A tall plant (TT) is crossed with a short plant (tt). If the tall F1 pea plants are allowed to self-pollinate, what will the offspring be?
A. The offspring will be of medium height.
B. All of the offspring will be tall.
C. All of the offspring will be short.
D. The offspring can be tall or short.
Answer (3)
D) The offspring can be tall or short.
It's helpful to use a Punnet Square in this situation. We know that the F1 plants are all Tt (heterozygous) because they have to get a T from the TT parent and a t from the tt parent. Now we cross the Tt plants:
T | t | T | TT | Tt | t | Tt | tt | So, there will be some plants that are tall (TT or Tt) and some plants that are short (tt). Hope this helps! :)
The correct option is D.) the offspring can be tall or short.
When a tall plant with genotype TT (homozygous dominant) is crossed with a short plant with genotype tt (homozygous recessive), all of the F1 generation are heterozygous (Tt) and tall. If these tall F1 pea plants are allowed to self-pollinate, the F2 generation will have four possible combinations of alleles: TT, Tt, tT, or tt.
According to the laws of probability, there will be a 75% chance that the offspring will have at least one dominant T allele and be tall (TT or Tt), and a 25% chance of being homozygous recessive tt and therefore, short.
The phenotype of a pea plant that is homozygous dominant (TT) for the tall trait is tall, and the phenotype for a pea plant that is heterozygous (Tt) is also tall. The recessive phenotype of being short will only be expressed when the plant is homozygous recessive (tt).
Dihybrid crosses involve two traits, but this question deals with a monohybrid cross, considering only one trait, which is height in pea plants.
When a tall plant (TT) is crossed with a short plant (tt), all offspring in the F1 generation will be tall (Tt). When these tall plants self-pollinate, the ratio of tall to short offspring will be 3:1, so the answer is that the offspring can be tall or short. The correct answer is D.
;
