Thursday, October 14, 2021

Heredity and Evolution | Class 10 | Activity 9.2 with Solution

Heredity and Evolution | Activities in Text Book with Solution

Activity 9.2

In Fig. 9.3, what experiment would we do to confirm that the F2 generation did in fact have a 1:2:1 ratio of TT, Tt and tt trait combinations?


✅ Answer: It is possible through an experiment called Test cross. It is the cross between plants of unknown genotypes with recessive plants (tt). Here, the genotypes of tall plants are unknown. So they are crossed with recessive (short) plants.

If the tall plant is pure (homozygous), it produces only tall offspring (TT x tt → Tt).

If the tall plant is impure (heterozygous), it produces 50% tall offspring & 50% dwarf offspring (Tt x tt → Tt & tt). Thus we can confirm the F2 genotypic ratio is 1:2:1.

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