Heredity — Class 10 MCQs with Answers

Heredity — important questions & MCQs with answers (Class 10 Science (Biology))

14 solved questions from this chapter's difficulty levels, each with its answer and explanation. The other 76 are timed and scored when you sign in.

1. Q1Easy

   Father of genetics:

   A.Darwin

   B.Watson

   C.Mendel✓ Correct

   D.Lamarck

   Answer: C. Mendel

   Explanation: Gregor Mendel's 1860s pea-plant experiments uncovered the basic laws of inheritance, earning him the title father of genetics; Darwin explained evolution by natural selection, a different question.

2. Q2Easy

   Heredity is the:

   A.Random change in cells

   B.Process of growth

   C.Loss of features

   D.Transmission of characters from parents to offspring✓ Correct

   Answer: D. Transmission of characters from parents to offspring

   Explanation: Heredity is the process by which characters/traits are passed from parents to offspring through genes on chromosomes, explaining why children resemble their parents rather than random change.

3. Q3Easy

   Sex of the child in humans is determined by:

   A.The ovum

   B.The sperm (carrying X or Y)✓ Correct

   C.Both equally

   D.Hormones at random

   Answer: B. The sperm (carrying X or Y)

   Explanation: In humans the ovum always carries an X chromosome, so it is the sperm — carrying either X or Y — that decides whether the child is a girl or a boy.

4. Q4Easy

   Gradual change in characteristics of living organisms over generations is called:

   A.Evolution✓ Correct

   B.Heredity

   C.Adaptation

   D.Reproduction

   Answer: A. Evolution

   Explanation: Evolution is the gradual, generation-by-generation change in the inherited characteristics of a population, driven by variation and selection — distinct from heredity, which passes traits on unchanged.

5. Q5Easy

   Mendel performed his experiments on:

   A.Garden pea (Pisum sativum)✓ Correct

   B.Maize

   C.Sunflower

   D.Wheat

   Answer: A. Garden pea (Pisum sativum)

   Explanation: Mendel used garden pea (Pisum sativum) because it shows clear, easily tracked contrasting traits like tall/dwarf and round/wrinkled seeds, and can be self- or cross-pollinated at will.

6. Q6Easy

   A unit of inheritance is called a:

   A.Gene✓ Correct

   B.Cell

   C.Chromosome

   D.DNA strand

   Answer: A. Gene

   Explanation: A gene is a specific segment of DNA on a chromosome that codes for a particular trait and is the basic unit of inheritance; a chromosome carries many genes, not just one.

7. Q7Medium

   Phenotypic ratio of F2 in a monohybrid cross:

   A.1:1

   B.3:1✓ Correct

   C.9:3:3:1

   D.1:2:1

   Answer: B. 3:1

   Explanation: Selfing F₁ (Tt) gives F₂ genotypes 1 TT : 2 Tt : 1 tt; since TT and Tt both look tall, phenotypes appear as 3 tall : 1 dwarf — this phenotypic ratio differs from the 1:2:1 genotypic one.

8. Q8Medium

   Chromosomes are made of:

   A.Carbohydrates

   B.DNA and proteins✓ Correct

   C.Lipids

   D.Only DNA

   Answer: B. DNA and proteins

   Explanation: Chromosomes consist of a long DNA molecule tightly wound around histone proteins, which package and organise the genetic material inside the nucleus — not carbohydrates or lipids.

9. Q9Medium

   Chromosome combination in a human male:

   A.XX

   B.X only

   C.YY

   D.XY✓ Correct

   Answer: D. XY

   Explanation: Human males carry one X and one Y chromosome (XY), while females carry two X chromosomes (XX); the Y chromosome, inherited only from the father, triggers male development.

10. Q10Medium

    Older fossils are found in:

    A.Floating in water

    B.Surface layers

    C.Deeper layers of rock✓ Correct

    D.On trees

    Answer: C. Deeper layers of rock

    Explanation: By the geological principle that rock layers build up over time, undisturbed deeper strata are older than surface layers, so deeper layers hold the older fossils.

11. Q11Medium

    F₂ phenotypic ratio in a dihybrid cross is:

    A.9 : 3 : 3 : 1✓ Correct

    B.3 : 1

    C.1 : 1

    D.1 : 2 : 1

    Answer: A. 9 : 3 : 3 : 1

    Explanation: When two gene pairs assort independently in a dihybrid cross, F₂ offspring appear in a 9:3:3:1 phenotypic ratio — the two-gene analogue of the 3:1 ratio seen in a monohybrid cross.

12. Q12Hard

    Phenotypic ratio of F2 in a dihybrid cross:

    A.9:3:3:1✓ Correct

    B.3:1

    C.1:1:1:1

    D.1:2:1

    Answer: A. 9:3:3:1

    Explanation: In a dihybrid cross like RrYy × RrYy, the two gene pairs assort independently, giving F₂ phenotypes in a 9 (both dominant) : 3 : 3 : 1 (both recessive) ratio, unlike the 3:1 of a single-gene cross.

13. Q13Hard

    In a monohybrid cross of two Tt plants, the fraction of the offspring expected to be short is:

    A.1/4✓ Correct

    B.1

    C.1/2

    D.3/4

    Answer: A. 1/4

    Explanation: The F2 combinations occur as TT, Tt, Tt and tt, so one in four is short.

14. Q14Hard

    The sex of a child is determined by:

    A.The mother

    B.The father (X or Y sperm)✓ Correct

    C.Both equally

    D.Random environment

    Answer: B. The father (X or Y sperm)

    Explanation: The mother's ovum always carries an X chromosome, but the father's sperm carries either X or Y; whichever sperm fertilises the egg fixes the child's sex, so the father's contribution decides it.

Heredity — FAQs

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