Biology 304

Study Guide for Exam 2

Chapter 29

From Table 29-2 (p 648), know the functions (not symptoms) for each of the micro- and macro nutrients.

What role do each of the following play in the nitrogen cycle? nitrogen fixation, nitrification, denitrification, and ammonification (see Fig. 29-8, p 654)). Why does planting legumes improve the cultivation of all crops?

Chapter 30

How do water potential changes and cell wall structure play a role in stomatal opening and closing? (pp 668-670; also pp 619-621 in Chap. 27)

Explain the cohesion-tension theory for water movement in the xylem including the role of water potential gradients, the physical properties of water (i.e., polarity), and anatomical features of tracheary elements (e.g., bordered pits, thick secondary walls, lack of cytoplasm).

How do humidity and air currents affect transpiration?

What are embolisms and why are they significant? (p 673)

Distinguish between apoplastic, symplastic, and transcellular movement of water

( Fig. 30-14, p 676). What is the significance of the Casparian strip in terms of apoplastic movement of water?

What is root pressure and when is it generated?

Discuss the pressure-flow hypothesis of assimilate movement in the phloem (pp680-685) including the role of water potential, pressure gradients, phloem loading and unloading, proton pumps and sucrose-proton cotransport.

Chapter 27

Using Table 27-1 (p 604) as a guide, be able to distinguish between the 5 major groups of plant hormones on the basis of their chemical structure, site of synthesis, mode of transport, and physiological effects. Use my lectures as an indicator of what topics to emphasize.

Molecular basis of hormonal action: What are two hypotheses for explaining how hormones regulate cell expansion? (Fig. 27-20, p 618). How do hormones regulate gene expression? (handout and Fig. 27-22, p 619)