21. (i) Green and red colour of seeds recessive and dominant traits, respectively. Out of F and F2, in which generation will the green seeds appear, if both parents are hot hybrid. Explain by giving reason.
(ii) Dead remains of two species A and B were buried. Later only A's body was found to be fossilised, but not B's. Give reason to explain it. (iii) Species A shares ten characteristics with species B and species C shares fifteen characteristic with species D. Which of the two pairs share closer relation?
Answers
Answer:
(i) In F2 generation, 1 progeny will have green seeds (1 out of 4).
(ii) Only remains of A must have been in conditions necessary for fossilization.
(iii) Species C and D share a closer relation.
Explanation:
(i) Using Punnett's square method, we can assign red seeds a capital R, and green seeds small r.
With both parents crossed, we get Rr in F1 generation.
With cross of Rr × Rr, in F2 generation we get RR, Rr, Rr, rr
Homozygous red -> 1 (RR)
Heterozygous red -> 2 (Rr)
Homozygous green -> 1 (rr)
(ii) Only remains of A must have been in position of hot mud to slow down the decomposition process and after hardening it retains the impression of organism A. It also requires high pressure to fossilize the remains.
(iii) When 2 species have more number of common characteristics, it indicates closer relations. Thus, having common ancestry.