NAME ______________________                                 PHYSIOLOGICAL ECOLOGY BIO 567

Code name ___________________                                 EXAM I                                 Spring 2000

1. Provide definitions for the following terms that include their significance to physiological ecology. (20 points)

"C3" photosynthesis


"C4" photosynthesis


water use efficiency


turgor pressure




preferred temperature








freeze tolerance

2. Whether or not it was described formally, you should be able to deduce what the "photosynthesis/transpiration compromise" refers to (especially if you read the article "Plant Water Balance" by Schulze et al. and "Photosynthesis" by Moony and Ehlringer) Therefore, explain what is meant by the "photosynthesis/transpiration compromise"? (5 points)




3. Locomotion is an energetic cost that animal must include in their energy budget. What other factors must be included? When this locomotor cost is expresses as the calories required to move a certain mass of animal a certain distance, this is referred to as the Acost of transport@. Based on the graph below, what form of locomotion seems to be the most efficient? Speculate as to why this might be so. (10 points)




4. What is the predicted relationship between dry matter production (expressed as net primary productivity) and precipitation for Oak trees in Ozark forests? Is this relationship the same for oak trees that grow in valleys and Oak trees that grow on ridge tops? (Hint: a well-labeled graph with a descriptive figure legend would be very useful for answering this question) (10 points)




5. What is the average transpiration ratio for a C3 and C4 plant, respectively? Explain why they are different? Is the C4 or C3 plant more water use efficient? (10 points)




6. a. List the pathways of heat loss and heat gain for an endotherm in a cold environment (5 points).














b. Discuss the major thermoregulatory advancements between reptiles and birds/mammals. Why are these such an improvement? (5 points)




7. Can a plant grow in a 1.0 molal sucrose solution? Explain. (5 points)




8. Suppose root cortex cells have an osmotic potential of -1.8 MPa and turgor pressure of 0.3 MPa, and the soil water potential is -1.5 MPa. Which way will water move? Explain (hint: show your work) (5 points).



9. You are "in charge" of the evolution of a new desert-adapted plant/animal (chose one). It can utilize water conservation mechanisms found in other plants/animals, or you can design unique ones. Describe below the specific water conservation mechanisms (behavioral, anatomical, biochemical, physiological) that your plant/animal will possess. (10 points)




10. a. What are the primary osmotic problems faced by marine vertebrates? What osmotic problems are faced by freshwater vertebrates? (5 points)




b. Select 3 groups of vertebrates that can occur in both habitats, and briefly describe how they solve these problems. (10 points)

































Extra credit: (you may choose to answer one of the following - A or B)

A. In the article "Integrated Responses of Plants to Stress: A centralized system of physiological responses", the author (Chapin) suggests that all plants respond to stress of many types in basically the same way. Whether or not you read the article or remember it, you should be able to answer the following questions (10 points):

a. Give a list of environmental stresses (perturbations) that plants encounter almost daily (e.g., what makes most environments sub-optimal)?

b. List the suite of plant traits that characterize plants from low resource environments (e.g., deserts, tundra, shaded understory, infertile soils)

                            c. Describe some physiological responses to stress?

d. Can you guess (or remember) the centralized system that supposedly responds to stress in all plants?


B. A common graph in all plant physiology, plant physiological ecology, horticulture, and plant ecology texts is a graph of soil, root and leaf water potential in a soil that is drying. I did not show an example of this graph. However, based on what you know about water potential in the soil and plant, movement of water from the soil through the plant to the atmosphere, and the status of stomates at night in C3 plants, address the following (10 points):

Graph soil, root, and leaf water potentials over a 6-day drying cycle (i.e. soil at field capacity (-0.3 MPa) to soil at the wilting point (-1.5MPa). Make sure you show the diurnal course (i.e., day/night cycle). (Hint: the x-axis will have 12 tick marks (day and night over 6 days), and y-axis will be water potential in MPa; the figure will have 3 lines for soil, root and leaf water potential, with soil water potential declining from -0.3 to -1.5 MPa without any diurnal pattern)