Heredity and Evolution (Class 10 Science)

Heredity is the transmission of traits from parents to offspring through genes. Evolution explains the diversity of life through natural selection and adap

Heredity and Evolution (Class 10 Science)

Heredity is the transmission of traits from parents to offspring through genes. Evolution explains the diversity of life through natural selection and adap

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TL;DR: Heredity is the transmission of traits from parents to offspring through genes. Evolution explains the diversity of life through natural selection and…

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Heredity is the transmission of traits from parents to offspring through genes. Evolution explains the diversity of life through natural selection and adap

Heredity and Evolution MCQs with Answers & Explanations

Q1. Who proposed the theory of natural selection?

  1. Jean-Baptiste Lamarck
  2. Gregor Mendel
  3. Charles Darwin ✓ (correct)
  4. Alfred Russel Wallace

Explanation: Charles Darwin proposed the theory of natural selection to explain how species adapt and evolve over time.

Q2. A gene is:

  1. A cell nucleus
  2. A chromosome
  3. A protein
  4. A segment of DNA that codes for a protein or trait ✓ (correct)

Explanation: A gene is a specific segment of DNA that contains instructions for producing a particular protein or trait.

Q3. In a monohybrid cross of Aa x Aa, what is the probability of the recessive phenotype?

  1. 25% ✓ (correct)
  2. 75%
  3. 50%
  4. 100%

Explanation: In Aa x Aa, the offspring ratio is 1 AA : 2 Aa : 1 aa. Only aa shows the recessive phenotype, which is 25% of offspring.

Q4. DNA stands for:

  1. Deoxyribose Nucleic Acid
  2. Deoxyribonucleic Acid ✓ (correct)
  3. Diribonucleic Acid
  4. Deoxyribose Nitrogen Acid

Explanation: DNA stands for deoxyribonucleic acid and is the molecule that stores genetic information.

Q5. The process by which organisms adapt to their environment over generations is called:

  1. Variation
  2. Inheritance
  3. Natural selection ✓ (correct)
  4. Mutation

Explanation: Natural selection is the mechanism by which organisms with advantageous traits survive and reproduce more successfully.

Q6. Which of the following is evidence for evolution?

  1. Fossil records
  2. Comparative anatomy
  3. DNA similarity in organisms
  4. All of the above ✓ (correct)

Explanation: Fossil records show species change over time, comparative anatomy reveals structural similarities, and DNA proves genetic relationships between species.

Q7. A dominant trait is one that:

  1. Appears in both parents
  2. Always appears in offspring
  3. Requires two copies of the allele
  4. Masks the recessive trait in heterozygotes ✓ (correct)

Explanation: A dominant allele expresses its phenotype in both homozygous (AA) and heterozygous (Aa) conditions, masking the recessive allele.

Q8. The variation in organisms is caused by:

  1. Both genetic variation and environmental factors ✓ (correct)
  2. Only environmental factors
  3. Only mutation
  4. Only genetic factors

Explanation: Phenotypic variation results from both genetic differences (alleles) and environmental influences on development and physiology.

Q9. If an organism has the genotype AaBb, how many different gametes can it produce?

  1. 8
  2. 4 ✓ (correct)
  3. 2
  4. 16

Explanation: An organism with genotype AaBb can produce 4 different gametes: AB, Ab, aB, ab (2^n where n=2 heterozygous loci).

Q10. Vestigial structures in organisms are evidence for:

  1. Spontaneous generation
  2. Lamarckian evolution
  3. Common ancestry ✓ (correct)
  4. Divine creation

Explanation: Vestigial structures (like human tailbones) are remnants from ancestral forms and provide evidence that organisms share common ancestors.

Q11. What is the unit of heredity called?

  1. Allele
  2. Chromosome
  3. Nucleus
  4. Gene ✓ (correct)

Explanation: A gene is the unit of heredity that carries information for specific traits and is passed from parents to offspring.

Q12. Who is known as the father of genetics?

  1. Gregor Mendel ✓ (correct)
  2. Charles Darwin
  3. Robert Hooke
  4. Louis Pasteur

Explanation: Gregor Mendel conducted experiments on pea plants and established the fundamental laws of inheritance.

Q13. In Mendel's monohybrid cross, what was the phenotypic ratio in F2 generation?

  1. 1:1
  2. 3:1 ✓ (correct)
  3. 9:3:3:1
  4. 1:2:1

Explanation: The 3:1 ratio appeared in the F2 generation showing that the dominant trait appeared three times more often than the recessive.

Q14. What are alleles?

  1. Recessive genes only
  2. Different genes on same chromosome
  3. Different forms of the same gene ✓ (correct)
  4. Dominant genes only

Explanation: Alleles are alternate forms of a gene that code for different versions of the same trait.

Q15. Which of the following is a dominant trait in humans?

  1. Red hair
  2. Blue eyes
  3. Attached earlobes
  4. Rolling tongue ✓ (correct)

Explanation: The ability to roll the tongue is a dominant trait, requiring only one dominant allele for expression.

Q16. What is a homozygous genotype?

  1. AA or aa ✓ (correct)
  2. Aa or Bb
  3. Different alleles
  4. Aa

Explanation: Homozygous means both alleles are the same, either AA (homozygous dominant) or aa (homozygous recessive).

Q17. In a test cross, what is the ratio obtained when a homozygous dominant is crossed with homozygous recessive?

  1. 3:1
  2. All dominant ✓ (correct)
  3. 1:1
  4. 1:2:1

Explanation: A test cross with a homozygous recessive produces all dominant offspring in the F1 generation.

Q18. Which chromosome pair determines the sex in humans?

  1. Chromosome 10
  2. Chromosome 1
  3. Chromosome 23 ✓ (correct)
  4. Chromosome 5

Explanation: Chromosome 23 is the sex chromosome pair (XX for females, XY for males) that determines biological sex.

Q19. What is a variation in biology?

  1. Change in environment
  2. Disease in organism
  3. Mutation in genes
  4. Differences between individuals of same species ✓ (correct)

Explanation: Variation refers to the differences in traits among individuals of the same species due to genetic and environmental factors.

Q20. Which process leads to evolution according to Darwin?

  1. Natural selection ✓ (correct)
  2. Mutation
  3. Genetic drift
  4. Adaptation

Explanation: Natural selection is the mechanism Darwin proposed where organisms with favorable traits survive and reproduce more successfully.

Frequently Asked Questions

What is the difference between genotype and phenotype?

Genotype is the genetic makeup of an organism (e.g., Aa), while phenotype is the observable characteristics resulting from the genotype and environment (e.g., brown eyes).

How does natural selection drive evolution?

Organisms with traits advantageous in their environment survive and reproduce more successfully, passing those traits to offspring. Over many generations, advantageous traits become more common in the population, leading to evolutionary change.

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