Refer to the Figures

question 67

Essay

Refer to the figures.
The two figures represent the results of studies on a mutualism between the plant Medicago and its partner, a mycorrhizal fungus. The top figure shows the percentage of carbohydrate transferred from the plant to the fungus, depending on the amount of phosphorus the fungus supplies to the plant. The bottom figure shows the amount of fungal phosphorus incorporated by plant roots, depending on the amount of carbohydrate supplied to the fungus. Given the information in these two figures, does the mutualism appear to be under the control of the plant or the fungus, or do both partners exercise some control?

---

Definitions:

Premolars

In mammals, teeth positioned between the canines and molars; adapted for crushing and grinding; compare with incisors, canines, and molars.

Incisors

Chisel-shaped teeth of a mammal; adapted for biting and cutting food. Compare with canines, premolars, and molars.

Digestive Tract

The series of hollow organs joined in a long, twisting tube from the mouth to the anus, where digestion and absorption of food occurs.

Rugae

Folds, such as those in the lining of the stomach.