Question

Tall is dominant to short among pea plants. Choose appropriate symbols for these two traits and using these symbols write out a cross between true-breeding tall plants and true-breeding short plants. Be sure to include a legend and indicate what percentage of the offspring would be expected to show a given trait.

a. If the offspring were allowed to self- fertilize, what phenotypes and genotypes would be expected among the offspring and in what proportion? Using the symbols selected in the original problem, write out this cross and the resulting offspring. Please use Punnett square for this problem.

b. If the offspring were mated to true-breeding short plants, what phenotypes and genotypes would be expected among the offspring and in what proportion? Using the symbols selected in the original problem, write out this cross and the resulting offspring. What is this kind of cross called?

c. If the offspring were mated to true-breeding tall plants what phenotypes and genotypes would be expected among the offspring and in what proportion? Using the symbols selected in the original problem write out this cross and the resulting offspring.

Answer 1

See the answer below

Step-by-step explanation:

Let the tallness be represented by T and the shortness by t.

True-breeding tall plant = TT

True-breeding short plant = tt

TT x tt

Tt Tt Tt TT

Genotypic ratio of offspring: 100% Tt

Phenotypic ratio of offspring: 100% tall (see the first attached image for the Punnet's square analysis)

(a) See the second attached image for the Punnet's square analysis.

Tt x Tt

TT Tt Tt tt

Expected genotypes

• 1/4 TT
• 1/2 Tt
• 1/4 tt

Expected phenotypes

• Tall - 75%
• Short - 25%

(b) Tt x tt

Tt Tt tt tt

Expected genotypes

• 1/2 Tt
• 1/2 tt

Expected phenotypes

• Tall - 50%
• Short - 50%

The kind of cross if referred to as test crossing.

(c) Tt x TT

TT TT Tt Tt

Expected genotypes

• 1/2 TT
• 1/2 Tt

Expected phenotypes

• Tall - 100%