Answers to Concept Checks

• 1. d
• 2. No, because horses are expensive to house, feed, and propagate, they have too few progeny, and their generation time is too long.
• 3. Developments in cytology in the 1800s led to the identification of parts of the cell, including the cell nucleus and chromosomes. The cell theory focused the attention of biologists on the cell, eventually leading to the conclusion that the nucleus contains the hereditary information.