Here are the answers to your questions from the Heredity chapter (Class 10, CBSE, NCERT):
✅ Q1.
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:
🎯 (c) TtWW
📖 Explanation:
- All progeny had violet flowers, meaning the tall parent must have homozygous dominant (WW) for flower color.
- Almost half were short, which means the tall parent was heterozygous (Tt) for height.
- Hence: TtWW
✅ Q2.
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:
No, we cannot conclude whether the light eye color is dominant or recessive just from this observation.
We need to know if parents with light eyes can also have children with dark eyes, or if two dark-eyed parents can have a light-eyed child.
Only then can the dominance/recessiveness be determined.
✅ Q3.
Outline a project which aims to find the dominant coat colour in dogs.
📝 Answer:
🔷 Select two pure-breeding (homozygous) dogs of different coat colors (e.g., black and brown).
🔷 Cross them to produce the F₁ generation.
🔷 Observe the coat color of the F₁ pups.
- If all pups have the same color, that color is likely dominant.
🔷 To confirm, allow F₁ pups to interbreed and observe the F₂ generation. - If the F₂ generation shows a 3:1 ratio, the color seen in the F₁ is dominant.
✅ Q4.
How is the equal genetic contribution of male and female parents ensured in the progeny?
📝 Answer:
- Each parent contributes one gamete (sperm or egg), which is haploid (has half the number of chromosomes).
- During fertilization, these two gametes combine to form a diploid zygote.
- Hence, the offspring gets half the genetic material from the mother (via egg) and half from the father (via sperm).
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