In certain plants, tall is dominant to short. If a heterozygous plant is crossed with a homozygous tall plant, what is the probability that the offspring will be short?

A) 1

B) 1/2

C) 1/4

D) 1/6

E) 0

The answer is E) 0.

If:

A - dominant allele,

a - recessive allele,

then:

AA - dominant homozygous (tall),

aa - recessive homozygous (short),

Aa - heterozygous (tall).

A heterozygous plant (Aa) is crossed with a homozygous tall plant (AA):

Parental generation: Aa x AA

F1 generation: AA AA Aa Aa

All of the offspring is tall (AA or Aa), since tall is dominant to short.

There is no chance for offspring to be short (aa).