The tomato has a round fruit shape and the red color dominates over the pear-shaped yellow.

The tomato has a round fruit shape and the red color dominates over the pear-shaped yellow. When a diheterozygous plant with round red fruits was crossed with a yellow pear-shaped plant, 48 fruits were obtained. How many red pear-shaped?

Let’s designate the gene that determines the red color of tomatoes as C, then the gene for yellow color will be c. Let’s designate the gene of round-shaped tomatoes as P, then the gene that determines their pear-shaped shape will be p.

Tomato with round red fruits, according to the condition, is diheterozygous – CcPp. It produces sex cells cp, cp, cp and cp.

A tomato with yellow and pear-shaped fruits is ssrr, because homozygosity is an indispensable condition for the phenotypic realization of recessive traits. Such a plant produces sex cells cf.

The offspring obtained from crossing the described tomatoes with each other will include the following options:

tomatoes with yellow pear-shaped fruits (ssrr) – 25%;

tomatoes with red round fruits (СсРр) – 25%;

tomatoes with red pear-shaped fruits (Ссрр) – 25%;

tomatoes with yellow round fruits (ssРр) – 25%.

48 * 0.25 = 12

Answer: 12 plants have a red and pear-shaped fruit.