Name _______________________ Period _____ Date ___________________
EXAMINING THREE FORMS OF FUNGI
Background Information
For everyday purposes, fungi may be organized into three categories
according to their basic form: mushrooms, yeasts, and molds. Mushrooms
are shaped like umbrellas. Yeasts consist of single cells. Molds are fuzzy,
shapeless, fairly flat fungi. Although these three categories are quite handy, they
are not used in the formal classification of fungi because they do not reflect the
evolutionary relationships among fungi. In this investigation you will observe and
compare the structures of yeast, a mushroom, and a mold.
Problem
How are yeasts, mushrooms, and molds similar? How are they different?
Materials (per group)
Yeast culture-mix with warm water and sugar
Mushroom
Bread mold culture
Medicine dropper
4 glass microscope slides
4 coverslips
Hand lens
Microscope
Forceps
Procedure
Part A: Yeast
(yeast mixture)
1. Look closely at the yeast culture. Smell it cautiously by gently waving your
hand over the culture and directing the fumes toward your nose. CAUTION:
Never inhale fumes directly from a container. Record your observations in the
data table.
2. Examine the yeast culture with the unaided eye. Record your observations in
the data table.
(yeast slide)
3. Using a medicine dropper, place a drop of the yeast culture on a glass slide
and cover it with a coverslip.
4. Examine the yeast under the microscope. Try to locate some yeast cells
budding (reproducing). Make a drawing of what you observe on page 3.
Label the yeast cells in your drawing. Record written observations in the
data table on page 4.
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Part B: Mushroom
(whole mushroom)
5. Examine a whole mushroom with the unaided eye. Record your written
observations in the data table.
(stalk slide)
6. With the medicine dropper, place a drop of water in the center of a glass
slide.
7. With the forceps, carefully peel off a thin layer of the mushroom's stalk.
8. Place the thin layer of mushroom stalk in the water on the glass slide. Using
the forceps, remove any folds or creases. Cover the layer with a coverslip.
9. Observe the mushroom stalk under the microscope. Notice the arrangement
of the hyphae. Make a drawing of what you observe on page 3. Label the
hyphae in your drawing. Record written observations in the data table on
page 4.
(gill slide)
10. Again using the medicine dropper, place a drop of water in the center of a
glass slide.
11. With the forceps, carefully remove a piece of one of the mushroom's gills.
12. Place the gill in the water on the glass slide. Using the forceps, remove any
folds or creases. Cover the gill with a coverslip.
13. Observe the gill under the microscope. Look for reproductive spores. Make
a drawing of what you observe on page 3. Label the spores in your
drawing. Record written observations in the data table on page 4.
Part C: Mold
(mold)
14. Examine the bread mold with the unaided eye. CAUTION: Do not try to
smell the bread mold. Some people are allergic to mold spores. Record
your observations in the data table.
(mold slide)
15. Again using the medicine dropper, place a drop of water in the center of a
slide.
16. Using the forceps, remove a tiny bit of the bread mold. Place the sample of
bread mold in the water on the glass slide. Cover it with a coverslip.
17. Observe the bread mold under the microscope. Try to locate strands of
hyphae with sporangia (spore cases) on the ends. Make a drawing of what
you observe and record your observations in the data table. Label the
hyphae and sporangia (spore cases) in your drawing.
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NAME ____________________________________
YEAST UNDER MICROSCOPE (LOW OR HIGH POWER)
(draw & label yeast cells)
MUSHROOM UNDER MICROSCOPE (LOW OR HIGH POWER)
STALK
(draw & label hyphae)
GILL
(label spores)
MOLD UNDER MICROSCOPE (LOW OR HIGH POWER)
(draw & label hyphae and sporangia)
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Observations
DATA TABLE
Written Observations
Fungus
Unaided Eye
Microscope (10X or 40X)
Smell:
Yeast
Look:
Stalk:
Mushroom
Gill:
Mold
1. Describe how the hyphae are arranged in the mushroom stalk. ___________
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2. Describe how hyphae are arranged in the bread mold. __________________
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3. In which kinds of fungi did you observe spores? Where were these spores
found? _______________________________________________________
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4. How do yeast cells reproduce? Did you see any signs of reproduction in the
yeast cells? __________________________________________________
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Analysis and Conclusions
1. Explain why the hyphae are arranged differently in the bread mold and in the
mushroom stalk?
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2. Now that you’ve learned how yeasts & molds reproduce, which do you think
would reproduce more rapidly, yeasts or molds? Explain your answer.
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Critical Thinking and Application
1. Why is it an advantage for molds and mushrooms to produce many spores?
(Hint: Think about the first step of natural selection – Overproduction)
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2. Some people think that beer (which includes alcohol) "smells funny." What is
a possible reason for this? (Hint: Think about what we smelled in the lab.)
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3. In the autumn, when dead leaves pile up, some people have "allergy attacks",
especially if it has been rainy. What do you think might be the cause of the
allergies? Explain. ______________________________________________
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