📘 Heredity and Evolution – MCQs (Class 10 Science)

🔹 Part 1: Questions 1–25

Q1. The transmission of characters from parents to offspring is called:

A) Variation
B) Evolution
C) Heredity
D) Genetics

Correct Answer: C) Heredity

Explanation:

• A) Variation → Differences among individuals.
• B) Evolution → Gradual changes over generations.
• ✅ C) Heredity → Transfer of traits from parents to children.
• D) Genetics → Study of heredity, not the process itself.

Q2. Who is regarded as the father of genetics?

A) Darwin
B) Mendel
C) Lamarck
D) Morgan

Correct Answer: B) Mendel

Explanation:

• A) Darwin → Theory of evolution.
• ✅ B) Gregor Mendel → Experimented with pea plants, laws of inheritance.
• C) Lamarck → Theory of acquired characters.
• D) Morgan → Worked on fruit flies.

Q3. In Mendel’s monohybrid cross, the ratio of dominant to recessive in F2 generation is:

A) 1:1
B) 2:1
C) 3:1
D) 9:3:3:1

Correct Answer: C) 3:1

Explanation:

• A) 1:1 → Seen in test cross.
• B) 2:1 → Not applicable.
• ✅ C) Monohybrid F2 → 3 dominant : 1 recessive.
• D) 9:3:3:1 → Dihybrid cross.

Q4. Inheritance of one character does not affect inheritance of another character. This is:

A) Law of segregation
B) Law of dominance
C) Law of independent assortment
D) Theory of acquired characters

Correct Answer: C) Law of independent assortment

Explanation:

• A) Segregation → Alleles separate during gamete formation.
• B) Dominance → One allele masks another.
• ✅ C) Independent assortment → One character does not affect the other.
• D) Acquired characters → Lamarck’s rejected theory.

Q5. The sex of a child in humans is determined by:

A) Mother’s ovum
B) Father’s sperm
C) Placenta
D) Hormones

Correct Answer: B) Father’s sperm

Explanation:

• A) Mother’s ovum → Always X chromosome.
• ✅ B) Sperm carries X or Y → Determines sex.
• C) Placenta → Provides nutrition.
• D) Hormones → Influence growth, not sex determination.

Q6. Which of the following is a recessive trait in pea plants?

A) Tall plant
B) Yellow seed
C) Green seed
D) Round seed

Correct Answer: C) Green seed

Explanation:

• A) Tall → Dominant.
• B) Yellow → Dominant.
• ✅ C) Green → Recessive seed color.
• D) Round → Dominant.

Q7. The observable characters of an organism are called:

A) Genotype
B) Phenotype
C) Alleles
D) Traits

Correct Answer: B) Phenotype

Explanation:

• A) Genotype → Genetic makeup.
• ✅ B) Phenotype → Observable traits (e.g., tall, short).
• C) Alleles → Alternate forms of a gene.
• D) Traits → Features but not the observable expression.

Q8. Which of the following is an acquired character?

A) Eye color
B) Blood group
C) Body weight due to exercise
D) Hair type

Correct Answer: C) Body weight due to exercise

Explanation:

• A, B, D → Inherited genetically.
• ✅ C) Exercise changes weight, not inherited.

Q9. Variations that are inherited from parents are called:

A) Somatic variations
B) Genetic variations
C) Acquired variations
D) Environmental variations

Correct Answer: B) Genetic variations

Explanation:

• A, C, D → Not inherited.
• ✅ B) Genetic variations → Passed from parents to offspring.

Q10. Which of the following decides the sex of a child?

A) XX chromosomes
B) XY chromosomes
C) YY chromosomes
D) XO chromosomes

Correct Answer: B) XY chromosomes

Explanation:

• A) XX → Female.
• ✅ B) XY → Male, hence sperm decides sex.
• C, D → Not possible in humans.

Q11. The physical expression of a pair of contrasting traits is governed by:

A) Dominant allele
B) Recessive allele
C) Both equally
D) None

Correct Answer: A) Dominant allele

Explanation:

• ✅ A) Dominant masks recessive.
• B) Recessive expressed only when homozygous.
• C, D → Not true.

Q12. Who proposed the theory of natural selection?

A) Mendel
B) Lamarck
C) Darwin
D) Morgan

Correct Answer: C) Darwin

Explanation:

• A) Mendel → Heredity.
• B) Lamarck → Acquired characters.
• ✅ C) Darwin → Natural selection theory.
• D) Morgan → Drosophila experiments.

Q13. Evolution is best described as:

A) Sudden appearance of new species
B) Change in DNA only
C) Gradual change in inherited traits over generations
D) Learning new habits

Correct Answer: C) Gradual change in inherited traits over generations

Explanation:

• ✅ C) Evolution → Gradual change in heritable characteristics.
• A, B, D → Incomplete/wrong definitions.

Q14. Which scientist proposed the use and disuse theory?

A) Darwin
B) Mendel
C) Lamarck
D) Wallace

Correct Answer: C) Lamarck

Explanation:

• A) Darwin → Natural selection.
• ✅ C) Lamarck → Organs develop by use, disappear by disuse.
• B, D → Not correct.

Q15. Fossils are preserved remains of:

A) Present-day plants and animals
B) Ancient organisms
C) Microbes only
D) Minerals

Correct Answer: B) Ancient organisms

Explanation:

• ✅ B) Fossils → Evidence of past life forms.
• A, C, D → Wrong definitions.

Q16. Which type of trait is expressed only in homozygous condition?

A) Dominant
B) Recessive
C) Acquired
D) Co-dominant

Correct Answer: B) Recessive

Explanation:

• A) Dominant → Expressed in heterozygous too.
• ✅ B) Recessive → Visible only in homozygous state.
• C, D → Not related.

Q17. Which pair of sex chromosomes do females have?

A) XY
B) XX
C) YY
D) XO

Correct Answer: B) XX

Explanation:

• ✅ B) Females → XX.
• A) Males → XY.
• C, D → Not possible in humans.

Q18. The presence of different forms of a gene is called:

A) Phenotype
B) Genotype
C) Alleles
D) Chromosomes

Correct Answer: C) Alleles

Explanation:

• ✅ C) Alleles → Alternate forms of a gene.
• A, B, D → Wrong definitions.

Q19. In humans, the number of pairs of chromosomes is:

A) 23
B) 46
C) 22
D) 44

Correct Answer: A) 23

Explanation:

• ✅ A) Humans have 23 pairs = 46 chromosomes.
• B) 46 → Total chromosomes, not pairs.
• C, D → Incorrect.

Q20. Which of the following shows acquired characters are not inherited?

A) Darwin’s theory
B) Lamarck’s theory
C) Mendel’s laws
D) Weismann’s experiment with rats

Correct Answer: D) Weismann’s experiment with rats

Explanation:

• ✅ D) Weismann cut tails of rats, offspring still had tails → acquired traits not inherited.
• A, B, C → Different contexts.

Q21. Which of the following is an example of evolution?

A) A student learning cycling
B) Development of resistance in bacteria to antibiotics
C) Growth of muscles by exercise
D) Haircut

Correct Answer: B) Development of resistance in bacteria to antibiotics

Explanation:

• ✅ B) Inherited change in population = Evolution.
• A, C, D → Acquired, not evolution.

Q22. In dihybrid cross, the F2 phenotypic ratio is:

A) 3:1
B) 9:3:3:1
C) 1:2:1
D) 2:1

Correct Answer: B) 9:3:3:1

Explanation:

• ✅ B) Dihybrid F2 → 9:3:3:1 ratio.
• A, C, D → Monohybrid/test cross ratios.

Q23. The process by which new species arise from pre-existing ones is:

A) Heredity
B) Speciation
C) Variation
D) Evolution

Correct Answer: B) Speciation

Explanation:

• ✅ B) Speciation → Formation of new species.
• Others → Broader terms.

Q24. Which of the following is a vestigial organ in humans?

A) Kidney
B) Appendix
C) Liver
D) Heart

Correct Answer: B) Appendix

Explanation:

• ✅ B) Appendix → Vestigial, has no major function now.
• A, C, D → Functional organs.

Q25. The sequence of gradual changes in organisms over geological time is called:

A) Genetics
B) Speciation
C) Evolution
D) Heredity

Correct Answer: C) Evolution

Explanation:

• A, B, D → Different processes.
• ✅ C) Evolution → Gradual change over time.

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