Stomata: Pre-lab work
Instruction:
Read through the information on transpiration and stomata in the book. Most of the information on will be
new and will be needed to answer some of the questions below. More research will have to be done to
answer the remaining questions. As a group, complete the answers below and submit the work to this folder.
1. Plants are made up of eukaryotic cells. What are some of the features of a eukaryotic plant cell, when
compared to a prokaryotic one?
2. Plants carry out photosynthesis. Summarize the two stages of photosynthesis which you have learned
about, including specific locations, substrates used and main products of the reactions.
3. Photosynthesis is a biochemical process which relies on the combined and synergetic work of many
enzymes and metabolic pathways which are sensitive to environmental changes. List the factors affecting
photosynthesis:
4. During photosynthesis and cellular respiration gases such as CO2, O2 and H2O need to be exchanged
between the inside of a leaf and the outside of the leaf. Which structures of a leaf’s upper and lower side
allow for these gaseous molecules to diffuse ?
5. Describe the function of the structure mentioned above and label all parts of the diagram below:
6. Stomata are particularly useful for gas exchange because they can be opened and closed by the plant.
Using scientific language and reference to keywords like osmosis, active transport, energy, ions, abscisic
acid, turgid, flaccid, explain how plants do this. Use
https://en.m.wikipedia.org/wiki/Stoma for more information.
7. Explain how an increase in Carbon dioxide concentration affects photosynthesis and, as a consequence, the
opening and closing of stomata:
8. Explain how a change in light intensity affects photosynthesis and, as a consequence, the opening and
closing of stomata:
9. The density of stomata is the total number of stomata in a known area of vision. You can calculate this
using the formula area = πr2, when you have measured the true radius of the field of view (r) under the
microscope – something which can easily be done using a tiny ruler - and counted the number of stomata
seen. Why is information about the stomatal density important for plant ecology?
10. Some cacti thrive in some of the hottest deserts on earth where water is extremely scarce for most of the
year. To deal with the scarcity of water, cacti have evolved an unusual set of adaptations including a
remarkable capacity to soak up water into fleshy stems when it rains and hold onto this water during
drought. One way cacti have to hold onto water is to ONLY open their stomata at night when it is cooler
and more humid. However, if CO2 is only allowed into these plants at night how are cacti able to synthesize
sugar with it via photosynthesis during the day many hours later?
11. Why might it be adaptive for stomata to occur mostly (if not entirely) on the undersides of leaves? What
plants show the reverse pattern for which stomata are only on the upper leaf surface?
12. Scientists seem to have discovered a relationship between the genome size of a plant and its stomatal
density. Describe the relationship and discuss its importance in ecology. This article will give a bit more
insight.