Test cross involves-
- Crossing between two F1 hybrids
- Crossing the F1 hybrid with a double recessive genotype
- Crossing between two genotypes with recessive trait
- Crossing between two genotypes with dominant trait
Answer
(2) Crossing the F1 hybrid with a double recessive genotype
Solution
As per NCERT, in a test cross an organism showing the dominant phenotype (whose genotype is to be determined) is crossed with the recessive parent instead of self-crossing.
⇒ For a dihybrid F1 (RrYy), the recessive parent is the double recessive rryy.
⇒ RrYy rryy 1 : 1 : 1 : 1, which directly reveals the gametes of the hybrid.
∴ A test cross involves crossing the F1 hybrid with a double recessive genotype.
Answer: (2)