PYQ Vault

Dominant and recessive traits

This type of question, asked 4 times: 2022, 2023, 2024, 2025. All 7 questions below, oldest first.

Try each one first, then open its answer.

  1. Question 1

    2022

    6 (a)
    Mendel crossed two pea plants with visible contrasting characteristics and found that there were no half-way characteristics in the plants of F1\mathrm{F_1} progeny. Explain the reason for this observation of Mendel.
  2. Question 2

    2023

    10
    Consider the following two statements : (i) The trait that expresses itself in F1\mathrm{F_1} generation. (ii) The trait that keeps on passing from one generation to another. The appropriate terms for the statements (i) and (ii) respectively are :

    Tap an option to check your answer.

  3. Question 3

    2023

    Two statements are given, one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer from the options given below.
    18
    Assertion (A) : In humans, if gene (B) is responsible for black eyes and gene (b) is responsible for brown eyes, then the colour of eyes of the progeny having gene combination Bb, bb or BB will be black only. Reason (R) : The black colour of the eyes is a dominant trait.

    Tap an option to check your answer.

  4. Question 4

    2024

    23 (a)
    List any two pairs of visible contrasting characters of garden pea plants used by Mendel for his experiments stating the dominant and recessive characters in each pair.
  5. Question 5

    2024

    30
    List two differences between dominant traits and recessive traits. What percentage of pea plants in the F2\mathrm{F_2} generation were with yellow seeds in Mendel’s cross between the pea plants having yellow (YY) and green coloured (yy) seeds ?
  6. Question 6

    2025

    8
    Mendel obtained F2\mathrm{F_2} generation by

    Tap an option to check your answer.

  7. Question 7

    2025

    30
    The lowest part of the ear called earlobe, is closely attached to the side of the head in some of us (Figure ‘X’), and not in others, called free earlobe (Figure ‘Y’). Attached and free earlobes are two variants found in human populations. The gene for free earlobe is dominant over attached earlobes. (a) A man with attached earlobes marries a woman having free earlobes. 50% of their children have free earlobes and 50% have attached earlobes. Explain the inheritance of this trait and write the trait combinations of the progeny. (b) Write the gene combinations of the father and the mother in the above case.