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NEET Exam  >  NEET Test  >  Biology Class 12  >  Assertion & Reason Test: Principles of Inheritance & Variation - 1 - NEET MCQ

Principles of Inheritance & Variation - 1 - Free Assertion Reason Questions


MCQ Practice Test & Solutions: Assertion & Reason Test: Principles of Inheritance & Variation - 1 (15 Questions)

You can prepare effectively for NEET Biology Class 12 with this dedicated MCQ Practice Test (available with solutions) on the important topic of "Assertion & Reason Test: Principles of Inheritance & Variation - 1". These 15 questions have been designed by the experts with the latest curriculum of NEET 2026, to help you master the concept.

Test Highlights:

  • - Format: Multiple Choice Questions (MCQ)
  • - Duration: 30 minutes
  • - Number of Questions: 15

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Assertion & Reason Test: Principles of Inheritance & Variation - 1 - Question 1
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Direction: In the following questions a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as :

Assertion (A) : The chances of having a child with Down’s syndrome increases if the age of the mother is between 20 to 25.

Reason (R) : The chances of having a child with Downs syndrome increases with the age of the mother because age adversely affects meiotic chromosome behaviour.

Detailed Solution: Question 1

Down’s syndrome increases if the age of the mother exceeds forty years because age adversely affects meiotic chromosome behaviour. Meiosis in the egg cells is not completed, until after fertilization. During this long gap (till meiosis is not completed) egg cells are arrested in prophase I and chromosomes are unpaired. The greater the time they remain unpaired greater the chance for unpairing and chromosome non-disjunction.

Assertion & Reason Test: Principles of Inheritance & Variation - 1 - Question 2
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Direction: In the following questions a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as :

Assertion : Number of chromosomes in one genome is equal to number of linkage groups.

Reason : Two homologous chromosomes form a linkage group.

Detailed Solution: Question 2

 The assertion that the number of chromosomes in one genome is equal to the number of linkage groups is generally correct, as each chromosome typically represents one linkage group. However, the reason provided — "Two homologous chromosomes form a linkage group" — is incorrect. A linkage group is formed by genes located on a single chromosome, not two homologous chromosomes. Thus, the correct answer should be option 3: "Assertion (A) is true but reason (R) is false."

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Assertion & Reason Test: Principles of Inheritance & Variation - 1 - Question 3
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Direction: In the following questions a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as :

Assertion (A) : Haemophilia is an autosomal disorder.

Reason (R) : A haemophilic father can never pass the gene for haemophilia to his son.

Detailed Solution: Question 3

Haemophilia is a sex-linked recessive disorder in which X-chromosome has the haemophilic gene. A haemophilic father can never pass the gene for haemophilia to his son.

Assertion & Reason Test: Principles of Inheritance & Variation - 1 - Question 4
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Direction: In the following questions a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as :

Assertion : In some Drosophila, bilateral gynandromorphs are found.

Reason : Ihe gynandromorphs are formed by an irregularity in mitosis at the first cleavage of the zygote.

Detailed Solution: Question 4

Abnormal chromosomal behaviour in insects can result in the formation of gynandromorphs or sexual mosaics in which some parts of the animal are female and other parts are male. Some gynandromorphs in Drosophila are bilateral intersex. Bilateral gynandromorphs have been explained on the basis of an irregularity in mitosis at the first cleavage of the zygote. Infrequently a chromosome lags in division and does not arrive at the pole in time to be included in the reconstructed nucleus. When one of the X chromosomes of an XX (female) zygote lags in the spindle, one daughter nucleus receives two X chromosomes. A mosaic body pattern is thus established. One nucleus in. the nuclei stage would be XX (female) and one would be XO (male).

on the same chromosome while unlinked genes are the ones found on different chromosomes. Linked gene show dihybrid ratio of 3 :1. Linked genes do not show independent assortment.

Assertion & Reason Test: Principles of Inheritance & Variation - 1 - Question 5
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Direction: In the following questions a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as :

Assertion (A) : The frequency of red-green colour blindness is many times higher in females than that in males.

Reason (R) : In females if only one X-chromosome of female possess allele for colour blind character she becomes the colour blind.

Detailed Solution: Question 5

Colour blindness is X-linked sex inheritance. The frequency of red-green colour blindness is many times higher in males than that in the females because males have only one X chromosomes therefore they develop colour blindness when their sole X- chromosome has the allele for it. Thus, males are more prone to colour blindness while females are carriers. For becoming colour blind, the female must have the allele for it in both her X-chromosomes and if only one X-chromosome of female possess allele for colour blind character she becomes the carrier for this characteristic.

Assertion & Reason Test: Principles of Inheritance & Variation - 1 - Question 6
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Direction: In the following questions a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as :

Assertion : Y chromosome causes maleness.

Reason: If the number of X chromosome is more than one, femaleness dominates.

Detailed Solution: Question 6

In mammals, the presence of a Y chromosome is required for the development of a male sex phenotype. In contrast, the Y chromosome plays no significant role in sex determination in Drosophila. A Y chromosome is required for maleness, moreover, the presence of a single Y chromosome is sufficient even in the presence of several X chromosomes (e.g XXXXY).

Assertion & Reason Test: Principles of Inheritance & Variation - 1 - Question 7
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Direction: In the following questions a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as :

Assertion (A) : Sickle cell anaemia is an example of point mutation.

Reason (R) : It is caused by addition or deletion of nitrogenous bases in the DNA or mRNA.

Detailed Solution: Question 7

Sickle-cell anaemia is caused by a single point mutation in the beta haemoglobin gene which converts a GAG, codon into GUG, which code for valine amino acid rather than glutamic acid.

Assertion & Reason Test: Principles of Inheritance & Variation - 1 - Question 8
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Direction: In the following questions a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as :

Assertion : Karyotypes study is used to detect of chromosomal aberrations.

Reason: Karyotypes can be used to know the sex of unborn child.

Detailed Solution: Question 8

Karyotype is the chromosome complement of a cell, individual or group of similar individuals that provides description of number, types and other characteristics of chromosomes. Any change in the chromosome number is detected immediately. Chromosomal aberrations or abnormalities are found about. This chromosome technique has made it possible to know the sex of developing fetus by drawing amniotic fluid and preparing karyotypes from cells derived from fetus floating in this fluid.

Assertion & Reason Test: Principles of Inheritance & Variation - 1 - Question 9
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Direction: In the following questions a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as :

Assertion (A) : Crossing of F1 hybrid with the recessive parent is known as test cross.

Reason (R) : Test cross helps to determine the unknown genotype by crossing it with the recessive parent.

Detailed Solution: Question 9

Crossing F1 with recessive parent will. may inherit recessive genotypic characters as dominant characters in their offspring.

Assertion & Reason Test: Principles of Inheritance & Variation - 1 - Question 10
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Direction: In the following questions a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as :

Assertion (A) : Crossing of F1 hybrid with the recessive parent is known as test cross.

Reason (R) : Test cross helps to determine the unknown genotype by crossing it with the recessive parent.

Detailed Solution: Question 10

Haplodiploidy is a type of sex determination in which the male is haploid while the female is diploid. It occur in some insects like bees, ants and wasps. Male insects are haploid because they develop parthenogenetically from unfertilised eggs. Meiosis

Assertion & Reason Test: Principles of Inheritance & Variation - 1 - Question 11
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Direction: In the following questions a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as :

Assertion (A) : Grasshopper shows male heterogamety.

Reason (R) : In grasshopper, males have one X only (XO type).

Detailed Solution: Question 11

Male grasshopper shows XO gametes while female grasshopper shows XX.

Assertion & Reason Test: Principles of Inheritance & Variation - 1 - Question 12
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Direction: In the following questions a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as :

Assertion : In birds, the chromosome composition of the egg determines the sex.

Reason : Female birds are heterogametic.

Detailed Solution: Question 12

In birds, chromosomal composition of the egg determines the sex. This is called genetic sex determination, with females being heterogametic. But being heterogametic is alone not responsible for sex determination. Other factors like specific genes or autosomal, sex chromosome ratio, etc., are responsible.

Assertion & Reason Test: Principles of Inheritance & Variation - 1 - Question 13
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Direction: In the following questions a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as :

Assertion (A) : A cross between a red flower bearing plant and a white flower-bearing plant of Antirrhinum is a case of incomplete dominance.

Reason (R) : This type of cross produces all plants having pink flowers.

Detailed Solution: Question 13

The cross between white and red flower of Antirrhinum shows pink colour in the offspring plant i.e., neither white or red is completely dominant.

Assertion & Reason Test: Principles of Inheritance & Variation - 1 - Question 14
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Direction: In the following questions a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as :

Assertion : Quantitative inheritance is called polygenic inheritance.

Reason : Several genes control the expression of a trait.

Detailed Solution: Question 14

Quantitative inheritance is a type of inheritance controlled by one or more genes in which the dominant alleles have cumulative effect with each dominant allele expressing a part or unit of the trait, the full trait being shown only when all the dominant alleles are present. The genes involved in quantitative inheritance are called polygenes. A polygene is defined as a gene where a dominant allele controls only a unit or partial quantitative expression of a trait.

Assertion & Reason Test: Principles of Inheritance & Variation - 1 - Question 15
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Direction: In the following questions a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as :

Assertion (A) : The offspring of a cross made between the plants having two contrasting characters shows only one character without any blending.

Reason (R): The factor controlling any character is discrete and independent.

Detailed Solution: Question 15

According to law of segregation or law of purity of gametes, factors or alleles of a pair segregate from each other during gamete formation, such that a gamete receives only one of the two factors and do not show any blending.

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About this NEET Practice Test

This test contains 15 MCQs on Assertion & Reason Test: Principles of Inheritance & Variation - 1 with detailed solutions for each question. It is part of the Biology Class 12 course on EduRev, designed to align with the current NEET syllabus. Each solution explains not just the correct answer but also gives you an understanding of the topic — not just to attempt the question but also help you prepare for the exam with practice.

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