Biology - HOT Science Lab

Student
7. Scan the slide until you find a good area where you can see the stomata. Each stoma is
bordered by two sausage-shaped cells that are usually smaller than surrounding
epidermal cells. These small cells are called guard cells and, unlike other cells in the
epidermis, contain chloroplasts.
8. Cut a small piece of the Oyster plant leaf. Observe directly under the microscope. A cross
section or slide is not needed. Observe the stomata and guard cells and compare them to
the ones previously observed.
Analysis:
1. Sketch and label the Stoma, Guard Cells, Epidermal Cells, and Chloroplasts
2. Estimate the number of stomata in both of your samples.
3. Where were most of the stomata found Why do you think this is Explain your answer in
evolutionary terms.
Extension:
1. Question: Will plants have more stoma open during the day than during the night
2. Develop a hypothesis about the number of open stomata found in a plant kept in the dark
compared to a plant in the light.
3. Repeat the procedure above for preparing your slide. You will make two impressions, one
from a "Dark Plant" and one from a "Light Plant" You will compare the two impressions.
4. Write a short paragraph that answers the question; use your data to support your
conclusions.
5. Discuss the factors that cause the stomata to be open during the day and closed at night.
Under what circumstances the stomata might be closed during the day
Biology HSL Page 110
Curriculum and Instruction