Review:Plant-like Protists
(ALGAE pages 510-516)
1. List the reasons why euglenoids
should be classified as protozoans
and also as algae
2. In what ways do the sporophyte and
gametophyte generation of an alga
differ from each other?
3. Phycobilins, pigments that absord
green, violet and blue light, are an
important part of red algae. Explain
why.
C. Fungus-like Protists
Most of these protists are small and
live in damp or watery places, helping
to break down dead organic matter.
Divided into three groups:
Plasmodial Slime Molds
Cellular Slime Molds
Water Molds
Answers to Review Q’s
1. Euglenoids are algae-like in that they
contain chloroplasts, whereas they are
protozoan-like in their locomotion
(flagellum).
2. Haploid gametophytes form gametes
and diploid sporophytes form spores.
3. Phycobilins can absorb the green,
violet, and blue light that penetrates
deep water.
1. Plasmodial Slime Molds
Alternate between an emoeboid form and a
spore-producing fruiting body
When feeding, they form a mass of
cytoplasm called a PLASMODIUM
If the slime mold cannot find enough food, it
will stop feeding and fomr a fruiting body that
produces spores. These spores can spread
by wind or animals and they remain dormant
until conditions become favourable
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A slime mold (Physarum polycephalum),
showing a creeping mass of yellowish
protoplasm called a plasmodium.
Sporangia of Plasmodial Slime Mold
Fuligo Septica
aka: Scrambled Egg Slime
White Coral Slime Mold
This bright yellow slime mold is feeding in these two
slides. The top left photo shows it moving in an upward
direction.
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JUST FOR FUN
In the spore bearing stage, Fuligo septica forms an
aethelium. In this stage, the slime mold is very dry and
brittle. Breaking it open exposes millions of dry, dusty
spores.
2. Cellular Slime Molds
Move about as single,
unattached amoebas for
most of their lives, until
a chemical, produced by
one of them, signals that
the single life is over.
Slime molds reproduce by sending out spores, yet their bodies
are continually pulsating, allowing them to actually travel
through the forest in search of food. Slime molds are
continually circulating their cellular material, creating the
pulsations which control their movement. But the pulsations
are not constant--they may decrease or accelerate depending
on what the Slime mold encounters along its path. In the
course of his experiments, Dr. Laane made some interesting
discoveries about the Slime mold's tastes. Exposed to
cigarette smoke, the pulsations sped up. Given its first stiff
drink, the Slime Mold's pulsations also increased, but not for
long. Eventually, not even the Slime mold could avoid a hangover and its pulsations slowed to a temporary stand-still.
Then, one by one, up to 100,000
amoeba in an area will find each other
and fuse into a single, multicellular
body called a PSEUDOPLASMODIUM:
like a plasmodium, but each individual
cell remains a separate unit.
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The Pseudoplasmodium forms a fruiting
body in order to reproduce spores.
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Wonderful slime mold website
A composite photograph of the
Dictyostelium discoideum life cycle.
3. Water Molds
Decomposers or parasites
Typically grow in fresh water on
decaying plants and animals
Example: Plasmopara viticol is a water
mold that almost wiped out France’s
vineyards
Plasmopara viticol
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Review: Fungus-like Protists
(SLIME MOLDS pages 517-521)
1. Describe the protozoan and funguslike
characteristics of slime molds.
2. How could a water mold eventually kill
a fish?
3. How does a plasmodial slime mold
differ from a cellular slime mold?
4. In what kinds of environments would
you expect to find slime molds? Why?
Answers to Review Q’s
1. They are protozoan-like in that at
different stages they have flagella dn
the ability to move like amoebas.
They are fungus-like in that they
produce spores and many are
saprophytic decomposers.
2. The mold digests the tissues
3. A plasmodial slime mold feeds as a
multinucleated plasmodium, but
cellular slime molds feed as amoeboid
cells.
4. Slime molds should live in warm, moist
environments where moisture prevent
dehydration and provide the conditions
their food supply needs to thrive.
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