📘 Heredity and Evolution – MCQs (Class 10 Science)

🔹 Part 2: Questions 26–50

Q26. The term “phenotype” refers to:

A) Genetic constitution
B) Physical appearance
C) Chromosomal number
D) DNA sequence

Correct Answer: B) Physical appearance

Explanation:

• A) Genotype → Genetic constitution.
• ✅ B) Phenotype → Observable characters (tall/short, round/wrinkled).
• C) Chromosomal number → Not phenotype.
• D) DNA sequence → Genetic material.

Q27. The fossil of Archaeopteryx is considered important because it shows:

A) Evolution from reptiles to mammals
B) Evolution from fish to amphibians
C) Evolution from reptiles to birds
D) Evolution from amphibians to reptiles

Correct Answer: C) Evolution from reptiles to birds

Explanation:

• A, B, D → Wrong stages.
• ✅ C) Archaeopteryx → Had features of both reptiles (teeth, tail) and birds (feathers).

Q28. Which of the following is NOT a factor that leads to evolution?

A) Variations
B) Natural selection
C) Inheritance
D) Balanced diet

Correct Answer: D) Balanced diet

Explanation:

• A, B, C → All contribute to evolution.
• ✅ D) Balanced diet → Affects health, not evolution.

Q29. In human beings, sex is determined by:

A) 21st chromosome pair
B) 22nd chromosome pair
C) 23rd chromosome pair
D) Mitochondrial DNA

Correct Answer: C) 23rd chromosome pair

Explanation:

• A, B → Autosomes.
• ✅ C) 23rd → Sex chromosomes (XX female, XY male).
• D) Mitochondrial DNA → Inherited from mother, not sex-determining.

Q30. The theory of inheritance of acquired characters was proposed by:

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

Correct Answer: C) Lamarck

Explanation:

• ✅ C) Lamarck → Use & disuse theory (giraffes’ long neck).
• A, B, D → Different contributions.

Q31. A pair of contrasting traits in pea plant studied by Mendel was:

A) Tall and short
B) Pink and red flowers
C) Broad and narrow leaves
D) Thick and thin stem

Correct Answer: A) Tall and short

Explanation:

• ✅ A) Height was one of the seven traits studied.
• B, C, D → Not Mendel’s chosen traits.

Q32. Which of the following is a vestigial organ in human beings?

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

Correct Answer: B) Appendix

Explanation:

• ✅ B) Appendix → No significant function, proof of evolution.
• A, C, D → Vital organs.

Q33. Which cross would result in all heterozygous tall plants (Tt)?

A) TT × TT
B) TT × tt
C) Tt × Tt
D) tt × tt

Correct Answer: B) TT × tt

Explanation:

• A) TT × TT → All TT.
• ✅ B) TT × tt → All Tt (heterozygous tall).
• C) Tt × Tt → 3 tall : 1 short.
• D) tt × tt → All short.

Q34. A cross between a tall plant (Tt) and a dwarf plant (tt) gives offspring ratio:

A) 1:1
B) 2:1
C) 3:1
D) All tall

Correct Answer: A) 1:1

Explanation:

• ✅ A) Tt × tt → 50% Tt (tall), 50% tt (short).
• B, C, D → Incorrect ratios.

Q35. The gradual development of organisms from pre-existing simple forms over long period of time is:

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

Correct Answer: B) Evolution

Explanation:

• ✅ B) Evolution → Gradual change in species.
• A, C, D → Different processes.

Q36. Which of the following is NOT an example of evolution?

A) Industrial melanism in moths
B) Development of long neck in giraffes
C) A student learning swimming
D) Resistance of bacteria to antibiotics

Correct Answer: C) A student learning swimming

Explanation:

• A, B, D → Evolutionary changes.
• ✅ C) Learning swimming → Acquired, not inherited.

Q37. Who discovered the laws of inheritance?

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

Correct Answer: B) Mendel

Explanation:

• ✅ B) Mendel → Father of genetics, pea plant experiments.
• A, C, D → Other contributions.

Q38. Which structure carries hereditary information in organisms?

A) Mitochondria
B) Ribosome
C) Chromosomes
D) Lysosome

Correct Answer: C) Chromosomes

Explanation:

• A) Mitochondria → Energy.
• B) Ribosome → Protein synthesis.
• ✅ C) Chromosomes → Carry DNA & genes.
• D) Lysosome → Digestion.

Q39. The study of fossils is called:

A) Embryology
B) Paleontology
C) Taxonomy
D) Genetics

Correct Answer: B) Paleontology

Explanation:

• ✅ B) Paleontology → Study of fossils.
• A, C, D → Other branches of biology.

Q40. Which scientist is associated with “Origin of Species”?

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

Correct Answer: B) Darwin

Explanation:

• ✅ B) Darwin wrote “On the Origin of Species” in 1859.
• A, C, D → Different scientists.

Q41. The human hand, cat’s paw and a whale’s flipper are examples of:

A) Analogous organs
B) Vestigial organs
C) Homologous organs
D) Fossils

Correct Answer: C) Homologous organs

Explanation:

• ✅ C) Same basic structure, different functions → Homologous.
• A) Analogous → Similar function, different structure.
• B) Vestigial → Rudimentary.
• D) Fossils → Preserved remains.

Q42. Which one is an example of analogous organs?

A) Forelimb of frog and lizard
B) Wing of bird and bat
C) Wing of insect and bird
D) Hand of man and whale’s flipper

Correct Answer: C) Wing of insect and bird

Explanation:

• A, B, D → Homologous organs.
• ✅ C) Function same (flying) but different structures.

Q43. A cross between red flower plant (RR) and white flower plant (rr) gives pink flowers (Rr). This is:

A) Law of dominance
B) Incomplete dominance
C) Co-dominance
D) Mutation

Correct Answer: B) Incomplete dominance

Explanation:

• A) Dominance → One masks other.
• ✅ B) Incomplete dominance → Neither allele completely dominant, results in blending.
• C) Co-dominance → Both alleles expressed equally.
• D) Mutation → Sudden change in DNA.

Q44. A genetic makeup of an individual is called:

A) Genotype
B) Phenotype
C) Allele
D) Character

Correct Answer: A) Genotype

Explanation:

• ✅ A) Genotype → Genes an organism carries.
• B) Phenotype → Physical traits.
• C) Allele → Alternative gene form.
• D) Character → Observable feature.

Q45. Speciation can occur due to:

A) Geographic isolation
B) Genetic drift
C) Natural selection
D) All of the above

Correct Answer: D) All of the above

Explanation:

• ✅ D) Speciation influenced by isolation, genetic drift, natural selection.
• A, B, C → Partial factors.

Q46. Which of the following is NOT a factor responsible for evolution?

A) Natural selection
B) Genetic drift
C) Mutation
D) Balanced diet

Correct Answer: D) Balanced diet

Explanation:

• ✅ D) Diet → Individual health, not evolution.
• A, B, C → Important evolutionary factors.

Q47. Who disproved Lamarck’s theory of acquired characters by rat experiment?

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

Correct Answer: C) Weismann

Explanation:

• ✅ C) Weismann → Cut tails of rats for generations, but offspring still had tails.
• A, B, D → Not involved.

Q48. The evidence of evolution from embryological studies is based on:

A) Similarities in early embryo development of organisms
B) Similarities in adult forms
C) Fossil structure
D) DNA sequencing

Correct Answer: A) Similarities in early embryo development of organisms

Explanation:

• ✅ A) Embryology → Early stages of vertebrates look similar.
• B, C, D → Other evidences.

Q49. A sudden change in a gene is known as:

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

Correct Answer: B) Mutation

Explanation:

• ✅ B) Mutation → Sudden change in DNA/gene sequence.
• A, C, D → Broader processes.

Q50. The study of similarities and differences in body structures of organisms is called:

A) Genetics
B) Embryology
C) Comparative anatomy
D) Paleontology

Correct Answer: C) Comparative anatomy

Explanation:

• ✅ C) Comparative anatomy → Studies homologous/analogous organs.
• A, B, D → Different fields.

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