Butterflies

Exercise 31 Answers to Questions

1. a. How do taproot and fibrous root systems help plants survive and reproduce?

b. Would one type of root system provide an adaptive advantage in a particular environment such as a rain forest? tap--more volume

2. a. In the space below, sketch the root tips that you examined. In which root tip are cells largest? In which area are they smallest?

b. Aside from their size, do all cells in the root tip appear similar? Why is this significant? No, because different cells have different functions; however, the meristem cells should all appear similar.

3. a. Why do you think root hairs occur only in the zone of maturation? so they won't get sheared off as root grows through the soil

b. What is the function of root hairs? absorption

4. a. Based on the presence of amyloplasts, what do you suppose is the primary function of the cortex? storage of starch

b. Do secondary roots arise inside the primary root or on its surface? from inside

c. How does the structure of a monocot root differ from that of a dicot?

Dicot roots have a central stele surrounded by a thick cortex and epidermis. Monocot roots have a vascular cylinder of xylem and phloem that surrounds a central pith.

5. a. Where is the starch located in carrot root? cortex

b. What can you conclude from this observation? cortex functions in energy storage

6. a. How does the absence of a cap at a shoot apex differ from the apical meristem of a root? root has cap

b. How would you explain this difference? shoot is not moving through soil, so there is no need for a similar structure

c. Are all cells in the shoot apex the same size? Why is this significant? No, because different cells have different functions; however, the meristem cells should all appear similar.

d. How does the variation in cell size compare with that of roots? similar

7. a. What is the significance of a coating of cutin on the epidermis?

prevents desiccation

b. How does the arrangement of xylem and phloem in stems differ from that of roots? in shoots, xylem is opposite phloem; xylem and phloem alternate in roots

8. How does the arrangement of vascular bundles differ in stems of monocots as compared to dicots? monocots--vascular bundles arranged "randomly"; dicots--vascular bundles in ring

9. How is secondary growth different from primary growth? primary meristem produces growth in length, not girth

10. a. How do you account for seasonal production of different-sized cells? water availability

b. What is the common name for secondary xylem? wood

c. What is "grain" in wood? layers of xylem

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