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In pea plants, tall plants (T) are dominant over short plants (t). If a heterozygous tall pea plant is crossed with a homozygous recessive short pea plant, what percentage of the offspring is expected to be tall.

(HINT: use a Punnett square to help you with this question)

(1 point)
Responses

75%
75%

0%
0%

25%
25%

50%

1 answer

To determine the percentage of tall offspring when a heterozygous tall pea plant (Tt) is crossed with a homozygous recessive short pea plant (tt), we can use a Punnett square.

  1. Set Up the Punnett Square:
    • Parent 1 (heterozygous tall): Tt
    • Parent 2 (homozygous short): tt

The possible gametes from each parent are:

  • Parent 1 can produce gametes: T or t
  • Parent 2 can only produce gametes: t

Now, we set up the Punnett square:

         t     t
        __________
      |    |    |
     T | Tt | Tt |  
        |    |    |
      |    |    |
     t | tt | tt |  
        |    |    |
  1. Analyze the Results: From the Punnett square, we see the following combinations:
  • Tt (tall)
  • Tt (tall)
  • tt (short)
  • tt (short)
  1. Count the Phenotypes:
  • Tall (Tt): 2 out of 4 (50%)
  • Short (tt): 2 out of 4 (50%)
  1. Calculate the Percentage of Tall Offspring: To find the percentage of tall plants, we take the number of tall offspring over the total number of offspring:

\[ \text{Percentage of tall offspring} = \frac{2}{4} \times 100 = 50% \]

Therefore, the expected percentage of tall offspring is 50%.