Question

what is the probability that offspring w will have the dark hair phenotype?
a. 25%
b. 50%
c. 75%
d. 100%

Explanation:

Step1: Analyze the cross

The cross involves parents with dark - haired and light - haired phenotypes. Assuming simple Mendelian inheritance and dark hair is a dominant trait (D) and light hair is a recessive trait (d). The dark - haired parent is likely heterozygous (Dd) if it can produce light - haired offspring in other crosses shown. The light - haired parent is dd.

Step2: Set up Punnett square

The cross is Dd x dd. The possible gametes from Dd are D and d, and from dd are d and d. The Punnett square has two columns (D and d from Dd) and two rows (d and d from dd). The offspring genotypes are Dd and dd in a 1:1 ratio.

Step3: Determine phenotype probability

Since Dd shows the dark - hair phenotype and dd shows the light - hair phenotype, the probability of having a dark - hair phenotype (Dd) is 50%.

Answer:

B. 50%