a tall heterozygous pea plant it crossed with another tall heterozygous pea plant. what is the probability that an offspring will be a short plant?
50%
75%
0%
25%
25%
To determine the probability of an offspring being a short plant, we need to consider the genotype of the tall heterozygous pea plant. In this case, since the plant is heterozygous, it carries one dominant allele (T) and one recessive allele (t) for the tall and short traits, respectively.
When two heterozygous plants (Tt) are crossed, the possible genotypes of their offspring are: TT, Tt, and tt. Among these genotypes, only tt represents a short plant.
Since the offspring has a 1 in 4 chance of inheriting the recessive allele from both parents, the probability that an offspring will be a short plant is 25%. Therefore, the correct answer is 25%.
To determine the probability of an offspring being short, we need to understand the genetic inheritance pattern for the height trait in pea plants. Let's break it down step by step.
1. First, let's assign letters to represent the alleles for the height trait:
- T represents the dominant allele for tall plants
- t represents the recessive allele for short plants
2. Given that both parent plants are heterozygous (Tt) for the height trait, they each carry one dominant and one recessive allele.
3. When these two plants are crossed, their possible combinations of alleles can be determined using a Punnett square. We'll list the potential gametes (sperm and eggs) for each parent along the top and side of the square, and then combine them to find the offspring genotypes in the boxes of the square.
Parent 1 (Tt) can produce gametes T or t.
Parent 2 (Tt) can also produce gametes T or t.
Combining these gametes, we get the following Punnett square:
T t
-----------------
T | TT Tt
t | Tt tt
From the Punnett square, we can see that there are four possible combinations of alleles in the offspring: TT, Tt, Tt, and tt.
4. Now, let's determine the corresponding phenotypes for each genotype:
- TT and Tt genotypes are tall (T is dominant).
- The tt genotype is short (t is recessive).
5. Out of the four possible genotypes, only one contains the tt genotype, which represents a short plant.
6. Therefore, the probability of an offspring being short is 1 out of 4, or 1/4, which is equivalent to 25%.
So, the correct answer is 25%.