Which of the following statements accurately describes both pleiotropy and polygenic inheritance?

• A. Both involve a single gene affecting multiple traits.
• B. Both involve the interaction of genes that can affect the expression of multiple phenotypes.
• C. Both are examples of Mendel's law of independent assortment without exception.
• D. Both involve multiple genes influencing a single trait.

Answer: (B)

Verified step by step guidance

1. Step 1: Define pleiotropy and polygenic inheritance to understand their characteristics. Pleiotropy occurs when a single gene influences multiple phenotypic traits, while polygenic inheritance involves multiple genes contributing to a single trait.
2. Step 2: Analyze the first statement: 'Both involve a single gene affecting multiple traits.' This accurately describes pleiotropy but not polygenic inheritance, which involves multiple genes, so this statement is only partially correct.
3. Step 3: Examine the second statement: 'Both involve the interaction of genes that can affect the expression of multiple phenotypes.' Consider that pleiotropy involves one gene affecting multiple traits, and polygenic inheritance involves multiple genes affecting one trait. This statement suggests gene interactions affecting phenotypes, so evaluate if it correctly applies to both.
4. Step 4: Review the third statement: 'Both are examples of Mendel's law of independent assortment without exception.' Recall that Mendel's law applies to genes on different chromosomes or far apart on the same chromosome, but pleiotropy and polygenic inheritance often involve linked or interacting genes, so this statement is likely incorrect.
5. Step 5: Consider the fourth statement: 'Both involve multiple genes influencing a single trait.' This describes polygenic inheritance but not pleiotropy, which involves a single gene affecting multiple traits, so this statement is only partially correct.