Mendel’s laws
Answers are for parents and teachers.
1
Black (B) is dominant over brown (b) in rabbits. If Bb × Bb gives 24 young, how many brown are expected? (Number only.)
6
2
Write the cross Aa × Aa using a Punnett square.
Gametes A, a and A, a. Offspring: AA, Aa, Aa, aa. Phenotype 3 : 1, genotype 1 : 2 : 1.
3
A yellow (A) round (B) pea AaBb is crossed with aabb. State the offspring phenotypes.
Yellow round, yellow wrinkled, green round, green wrinkled – 1 : 1 : 1 : 1.
4
How many kinds of gametes does an AaBbCc organism form? (Number only.)
8
5
Define phenotype and genotype and give one example.
Genotype is the sum of all genes (Aa); phenotype is the traits expressed (yellow seed). The same phenotype can have different genotypes: AA and Aa are both yellow.