Question

in pea plants tall dominate short. which of the following would be the most accurate representation of a population of 1000 pea plants produced by crossing only heterozygous plants with each other.

○ 740 tall and 260 short

○ 750 short and 250 tall

○ all the offspring would be tall

○ 500 short and 500 tall

Explanation:

Step1: Recall Mendelian Genetics

When heterozygous (Tt) pea plants are crossed, the Punnett square gives a genotypic ratio of \(TT:Tt:tt = 1:2:1\) and phenotypic ratio of tall (TT + Tt) : short (tt) = \(3:1\).

Step2: Calculate Expected Numbers

For a population of 1000 plants, the expected number of tall plants is \(\frac{3}{4} \times 1000 = 750\) (approx) and short plants is \(\frac{1}{4} \times 1000 = 250\). Among the options, 740 Tall and 260 short is closest to this 3:1 ratio (due to random sampling variation in real populations). The other options: 750 short and 250 tall is incorrect (short should be less), all tall is wrong (tt will be short), 500 - 500 is a 1:1 ratio which is not for heterozygous cross.

Answer:

740 Tall and 260 short