PYQ NEET MCQ Chapter 5: Principles of Inheritance and Variation

Hello NEET aspirants, worried about the previous year Biology NEET questions? Don’t worry, we got you covered! Here are 15 most important NEET MCQs from Chapter 5- Principles of Inheritance and Variation of Class XII.

ATTEMPT ALL QUESTIONS BY YOURSELF FIRST THEN CHECK THE SOLUTIONS. BRIEF EXPLANATIONS ABOUT THE SOLUTIONS ARE GIVEN AT THE END AS WELL.

Table of Contents

Previous year Biology NEET questions

Questions from 2019

In Antirrhinum (Snapdragon), a red flower was crossed with a white flower and in F, generation all pink flowers were obtained. When pink flowers were selfed, the F₂ generation showed white, red and pink flowers. Choose the incorrect statements from the following. (2019)

(a) The Law of segregation does not apply in this experiment.

(b) This experiment does not follow the Principle of Dominance.

(d) Ratio of F₂ is 1/4(red):2/4(pink):1/4 (white).

Select the incorrect statement. (2019)

(a) Human males have one of their sex-chromosome much shorter than others.

(b) Male fruit flies are heterogametic.

(d) In domesticated fowls, the sex of progeny depends on the type of sperm rather than the egg.

What map unit (centiMorgan) is adopted in the construction of genetic maps? (2019)

(a) A unit of distance between genes on chromosomes, representing 50% crossover.

(b) A unit of distance between two expressed genes, representing 10% crossover.

(d) A unit of distance between genes on chromosomes, representing 1% crossover.

The frequency of recombination between genes present on the same chromosome as a measure of the distance between genes was explained by:-(2019)

(a) Sutton Boveri

(b) T.H. Morgan

(d) Alfred Sturtevant.

What is the genetic disorder in which an individual has an overall masculine development, gynecomastia, and is sterile? (2019)

(a) Down’s syndrome

(b) Turner’s syndrome

(d) Edward syndrome

Which of the following characteristics ‘inheritance of blood groups’ in humans? (2019)

(i) Dominance

(ii) Codominance

(iii) Multiple alleles

(iv) Incomplete dominance

(v) Polygenic inheritance

(a) (ii), (iii) and (v)

(b) (i), (ii) and (iii)

(d) (i), (iii) and (v)

Questions from 2018

Which of the following pairs is wrongly matched? (2018)

(a) Starch synthesis in pea: Multiple alleles

(b) ABO blood grouping: Codominance

(d) T.H. Morgan: Linkage

A woman has an X-linked condition on one of the X chromosomes. This chromosome can be inherited by:- (2018)

(a) only daughters

(b) only sons

(d) both sons and daughters.

Thalassemia and sickle cell anaemia are caused due to a problem in globin molecule synthesis. Select the correct statement. (2017)

(a) Both are due to a quantitative defect in globin synthesis.

(b) Thalassemia is due to less synthesis of molecules.

(d) Both are due to a qualitative defect synthesis.

Questions from 2017

The genotypes of a husband and wife are AB and Ai. Among the blood types of their children, how many different genotypes and phenotypes are possible? (2017)

(a) 3 genotypes; 4 phenotypes

(b) 4 genotypes; 3 phenotypes

(d) 3 genotypes; 3 phenotypes

A disease caused by an autosomal primary nondisjunction is:- (2017)

(a) Klinefelter’s syndrome

(b) Turner’s syndrome

(d) Down’s syndrome.

Among the following characters, which one was not considered by Mendel in his experiments on pea? (2017)

a)Trichomes-Glandular or non-glandular

(b) Seed-Green or yellow

(d) Stem-Tall or dwarf

Which one from those given below is the period for Mendel’s hybridisation experiments? (2017)

(a) 1840-1850

(b) 1857-1869

(d) 1856-1863

Questions from 2016

The mechanism that causes a gene to move from one linkage group to another is called:- (2016)

(a) inversion

(b) duplication

(d) crossing-over.

If a colour-blind man marries a woman who is homozygous for normal colour vision, the probability of their son being colour-blind is:- (2016)

(a) 0

(b) 0.5

(d) 1.

Well done buddy! A guide to previous year Biology NEET questions is incomplete without solutions and explanations, let’s find out!

Solutions of previous year Biology NEET questions

Short Explanation of Solutions (1-10)

The Law of Segregation is universal and is applied everywhere. Snapdragon is a common example of incomplete dominance and hence all other options are correct.
The Y chromosome in human males is shorter, male fruit flies are indeed heterogametic because they show male heterogamety, grasshoppers have XO type of sex determination hence all three first options are correct. In fowls, female heterogamety is there and sex is dependent on the egg and not the sperm hence option D is the correct answer.
In Gene Mapping a unit distance on chromosome = 1% crossing over frequency. Eg: 10 unit distance between two genes indicates 10% crossing over frequency.
Alfred Sturtevant was a Student of T.H.Morgan and made the conclusion that frequency of recombination = distance between the genes on the chromosome when he was researching linkage.
Klinefelter’s syndrome occurs due to nondisjunction of sex chromosome resulting in XXY type of sex chromosome. In this condition, overall masculinity develops, however, there is the presence of gynecomastia and sterility.
The correct option is B because: in blood groups, dominance is there, e.g- IAi shows A Blood group. Codominance is observed in AB Blood Group IAIB and since three alleles govern the character of the blood group in an individual multiple allelism can be observed too.
Starch Synthesis in Pea is a classical case of Codominance and no multiple allelism is observed in Starch Synthesis in Plants.
In Sex determination, in homo sapiens, the mother has a XX chromosome and the father has an XY chromosome. The daughter inherits the X chromosome of the father and either X chromosome of the mother. Similarly, the son inherits the Y chromosome of the father and the X chromosome of the mother. Hence if a mother has X linked condition on either X chromosome it can be inherited by either son/daughter.
Thalassemia is a quantitative disorder whereas sickle cell anaemia is a qualitative problem. Hence option B is correct.
From the AB Blood group, IA and IB alleles can segregate and from the A Blood group with genotype IAi alleles IA and i can be segregated. Hence blood groups i.e. A, B, AB are possible. O Blood group is not possible, hence 3 genotypes are there. Phenotypes are 4 = IAIA IBIA IAi IBi.

Short answers (11-15)

11. Causal reason for Down’s syndrome is autosomal primary nondisjunction of chromosome number 21.

12. Trichomes as a character in the pea experiment were not considered by Mendel, the rest of all characters were considered.

13. Mendel performed his pea experiments from 1856-1863.

14. Translocation is the mechanism that allows the movement of genes from one linkage group to another. In translocation, as the name indicates ‘location change,’ the gene breaks off and attaches to another chromosome hence forming a new linkage group.

15. Since the mother has normal vision, her genotype for colour blindness is XX homozygous. The father is colour blind and hence has genotype XcY. The son inherits the X chromosome from his mother and the Y chromosome from his father. Since the son will not inherit the X chromosome from the father his probability of being colour blind is 0.

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