Question

different cell types in the body
○ are identical except for their superficial appearance.
○ have the same genes, but different sets of genes are inactivated.
○ have the ability to take on the characteristics of each other or any cell in the body.
○ produce exactly the same proteins.
○ have different genes.

Explanation:

• Option 1: Different cell types have distinct functions and internal structures, not just superficial differences. Eliminate.
• Option 2: In the body, most cells (somatic cells) have the same genome. Cell differentiation occurs via gene regulation (inactivation/activation of different gene sets), leading to different cell types. This is correct.
• Option 3: Only stem cells (especially pluripotent ones) can differentiate into many cell types; most differentiated cells can't take on other cell's characteristics. Eliminate.
• Option 4: Different cell types produce different proteins based on their function (due to gene regulation), so they don't produce the same proteins. Eliminate.
• Option 5: Most body cells (except gametes) have the same genes (same genome). Eliminate.

Answer:

B. have the same genes, but different sets of genes are inactivated.