Question

A heterozygous plant with red flowers and tall height was crossed with a recessive plant having white flowers and dwarf height. What will be the percentage of plants having dwarf height?

(a) 25%
(b) 75%
(c) 50%
(d) 12.5%

Answer 1

Using a Punnett square, the genotypes of the offspring from a cross between a heterozygous tall plant with red flowers and a recessive dwarf plant with white flowers show that 50% of the offspring will be dwarf in height.

Step-by-step explanation:

To determine the percentage of plants having dwarf height after a cross between a heterozygous tall plant with red flowers (represented as RrTt, where 'R' is red, 'r' is white, 'T' is tall, and 't' is dwarf) and a recessive plant with white flowers and dwarf height (rrtt), a Punnett square can be utilized to predict the offspring's genotypes. In the case of height, the plant that is tall and heterozygous (Tt) will have one allele for tall height (T) and one for dwarf (t), while the plant that is dwarf has two recessive alleles (tt). When these are crossed, the resulting genotypes of the offspring will be:

• Tt (tall)
• tt (dwarf)
• Tt (tall)
• tt (dwarf)

As we can see, two out of four or 50% of the offspring exhibit the dwarf phenotype. Hence, the correct answer to the question is (c) 50%.