What is the probability that a plant from a monohybrid cross of heterozygous parents, is homozygous dominant OR homozygous recessive?

• A. ½.
• B. ¼.
• C. ¾.
• D. 1.

Answer: (A)

Verified step by step guidance

1. Identify the genotypes of the parents in the monohybrid cross. Since both parents are heterozygous, their genotype is represented as 'Aa', where 'A' is the dominant allele and 'a' is the recessive allele.
2. Set up a Punnett square to visualize the possible genotypes of the offspring. Place one parent's alleles on the top and the other parent's alleles on the side of the square.
3. Fill in the Punnett square by combining the alleles from each parent. This will result in four possible genotypes for the offspring: 'AA', 'Aa', 'Aa', and 'aa'.
4. Determine the probability of each genotype. 'AA' and 'aa' are homozygous genotypes. Count the number of 'AA' and 'aa' combinations in the Punnett square.
5. Calculate the probability of the offspring being homozygous dominant ('AA') or homozygous recessive ('aa'). Add the probabilities of these two genotypes to find the total probability of the offspring being either homozygous dominant or homozygous recessive.