Topic 3.2 Check and Reflect
Key Concept Review
1. Describe a type of cell division that occurs during the asexual reproduction of a unicellular organism.
2. What type of cell division is required for sexual reproduction? How does it differ from cell division during asexual reproduction?
3. Describe the type of cell division that occurs in the body cells of multicellular organisms.
Connect Your Understanding
4. Using diagrams, explain what happens to the DNA during cell division to produce sex cells (gametes).
5. When a cell divides during asexual reproduction, it divides its cell contents between the two resulting cells. Describe what happens to the DNA of the cell during this type of cell division. Explain how this process ensures that the same characteristics are passed from generation to generation.
6. Why does sexual reproduction produce offspring with characteristics that are different from their parents, whereas offspring produced through asexual reproduction are identical to their parents?
Extend Your Understanding
7. If the amount of DNA in a gamete of an organism is n, is the amount of DNA in the body cells of that organism equal to one halfn, n, or 2n? Explain.
8. Which form of cell division—binary fission or meiosis—poses the lower risk for the transmission of genetic disorders? Support your answer.
Topic 3.3 Check and Reflect
1. Explain how dominant and recessive traits differ from each other.
2. How does a purebred individual differ from a hybrid individual?
3. List examples of dominance, recessiveness, and incomplete dominance. Use a different example for each from those given in the text. Connect Your Understanding
4. How could two black cats produce a kitten that has white fur? Use a diagram to explain your answer.
5. If you wanted to be certain that a trait would appear in the offspring of the plants or animals that you were breeding, what would you have to find out about the parents? Explain your answer. 6. Suppose a new flower in your garden displays an intermediate colour. For example, you begin to see orange flowers although you originally planted only red and yellow flowers. What pattern of inheritance would you be observing in this situation? Explain your answer.
7. Can dominance or recessiveness explain why two cats from the same litter may be different masses or have different leg lengths? Explain your answer.