10th Students Heredity NCERT Solution given Answers

Genetics Q&A for Class 10

1. A Mendelian experiment consisted of breeding tall pea plants bearing violet flowers with short pea plants bearing white flowers. The progeny all bore violet flowers, but almost half of them were short. This suggests that the genetic make-up of the tall parent can be depicted as

  • (a) TTWW
  • (b) TTww
  • (c) TtWW
  • (d) TtWw

Answer: (c) TtWW

Explanation: Violet (W) is dominant over white (w), and all F1 plants bear violet flowers, so the tall parent must be homozygous WW. Tall (T) is dominant over short (t), and half the progeny are short, so the tall parent must be heterozygous Tt.

2. A study found that children with light-coloured eyes are likely to have parents with light-coloured eyes. On this basis, can we say anything about whether the light eye colour trait is dominant or recessive? Why or why not?

Answer: We cannot conclude whether light-coloured eyes are dominant or recessive solely from this observation. Phenotypic resemblance in families may reflect shared alleles, but without controlled crosses or pedigree analysis we can’t determine the pattern of inheritance or rule out polygenic influences.

3. Outline a project which aims to find the dominant coat colour in dogs.

Answer:

  • Select two pure-bred dog populations differing in coat colour (for example, black and white).
  • Mate several black-coated dogs with white-coated dogs and record the coat colour of all F1 puppies.
  • If one colour appears in all F1 progeny, that colour is likely dominant.
  • To confirm, intercross F1 individuals and observe F2 ratios: a 3 : 1 ratio (dominant : recessive) supports a single-gene dominant trait.

4. How is the equal genetic contribution of male and female parents ensured in the progeny?

Answer: During gamete formation, meiosis halves the chromosome number so each egg and sperm carries one allele of every gene. Fertilization then fuses one egg and one sperm, restoring the diploid number and ensuring that the offspring inherit exactly half their genes from the mother and half from the father.

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