Punnette Square

Question 1: Dominance

In pea plants, the allele for tall plants (T) is dominant over the allele for short plants (t). What is the genes percentage for a cross between two heterozygous tall plants (Tt x Tt)?

• 25% TT, 50% Tt, 25% tt

• 50% TT, 25% Tt, 25% tt

• 50% TT, 50% Tt, 0% tt

• 25% TT, 0% Tt, 50% tt

Question 2: Dominance

A homozygous dominant, brown-eyed cat (BB) is crossed with a homozygous recessive blue-eyed  (bb). What are the phenotypes (traits) of the offspring?

• 100% Brown

• 50% Brown, 50% blue

• 100% blue

• 75% Brown, 25% blue

Question 3: Codominance

In chickens, the allele for black feathers (B) and the allele for white feathers (W) are codominant. What would be the phenotype (trait) of the offspring from a cross between a black-feathered chicken (BB) and a white-feathered chicken (WW)?

• 100% Black & White together

• 100% Grey

• 100% all Black

• 100% all White

 

Question 4: Codominance

If a black-feathered chicken (BW) is crossed with a white-feathered chicken (WW), what are the possible phenotypes of the offspring?

• 50% Black & White

  50 % White

• 75% Black & White

  25 % White

• 100% Black & White

• 100% White

Question 5: Incomplete Dominance

In snapdragons, the allele for red flowers (R) is incompletely dominant over the allele for white flowers (r). What is the phenotype (trait) of the offspring from a cross between a red flowered snapdragon (RR) and a white flowered snapdragon (rr)?

• 100% Pink

• 100% Red

• 50% Red, 50% White

• 75% Red, 25% White