Chapter 7 Notes
Protists and Fungi
7-1 Notes: Protists
Q: What is a protist?
A: Protists are eukaryotes that live in moist environments.
Protists are very diverse:
•Most are unicellular, but some are multicellular.
•Some are heterotrophs, some are autotrophs, some are both
•Some protists can move, some cannot.
Q: How are protists grouped?
A: Three main categoies of protists are:
1) animal-like protists (also called protozoans)
2) fungus-like protists
3) plant-like protists (also called algae)
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Animal-like Protists (Protozoans)
Q: Why are these protists “animal-like”
A: Like animals, protozoans are heterotrophs that must obtain
their own food, and most of them can move from place to
place to get it.
However, protozoans are different from animals because they
are unicellular and animals are multicellular.
Scientists group protozoans based on how they move and
live:
1) Sarcodines
2) Ciliates
3) Zooflagellates
4) Sporozoans
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1) Sarcodines- protozoans with pseudopods- a “foot” of
cytoplasm used for locomotion and feeding; sarcodines
also have contractile vacuoles- collects excess water
and expels it from the cell.
example: ameba
2) Ciliates- protozoans with cilia- hairlike projections used
in locomotion, feeding, and sensing their environment.
example: paramecium
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3) Zooflagellates- protozoans with flagella to move, and
live in symbiosis- a relationship between two
organisms living closely where at least one benefits.
When both organisms benefit it is called mutualism;
example: Giardia
4) Sporozoans- protozoans that are parasites and feed
on the cells and fluids of their host, sometimes more
than one host; example: Plasmodium- causes malaria
Fungus-Like Protists
Q: How are fungus-like protists similar to fungus?
A: Fungus-like protists are similar to fungus because they
are heterotrophs, have cell walls, and use spores to
reproduce.
However, they are different from real fungus because they
are able to move at some point during their life.
There are three different types of fungus-like protists:
1) Water Molds
2) Downy Mildews
3) Slime Molds
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1) Water Molds- live in water or moist places, grow as
tiny threads of “fuzz,” can attack food crops such as the
one that caused the potato famine in Ireland in the
1800’s.
2) Downy Mildew- Same characteristics as water molds.
3) Slime Molds- Live in moist soils and on decaying plants
and trees, they move like amebas with psuedopods, can
creep together to form multicellular masses and
release spores to produce new generations.
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Plant-Like Protists (Algae)
Q: What is the one characteristic that plants and all algae share?
A: All plants and algae are autotrophs- they can make their own food
using sunlight.
However algae are also varied in how they live and what they look
like.
Some algae are unicellular, some form colonies, and some are
multicellular.
•Unicellular algae carry out all the functions necessary for life.
•Colonial algae are still unicellular algae that just live together.
Therefore each cell still carries out all the necessary life functions.
•Multicellular algae contains specialized cells that perform certain
tasks.
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Types of Plant-like Protists or Algae:
Unicellular
1) Euglenoids- green, unicellular algae, found in freshwater. They have
one animal-like characteristic: they can be heterotrophs under
certain conditions (like when sunlight is not available)
2) Dinoflagellates- Unicellular algae covered by thick plates that look
like a suit of armor and exist in a variety of colors. Some glow in
the dark and all have two flagella.
3) Diatoms- Have glasslike cell walls, live in fresh or salt water, and are
a food source for heterotrophs. When they die, they collect and
form an abrasive substance that make a good polishing cleaner.
Multicellular
1) Green Algae
2) Red Algae
3) Brown Algae
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7-2 Notes: Algal Blooms
Q: What is a red tide?
A: A red tide is a salt water algal bloom.
Q: Why is it “red?”
A: Because many algae that rapidly grow often contain red
pigments and turn the water red.
Q: What causes them?
A: When there is an increase of nutrients in the water there is
a rise in the algae that eat these nutrients.
Q: Are they dangerous?
A:Yes, because algae produces toxins and when there is an
increase in algae, there is an increase in the toxins they
produce and those toxins get concentrated in the bodies of
the organisms that eat the algae and can kill them.
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Q: What is it called when an algal bloom happens in
freshwater?
A: It is called eutrophication.
Q: Why does this happen?
A: Same reason as salt water….increase in nutrients.
Q: Is it a bad thing?
A: Yes. The rapid growth of algae in a pond or lake triggers a
series of events with serious consequences:
1) The layer of algae prevents sunlight getting through to
other water plants.
2) Those organisms die and sink to the bottom.
3) Bacteria break them down and reproduce rapidly.
4) Bacteria use up available oxygen and fish die.
5) Only the algae survives .
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LIFE SCIENCE PRIORITY LIST:
1)Pg. 230 #1-4 - Due Today
2) 7-2 Worksheet- Due when you
walk in tomorrow (but can go in
the tray today)
3) Vocabulary
7-3 Notes: Fungi
What are fungi?
Fungi vary in size from unicellular yeast to multicellular
mushrooms.
Most fungi share three important characteristics:
1) They are eukaryotes
2) They use spores to reproduce
3) They are heterotrophs that absorb their food.
The cells of fungi are arranged in hyphae- threadlike tubes
that make up the bodies of multicellular fungi.
The appearance of fungi depend on how the hyphae are
arranged. Example: loose hyphae= fuzzy molds; tighly
packed hyphae= solid mushroom caps
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Q: What do fungi have in common with plants?
A: They have cell walls
Plant cell walls are made of cellulose.
Fungi cells walls are made of chitin.
Q: What do fungi have in common with animals?
A: They are heterotrophs- they must obtain their food from an
outside source.
How do Fungi obtain their food then?
Step 1- Fungi grows hyphae into the food source
Step 2- Digestive chemicals ooze from the hyphae into the food.
Step 3- The digestive chemicals break down the food into
substances that can be absorbed by the hyphae.
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Some fungus, like the one that causes athletes foot are
parasites that break down chemicals of living
organisms.
Other fungus feed on the remains of dead organisms.
Q: How do fungi reproduce?
A: Fungi usually reproduce by producing lightweight
spores that are surrounded by a protective covering.
The spores are then carried by wind or water to
grow new fungi.
Spores are produced in fruiting bodies- the
reproductive hyphae that grow out of a fungus (the
part of the fungus you can see)
The Two types of reproduction in fungi:
1) Asexual- Type of reproduction used when there is
adequate moisture and food.
Unicellular yeast undergo a reproduction process
called budding (which is asexual) where no spores are
produced. Instead, a small yeast forms from a large
yeast cell and just breaks away to live on its own.
2) Sexual- Type of reproduction used when the
conditions become unfavorable:
hyphae of two different fungi grow together- exchange genetic
information- new spore producing structure forms- spores
develop into a new fungi
Q: Which form of reproduction will produce an offspring that
is different from the parent? Asexual or sexual?
A: Sexual because there is an exchange of genetic information.
Classification of Fungi- based on the shape of their sporeproducing structures:
1) Threadlike Fungi- common molds
2) Sac Fungi- yeast, morels, truffels
3) Club Fungi- bracket fungi, puffballs
4) Imperfect Fungi- penicillum
Fungus and the Living World
1) Fungi help in Environmental recycling by being
decomposers. Decomposers return important nutrients to
the soil.
2) Fungi are a source of food like bread made from yeast, they
help in making some cheeses, and edible mushrooms.
3) Fungi can cause disease in crops and in humans like athletes
foot and ringworm.
4) Fungi can help fight disease because penicillum is made
from mold which is a fungus.
5) Fungi help plants grow larger in a symbiotic mutualism
relationship because the fungus helps the plant absorb food
and nutrients and the plant give the fungus some extra
stored food to absorb. This is called fungus-plant root
association.
Lichen- A lichen is a fungus and an algae that live
together in a mutualistic relationship.
The fungus gets- food from the autotrophic algae
The algae gets- water and minerals from the fungus
Lichens are “pioneer organisms” because they are the
first organisms to appear on the bare rocks after a
disaster.