Question

in the 1800s gregor mendel crossed pea plants that had purple flowers with pea plants that had white flowers. he had expected to see a mixture of colors in the offspring but instead all the offspring had purple flowers. which current understanding of the patterns of inheritance is best supported by mendels observations?
a. the two alleles of a gene are fully expressed in a heterozygote.

b. a mutated gene in a somatic cell cannot pass the trait to offspring.

c. genes located on the sex chromosomes show sex - linked inheritance.

d. some genes are expressed as either dominant or recessive in offspring.

Explanation:

• Option A: In a heterozygote, usually one allele is dominant (expressed) and the other recessive (not fully expressed in phenotype), so this is incorrect.
• Option B: The question is about flower color inheritance in pea plants, not about somatic mutations, so this is irrelevant.
• Option C: Pea plants do not have sex - linked inheritance related to flower color as they have no sex chromosomes in the context of this trait, so this is incorrect.
• Option D: Mendel's observation of all purple - flowered offspring when crossing purple and white - flowered plants shows that the purple flower allele (gene) is dominant and the white is recessive, meaning some genes are expressed as dominant or recessive in offspring.

Answer:

D. Some genes are expressed as either dominant or recessive in offspring.