Mendel's Laws, DNA, Sex Determination and Evolution

Attempt the quiz above first, then review every question with its correct answer and a short explanation below.

1. Q1.The Father of Genetics is:

   • A.Gregor Mendel✓ Correct Answer
   • B.Charles Darwin
   • C.Thomas Morgan
   • D.Watson

   Explanation: He worked on pea plants in the 1860s.

2. Q2.Mendel conducted his experiments on:

   • A.maize
   • B.fruit flies
   • C.wheat
   • D.garden pea plants✓ Correct Answer

   Explanation: He studied seven pairs of contrasting traits.

3. Q3.The double helix model of DNA was proposed by:

   • A.Mendel and Morgan
   • B.Hooke and Brown
   • C.Darwin and Wallace
   • D.Watson and Crick✓ Correct Answer

   Explanation: They proposed it in 1953.

4. Q4.Humans have how many pairs of chromosomes?

   • A.22
   • B.24
   • C.46
   • D.23✓ Correct Answer

   Explanation: One pair is the sex chromosomes.

5. Q5.The theory of natural selection was proposed by:

   • A.Lamarck
   • B.Mendel
   • C.Charles Darwin✓ Correct Answer
   • D.Pasteur

   Explanation: Alfred Russel Wallace independently reached the same idea.

6. Q6.Genes are located on the:

   • A.ribosomes
   • B.chromosomes✓ Correct Answer
   • C.lysosomes
   • D.cell wall

   Explanation: They are segments of DNA.

7. Q7.In humans, the combination of sex chromosomes in a male is:

   • A.XY✓ Correct Answer
   • B.XX
   • C.XO
   • D.YY

   Explanation: Females are XX.

8. Q8.A trait that is expressed even in the heterozygous condition is called:

   • A.recessive
   • B.dominant✓ Correct Answer
   • C.hybrid
   • D.mutant

   Explanation: A dominant trait masks the recessive one in a heterozygote.

9. Q9.The phenotypic ratio in the F2 generation of a monohybrid cross is:

   • A.1:1
   • B.9:3:3:1
   • C.1:2:1
   • D.3:1✓ Correct Answer

   Explanation: The phenotypic ratio is 3:1: three show the dominant trait for every one recessive.

10. Q10.Haemophilia is a:

    • A.dominant autosomal disorder
    • B.viral disease
    • C.sex-linked recessive disorder✓ Correct Answer
    • D.vitamin deficiency

    Explanation: It is carried on the X chromosome.

11. Q11.Colour blindness is an example of:

    • A.a bacterial disease
    • B.an X-linked recessive disorder✓ Correct Answer
    • C.a dominant disorder
    • D.a nutritional disorder

    Explanation: It is more common in males.

12. Q12.Lamarck's theory of evolution is based on the:

    • A.survival of the fittest
    • B.inheritance of acquired characters✓ Correct Answer
    • C.mutation only
    • D.genetic drift only

    Explanation: The long neck of the giraffe was his classic example.

13. Q13.Fossils are evidence of:

    • A.organic evolution✓ Correct Answer
    • B.photosynthesis
    • C.digestion
    • D.pollination

    Explanation: They record past life forms in rocks.

14. Q14.The forelimbs of a human and the wing of a bat are examples of:

    • A.analogous organs
    • B.vestigial organs
    • C.homologous organs✓ Correct Answer
    • D.rudimentary organs

    Explanation: They share the same basic structure but differ in function.

15. Q15.The wings of a bird and an insect are examples of:

    • A.homologous organs
    • B.vestigial organs
    • C.analogous organs✓ Correct Answer
    • D.genes

    Explanation: They perform the same function but have different origins.

16. Q16.Darwin's book 'On the Origin of Species' was published in:

    • A.1859✓ Correct Answer
    • B.1809
    • C.1900
    • D.1953

    Explanation: It set out the theory of natural selection.

17. Q17.The phenotypic ratio in the F2 generation of a dihybrid cross is:

    • A.3:1
    • B.1:2:1
    • C.1:1:1:1
    • D.9:3:3:1✓ Correct Answer

    Explanation: It follows Mendel's law of independent assortment.

18. Q18.The nitrogenous base found in RNA but not in DNA is:

    • A.thymine
    • B.uracil✓ Correct Answer
    • C.adenine
    • D.guanine

    Explanation: Uracil replaces thymine in RNA.

19. Q19.Down syndrome is caused by:

    • A.an extra copy of chromosome 21✓ Correct Answer
    • B.a missing X chromosome
    • C.a viral infection
    • D.a vitamin deficiency

    Explanation: It is called trisomy 21.

20. Q20.Genetic engineering mainly involves the use of:

    • A.grafting only
    • B.tissue culture only
    • C.recombinant DNA technology✓ Correct Answer
    • D.cross-pollination only

    Explanation: Genes from one organism are inserted into another.