dominance in Antirrhinum majus and Mirabilis jalapa. In both the cases there are two types of flower colours in pure state, red and white. When the two types of plants are crossed, the hybrid of plants of F1 -generation of pink flowers.

The pink colour apparently appears due to mixing of red and white colours incomplete dominance.

17. (a)

18. (c)

19. (d)

In codominance both alleles of a pair express themselves fully in F1 generation, so it resembles both the parents.

20. (b)

Dominance, codominance and multiple alleles are the characteristic that represent ‘inheritance of blood group’ in humans. ABO blood groups are determined by the gene. There are multiple (3) alleles, IA, IB and i of this gene. Alleles IA and IB are dominant over i. However, when IA and IB alleles are present together. they show codominance.

21. (b)

In starch synthesis gene, following conditions to seen.

BB – rounded (due to more starch synthesis)
bb – wrinkled (due to less starch synthesis)
Bb – in between round off rounded off wrinkled size. It produces starch of intermediate quantity between BB to bb homozygois condition. So it is incomplete dominance.

22. (c)

23. (a)

Number of gametes calculated is 2ⁿ, where n = number of heterozygotes.

RrYy is a dihybrid, so four types of gametes are formed (2²) as RY, Ry, rY, ry.

24. (a)

According to law of independent assortment, the two factors of each character resort or separate independent of the factors of other characters at the same time gamut formation. They get randomly re-arranged in the offspring, producing both parental and new combination of traits.

25. (c)

Four type of phenotypes will be observed. They are tall round, tall wrinkled, dwarf round and dwarf wrinkled.

26. (a)

The chromosomal theory of inheritance proposed by Sutton and Boveri. It states that chromosomes are the vehicle of genetic heredity. Neither Mendelian genetics nor gene linkage it is perfectly accurate, instead, chromosome behaviour involves segregation, independent assortment and occasionally linkage.

27. (a)

28. (a)

29. (a)

30. (c)

Linkage will not result in variation among siblings. Morgan carried out several dihybrid crosses in Drosophila to study genes that were sex-linked.

Morgan came to know that genes were located on the X chromosome and also observed that when the two genes in a dihybrid cross was situated on the same chromosome, the proportion of parental gene combination were much higher than the non parental type. It indicates that due to the physical association of the two genes there will be no variation among siblings.

31. (b)

The hypothesis that linked genes tend to remain in their original combination because of the location in the same chromosome was given by TH Morgan in 1991.

32. (b)

All the genes, present on a particular chromosome form a linkage group. The number of linkage groups of the species corresponds to the total number of different chromosomes of that species.

33. (d)

When two genes are close together on the same chromosome, they do not assort independently and are said to be linked tightly. The shoulders frequency of recombination. Whereas gene located on different chromosomes assort independently and have recombination frequency of 50%.

34. (b)

AABB x aabb if suitable for experiment on linkage. Linkage is the tendency for certain genes to be inherited together, because they are on the same chromosome. Thus, parental combinations of characters are found more frequently in offsprings than non-parental characters.

35. (a)

Since, genes A and B are more close and genes A and C, therefore gene A has to be present before genes B and C with gene B present in between genes A and C.

Other options are incorrect and can be corrected as

• Gene C is not between genes A and B
• More crosses have occurred between A and C than A and B

36. (a)

Mendel could not find out linkage because all of this experiment characters of pea were not linked. They were present far apart from each other on four different chromosomes.

37. (a)

The distance between the genes and percentage of recombination shows a direct relationship. This can be explained as when genes are close together or a link exhibit low recombination frequencies and when they are far apart the recombination is high.

38. (a)

39. (c)

Polygenic trait is governed by more than one gene express a part why a dominant allele of each gene express a part of trait and full trait is expressed by dominant alleles of all genes. Depending upon geneotype, it produces multiple or different phenotypes.

40. (a)

Human height and skin colour are good examples of polygenic inheritance .

41. (c)

42. (c)

43. (b)

The ability of a gene to have multiple phenotypic effects because it influences on number of character simultaneously is known as pleiotropy.

The gene having a multiple phenotypic effect because of its ability to control expression of two or more characters is called pleiotropic gene. In human beings, pleitropy is exhibited by syndromes like Sickle Cell anaemia and phenylketonuria.

44. (b)

The best example of fluid therapy is phenylketonuria.

In phenylketonuria, a single gene mutation that codes for enzyme phenylalenine hydroxylase is seen.

This manifest itself through phenotypic expression characterized by mental retardation, reduction in hair and skin pigmentation.

45. (b)

46. (a)

47. (a)

In XX-XY types of sex determination males are heterogametic, therefore produce two types of sperms with X and Y. But females are homogametic, therefore, produces only single type of ovum with X.

48. (d)

49. (b)

50. (a)

Assertion-Reason Based MCQ

Code

1. Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of the Assertion (A).
2. Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
3. Assertion (A) is true, but Reason (R) is false.
4. Assertion (A) is false, but Reason (R) is true.

1. Assertion Offspring have characteristic of both the parents

Reason Characters pass from the parents to the progeny

2. Assertion A pair of contrasting characters is termed as allele

Reason Two alleles of a gene express equality in an individual

3. Assertion True breeding lines have stable trait in inheritance for several generations

Reason Mendel conducted cross pollination experiments on true breeding line

4. Assertion In F2 generation the traits seen in the progeny were identical to that parents

Reason The progeny of the F2 generation shows no blending of traits

5. Assertion Genes are not passed on from one generation to the next

Reason Genes serve as the units of inheritance

6. Assertion Gametes receive only one allele of gene

Reason Mitosis occurs during gamete formation leading to the formation of haploid gametes.

7. Assertion Starch synthesis in pea seeds is controlled by one gene.

Reason This gene has two alleles (B & b)

8. Assertion A women can go to the court if a man refuses to own his child. He has blood group B and women has A while the child has O

Reason Genetically, she is right, he can be the father of the child

9. Assertion The linked genes tend to get inherited together

Reason The link between them fails to break

10. Assertion Insects show female heterogamety.

Reason In insects, males have XO sex chromosomes and female have XX sex chromosome.

Assertion-Reason Based MCQ Answers

1. (1)

Offsprings bear characteristics of both the parents. These characters pass from the parents via their gametes into their progeny. This is called inheritance.

2. (3)

Some genes have just a few alleles, but others have many. A dominant allele is one that is expressed to a greater than the other alleles.

3. (2)

True breeding lines show inheritance of pure characters from several generations. This is because true breeding lines are homozygous for the traits. Therefore, Mendel conducted cross-pollination experiments, between different true breeding lines to study the concept of inheritance.

4. (1)

There was no blending of characters in the progeny of F2-generation. As a result, the offspring exhibited traits which were exactly identical to their parents.

5. (4)

Genes are passed on from one generation to the next and thus called as the units of inheritance.

6. (3)

Meiosis occurs during the process of gamete formation which leads to the formation of haploid gametes.

7. (2)

8. (1)

Man has blood group B, it means he will have alleles I^BI^B or I^BI^O and women has blood group A, that can have alleles I^AI^A or I^AI^O. So there is a possibility of producing a child with blood group O. In such condition, both the women and man are heterozygous and have blood group genotype I^BI^O and I^AI^O, respectively.

9. (1)

When two genes are close together on the same chromosome, they don’t assort independently and are said to be linked. The linked gene tends to get inherited together as the link between them fails to break.

10. (1)

The non-allelic genes for red hair and prickles are inherited together as these are located in close association on the same chromosomes.

Case-Study Based Questions

1. Read the following passage and answer the following questions accordingly.

Mendel is known as the ‘Father of Genetics’ because of his groundbreaking work on inheritance in pea plants 150 years ago. At the age of 21, Mendel while working in a monastery in Brunn (now when Czech Republic) began a series of experiments in the botanical garden.

He found out how traits are passed from one generation to other, therefore inheritance. He studied these in peace (Pisum sativum) because they are easy to grow and can be shown each year.

(i) During the experiments, Mendel called genes by the term

(a) traits
(b) characters
(c) factors
(d) qualities

(ii) Under which topic, Mendel’s work was published in ‘Natural History Society of Brunn’?

(a) Mendel’s law of Inheritance
(b) Experiments in Plant Hybridization
(c) Experiment on Heredity and Variation
(d) Origin of Species

(iii) Mendel was lucky to work on pea plant for his experiment because

(a) pea flowers are normally self-pollinated, but can be readily cross pollinated
(b) there are several varieties in peace with observable alternative form of a trait
(c) the selected 7 characters in the experiment are located on the same chromosome
(d) the selected 7 characters were located on different chromosomes

(iv) Which is correct about trade tools and by Mendel for his experiments on pea plant?

(a) Terminal pod was dominant
(b) Constricted pod was dominant
(c) Green coloured pod was dominant
(d) All plants recessive

2. Read the following passage and answer accordingly.

In court, a woman of AB blood group claims that man of O blood group is father of her son having O blood group. The judge orders to take the help of a geneticist to solve the problem. Finally it was concluded that men of O blood group was not the father of women’s son.

(i) Which is the following phenomenon is seen in blood group inheritance in human?

(a) Pleitropy
(b) polytechnic inheritance
(c) codominance
(d) epistasis

(ii) A person with blood group A can show genotype

(a) I^AI^A
(b) I^AI^B
(c) I^BI^A
(d) I^BI^B

(iii) ABO blood group system is seen in human which is controlled by

(a) B-gene
(b) C-gene
(c) I-gene
(d) n-gene

(iv) Out of the three alleles of gene I, the sugar polymers on the plasma membrane of RBCs is controlled by how many alleles?

(a) all 3
(b) 2
(c) 1
(d) 0

3. Read the following passage and answer accordingly.

Genes are segments of Dioxyribonucleic acid (DNA) that contain the code for a specific protein that functions in one or more types of cell in the body.

Chromosomes are structures within cells that contain a person’s genes. Genes are passed down the generation in a particular manner and we receive roughly half of a genetic material from each parent. Chromozones described and determine gender and any change in them causes chromosomal abnormalities.

(i) The concept of chromosome movement during meiosis to explain Mendel’s law was used by

(a) Sutton and Boveri
(b) Malthus
(c) Correns
(d) Morgan

(ii) Crossing over in diploid organism is responsible for

(a) segregation of alleles
(b) recombination in linked alleles
(c) dominance of genes
(d) linkage between genes

(iii) If the genes are located in a chromosome as

A-B-C-D-E-O-T.

Which of the gene pairs will have the least probability of being not inherited together?

(a) C & D
(b) A & T
(c) A & B
(d) O & T

(iv) Both chromosome and gene (Mendelian factors) whether dominant or recessive are transmitted from one generation to the next generation in

(a) changed form
(b) an alternate form
(c) an altered formed
(d) disintegrated form

4. Read the following passage and answer accordingly.

Colour blindness is a sex-linked recessive disorder which results in defect in either red or green cornea of eye. It does not mean not seeing any colour at all. In fact it leads to the failure of discrimination between red and green colour.

The gene for colour blindness is present in X chromosome which is present mostly in male because of the presence of only one X chromosome as compared to the chromosomes in female. Heterozygous female has normal vision but a carrier can pass on the disorder to some of her sons.

(i) A woman has X-linked condition on one of her X-chromosomes. This chromosome can be inherited by

(a) only grandchildren
(b) only sons
(c) only daughter
(d) son and daughter

(ii) Anish is having colour blindness and married to Sheela who is not colorblind. What is the chance that their son will have the disease?

(a) 100%
(b) 50%
(c) 25%
(d) 0%

(iii) If both parents of a male child are normal, what is the chances of child being colorblind?

(a) it is impossible
(b) it is possible only if father’s mother was colorblind
(c) it is possible only if mother’s father was colorblind
(d) it is possible even when all the four grandparents had normal vision

(iv)  If a colorblind man marries a woman who is carrier of colorblindness the probability of the sun being colorblind is

(a) 50%
(b) 0.5
(c) 0.75
(d) 1

Case-Study Based MCQ Answers

1. (i)(c) (ii)(b) (iii)(d) (iv)(c)
2. (i)(c) (ii)(a) (iii)(c) (iv)(b)
3. (i)(a) (ii)(b) (iii)(b) (iv)(b)
4. (i)(d) (ii)(d)

Final Words

From the above article, you have practiced Principles of Inheritance and Variation MCQ of Class 12 Biology Chapter 5. We hope that the above-mentioned MCQs for term 1 of chapter 5 Principles of Inheritance and Variation MCQ would will surely help you in your exam. 

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