Question

A plant has dominant and recessive traits for flower color. The dominant color is amethyst (a), and the recessive trait is white (a). Which punnett square correctly shows two homozygous parents producing heterogeneous offspring?

1) a
2) b
3) c
4) d
5) e

Answer 1

Option b correctly shows two homozygous parents producing heterogeneous offspring with a 50% chance of amethyst color and a 50% chance of white color.

Step-by-step explanation:

A Punnett square is used to predict the possible genotypes and phenotypes of offspring in a cross between two parents. In this case, we have two homozygous parents, which means they have the same alleles for flower color. A Punnett square shows all the possible combinations of alleles for the offspring, with each parent contributing one allele.

From the given Punnett squares, option b correctly shows two homozygous parents producing heterogeneous (heterozygous) offspring. The Punnett square shows that there is a 50% chance of having offspring with the dominant amethyst color (Aa) and a 50% chance of having offspring with the recessive white color (aa).

Answer 2

The question seems to have an inconsistency in the lettering of the dominant and recessive alleles, but based on standard convention, a Punnett square for two homozygous parents (one with AA and one with aa) would result in 100% Aa heterozygous offspring, all displaying the dominant phenotype.

Step-by-step explanation:

No option is given that shows two homozygous parents producing heterozygous offspring. However, to set up a correct Punnett square for two homozygous parents, with dominant amethyst (A) and recessive white (a), you will place AA on one side for the homozygous dominant parent and aa on the other side for the homozygous recessive parent. The resulting offspring would all be heterozygous (Aa).

In classical Mendelian genetics, when two homozygous organisms with different alleles are crossed (AA x aa), the result is 100% heterozygous (Aa) offspring. This occurs because each parent can only contribute one type of allele to their gametes—dominant (A) from the homozygous dominant parent and recessive (a) from the homozygous recessive parent. When these gametes combine during fertilization, the resulting offspring are all Aa, displaying the dominant phenotype. Do note, since the question mentions the symbols 'a' and 'a' for dominant and recessive traits, respectively, ensure consistent symbol usage when solving. It is crucial to maintain the convention of using uppercase for dominant alleles and lowercase for recessive alleles, which implies that 'A' should represent the dominant amethyst and 'a' the recessive white trait in a conventional Punnett square.