Leaves and Photosynthesis
Goals and Objectives:
-
Be able to describe the three major themes
that have been involved in the evolution of plant leaves.
-
Be able to explain how a plant leaf handles
the dual problems of obtaining carbon dioxide for photosynthesis while
maintaining a sufficient water balance.
-
Be able to diagram and label the structures
in a cross section of a dicot and monocot leaf.
-
Be able to explain the structure/function
relationship in a plant leaf.
-
Be able to explain how stomata are able to
increase carbon dioxide intake, and water loss.
-
Be able to describe the mechanisms involved
in stomatal opening and closing.
-
Be able to analyze the interplay between several
environmental conditions that would affect stomatal opening and closing.
Study Questions:
-
What are the three evolutionary modifications
that we see in plants that have allowed plants to become efficient at absorbing
light energy while conserving water? (pages 143-144)
-
With these three evolutionary modifications
in mind, how do plant structures and physiology in algae and
bryophyts deal with these three aspects of photosynthesis? (pages 144-146)
-
With these three evolutionary modifications
in mind, how do higher plant structures and physiology deal
with these three aspects of photosynthesis? (page 147)
-
How are the internal structures of a plant
leaf constructed so as to absorb the maximum amount of light? (pages 147-148)
-
How are the structures of a plant leaf designed
to facilitate absorption of carbon dioxide? (pages 148-150)
-
Why do small pores (like stomata) increase
diffusion? Relate this idea to the diffusion of water vapor and carbon
dioxide into and out of the leaf by way of the stomata. (page 152)
-
Describe how the structure of the guard cells
allows the opening of the stomatal apparatus. (page 152)
-
Describe how the physiology within the guard
cells allows the opening of the stomatal apparatus. (page 153-154)
-
The study of stomatal opening and closing
has been difficult. Mainly because so many environmental factors
impinge on the functioning of the guard cells. Describe how each
of the following would affect the opening and closing of the stomatal apparatus:
(pages 154-157)
-
CO2 levels inside and outside the
leaf.
-
Light
-
Water status of the leaf
-
Temperature of the leaf
-
Wind
-
Circadian rhythms