1) All protists are
A) unicellular.
B) eukaryotic.
C) symbionts.
D) monophyletic.
E) mixotrophic.
Answer: B
2) Biologists have long been aware that the defunct
kingdom Protista is polyphyletic. Which of these statements is most consistent
with this conclusion?
A) Many species within this kingdom were once classified
as monerans.
B) Animals, plants, and fungi arose from different
protist ancestors.
C) The eukaryotic condition has evolved more than once
among the protists.
D) Chloroplasts among various protists are similar to
those found in prokaryotes.
E) Some protists, all animals, and all fungi share a protist
common ancestor, but these protists, animals, and fungi are currently assigned
to three different kingdoms.
Answer: C
3) According to the endosymbiotic theory of the origin of
eukaryotic cells, how did mitochondria originate?
A) from infoldings of the plasma membrane, coupled with
mutations of genes for proteins in energy-transfer reactions
B) from engulfed, originally free-living proteobacteria
C) by secondary endosymbiosis
D) from the nuclear envelope folding outward and forming
mitochondrial membranes
E) when a protoeukaryote engaged in a symbiotic
relationship with a protocell
Answer: B
4) Which process could have allowed the nucleomorphs of
chlorarachniophytes to be reduced, without the net loss of any genetic
information?
A) conjugation
B) horizontal gene transfer
C) binary fission
D) phagocytosis
E) meiosis
Answer: B
5) An individual mixotroph loses its plastids, yet
continues to survive. Which of the following most likely accounts for its
continued survival?
A) It relies on photosystems that float freely in its
cytosol.
B) It must have gained extra mitochondria when it lost
its plastids.
C) It engulfs organic material by phagocytosis or by
absorption.
D) It has an endospore.
E) It is protected by a case made of silica.
Answer: C
6) Which of the following was derived from an ancestral
cyanobacterium?
A) chloroplast
B) mitochondrion
C) hydrogenosome
D) mitosome
E) Two of the responses above are correct.
Answer: A
7) Which two genera have members that can evade the human
immune system by frequently changing their surface proteins?
1. Plasmodium
2. Trichomonas
3. Paramecium
4. Trypanosoma
5. Entamoeba
A) 1 and 2
B) 1 and 4
C) 2 and 3
D) 2 and 4
E) 4 and 5
Answer: B
8) Which of the following pairs of protists and their
characteristics is mismatched?
A) apicomplexans–internal parasites
B) golden algae–planktonic producers
C) euglenozoans–unicellular flagellates
D) ciliates–red tide organisms
E) entamoebas–ingestive heterotrophs
Answer: D
9) Which of the following statements about
dinoflagellates is true?
A) They possess two flagella.
B) All known varieties are autotrophic.
C) Their walls are usually composed of silica plates.
D) Many types lack mitochondria.
E) Their dead cells accumulate on the seafloor, and are
mined to serve as a filtering material.
Answer: A
10) You are given an unknown organism to identify. It is
unicellular and heterotrophic. It is motile, using many short extensions of the
cytoplasm, each featuring the 9 + 2 filament pattern. It has well-developed
organelles and three nuclei, one large and two small. This organism is most
likely to be a member of which group?
A) foraminiferans
B) radiolarians
C) ciliates
D) kinetoplastids
E) slime molds
Answer: C
11) Which of the following is characteristic of ciliates?
A) They use pseudopods as locomotory structures or as
feeding structures.
B) They are relatively specialized cells.
C) They can exchange genetic material with other ciliates
by the process of mitosis.
D) Most live as solitary autotrophs in fresh water.
E) They are often multinucleate.
Answer: E
12) Which process results in genetic recombination, but
is separate from the process by which the population size of Paramecium
increases?
A) budding
B) meiotic division
C) mitotic division
D) conjugation
E) binary fission
Answer: D
13) Why is the filamentous morphology of the water molds
considered a case of convergent evolution?
A) Water molds evolved from filamentous fungi.
B) Body shape reflects ancestor-descendant relationships
among organisms.
C) In both cases, filamentous shape is an adaptation for
the absorptive nutritional mode of a decomposer.
D) Filamentous body shape is evolutionarily ancestral for
all eukaryotes.
E) Both the first and second responses above are correct.
Answer: C
14) If we were to apply the most recent technique used to
fight potato late blight to the fight against the malarial infection of humans,
then we would
A) increase the dosage of the least-expensive
antimalarial drug administered to humans.
B) increase the dosage of the most common pesticide used
to kill Anopheles mosquitoes.
C) introduce a predator of the malarial parasite into
infected humans.
D) use a "cocktail" of at least three different
pesticides against Anopheles mosquitoes.
E) insert genes from a Plasmodium-resistant strain of
mosquito into Anopheles mosquitoes.
Answer: E
15) Diatoms are mostly asexual members of the
phytoplankton. Diatoms lack any organelles that might have the 9 + 2 pattern.
They obtain their nutrition from functional chloroplasts, and each diatom is
encased within two porous, glasslike valves. Which question would be most
important for one interested in the day-to-day survival of individual diatoms?
A) How does carbon dioxide get into these protists with
their glasslike valves?
B) How do diatoms get transported from one location on
the water's surface layers to another location on the surface?
C) How do diatoms with their glasslike valves keep from
sinking into poorly lit waters?
D) How do diatoms with their glasslike valves avoid being
shattered by the action of waves?
E) How do diatom sperm cells locate diatom egg cells?
Answer: C
16) A large seaweed that floats freely on the surface of
deep bodies of water would be expected to lack which of the following?
A) thalli
B) bladders
C) holdfasts
D) gel-forming polysaccharides
Answer: C
17) Which of the following is a characteristic of the
water molds (oomycetes)?
A) the presence of filamentous feeding structures
B) zoospores that are spread by breezes
C) the same nutritional mode as possessed by
cyanobacteria
D) a morphological similarity to fungi that is the result
of common ancestry
E) a feeding Plasmodium
Answer: A
18) Reinforced, threadlike pseudopods that can perform
phagocytosis are generally characteristic of which group?
A) radiolarians and forams
B) gymnamoebas
C) entamoebas
D) amoeboid stage of cellular slime molds
E) oomycetes
Answer: A
19) A snail-like, coiled, porous test (shell) of calcium
carbonate is characteristic of which group?
A) diatoms
B) foraminiferans
C) radiolarians
D) gymnamoebas
Answer: B
20) The chloroplasts of land plants are thought to have
been derived according to which evolutionary sequence?
A) cyanobacteria → green algae → land plants
B) cyanobacteria → green algae → fungi → land plants
C) red algae → brown algae → green algae → land plants
D) cyanobacteria → red algae → green algae → land plants
Answer: A
21) The chloroplasts of all of the following are thought
to be derived from ancestral red algae, except those of
A) golden algae.
B) diatoms.
C) dinoflagellates.
D) green algae.
E) brown algae.
Answer: D
22) A biologist discovers an alga that is marine,
multicellular, and lives at a depth reached only by blue light. This alga
probably belongs to which group?
A) red algae
B) brown algae
C) green algae
D) dinoflagellates
E) golden algae
Answer: A
23) Green algae differ from land plants in that many
green algae
A) are heterotrophs.
B) are unicellular.
C) have plastids.
D) have alternation of generations.
E) have cell walls containing cellulose.
Answer: B
24) If the Archaeplastidae are eventually designated a
kingdom, and if land plants are excluded from this kingdom, then what will be
true of this new kingdom?
A) It will be monophyletic.
B) It will more accurately depict evolutionary
relationships than does the current taxonomy.
C) It will be paraphyletic.
D) It will be a true clade.
E) It will be polyphyletic.
Answer: C
25) The best evidence for not classifying the slime molds
as fungi comes from slime molds'
A) DNA sequences.
B) nutritional modes.
C) choice of habitats.
D) physical appearance.
E) reproductive methods.
Answer: A
26) Which pair of alternatives is highlighted by the life
cycle of the cellular slime molds, such as Dictyostelium?
A) prokaryotic or eukaryotic
B) unicellular or multicellular
C) diploid or haploid
D) autotroph or heterotroph
Answer: B
27) Which of the following statements concerning protists
is true?
A) All protists have mitochondria, though in some species
they are much reduced and known by different names.
B) The primary organism that transmits malaria to humans
by its bite is the tsetse fly.
C) All apicomplexans are autotrophic.
D) All slime molds have an amoeboid stage that may be
followed by a stage during which spores are produced.
E) Euglenozoans that are mixotrophic lack functional
chloroplasts.
Answer: A
28) Which of the following is correctly described as a
primary producer?
A) oomycete
B) kinetoplastid
C) apicomplexan
D) diatom
E) radiolarian
Answer: D
29) You are given the task of designing an aerobic,
mixotrophic protist that can perform photosynthesis in fairly deep water (for
example, 250 m deep), and can also crawl about and engulf small particles. With
which two of the following structures would you provide your protist?
1. hydrogenosome
2. apicoplast
3. pseudopods
4. chloroplast from red alga
5. chloroplast from green alga
A) 1 and 2
B) 2 and 3
C) 2 and 4
D) 3 and 4
E) 4 and 5
Answer: D
30) You are given the task of designing an aquatic
protist that is a primary producer. It cannot swim on its own, yet must stay in
well-lit surface waters. It must be resistant to physical damage from wave
action. It should be most similar to a(n)
A) diatom.
B) dinoflagellate.
C) apicomplexan.
D) red alga.
E) radiolarian.
Answer: A
31) Similar to most amoebozoans, the forams and the
radiolarians also have pseudopods, as do some of the white blood cells of
animals (monocytes). If one were to erect a taxon that included all organisms
that have cells with pseudopods, what would be true of such a taxon?
A) It would be polyphyletic.
B) It would be paraphyletic.
C) It would be monophyletic.
D) It would include all eukaryotes.
Answer: A
32) You are designing an artificial drug-delivery
"cell" that can penetrate animal cells. Which of these protist
structures should provide the most likely avenue for research along these
lines?
A) pseudopods
B) apical complex
C) excavated feeding grooves
D) nucleomorphs
E) mitosomes
Answer: B
33) A gelatinous seaweed that grows in shallow, cold
water and undergoes heteromorphic alternation of generations is most probably
what type of alga?
A) red
B) green
C) brown
D) yellow
Answer: C
34) Which of the following are actual mutualistic
partnerships that involve a protist and a host organism?
A) cellulose-digesting gut protistswood-eating
termites
B) dinoflagellatesreef-building
coral animals
C) Trichomonashumans
D) algaecertain foraminiferans
E) all except that involving humans
Answer: E
35) Living diatoms contain brownish plastids. If global
warming causes blooms of diatoms in the surface waters of Earth's oceans, how
might this be harmful to the animals that build coral reefs?
A) The coral animals, which capture planktonic organisms,
may be outcompeted by the diatoms.
B) The coral animals' endosymbiotic dinoflagellates may
get "shaded out" by the diatoms.
C) The coral animals may die from overeating the
plentiful diatoms, with their cases of silica.
D) The diatoms' photosynthetic output may over-oxygenate
the water.
Answer: B
36. You are given five test tubes, each containing an unknown
protist, and your task is to read the following description and match these
five protists to the correct test tube.
In test tube 1, you observe an organism feeding. Your
sketch of the organism looks very similar to Figure When light,
especially red and blue light, is shone on the tubes, oxygen bubbles accumulate
on the inside of test tubes 2 and 3. Chemical analysis of test tube 3 indicates
the presence of substantial amounts of silica. Chemical analysis of test tube 2
indicates the presence of a chemical that is toxic to fish and humans.
Microscopic analysis of organisms in test tubes 2, 4, and 5 reveals the
presence of permanent, membrane-bounded sacs just under the plasma membrane.
Microscopic analysis of organisms in test tube 4 reveals the presence of an
apicoplast in each. Microscopic analysis of the contents in test tube 5 reveals
the presence of one large nucleus and several small nuclei in each organism.
Test tube 2 contains
A) Paramecium.
B) Navicula (diatom).
C) Pfiesteria (dinoflagellate).
D) Entamoeba.
E) Plasmodium.
Answer: C
37. You are given five test tubes, each containing an unknown
protist, and your task is to read the following description and match these
five protists to the correct test tube.
In test tube 1, you observe an organism feeding. Your
sketch of the organism looks very similar to Figure When light,
especially red and blue light, is shone on the tubes, oxygen bubbles accumulate
on the inside of test tubes 2 and 3. Chemical analysis of test tube 3 indicates
the presence of substantial amounts of silica. Chemical analysis of test tube 2
indicates the presence of a chemical that is toxic to fish and humans.
Microscopic analysis of organisms in test tubes 2, 4, and 5 reveals the
presence of permanent, membrane-bounded sacs just under the plasma membrane.
Microscopic analysis of organisms in test tube 4 reveals the presence of an
apicoplast in each. Microscopic analysis of the contents in test tube 5 reveals
the presence of one large nucleus and several small nuclei in each organism.
37) Test tube 4 contains
A) Paramecium.
B) Navicula (diatom).
C) Pfiesteria (dinoflagellate).
D) Entamoeba.
E) Plasmodium.
Answer: E
38. You are given five test tubes, each containing an unknown
protist, and your task is to read the following description and match these
five protists to the correct test tube.
In test tube 1, you observe an organism feeding. Your
sketch of the organism looks very similar to Figure When light,
especially red and blue light, is shone on the tubes, oxygen bubbles accumulate
on the inside of test tubes 2 and 3. Chemical analysis of test tube 3 indicates
the presence of substantial amounts of silica. Chemical analysis of test tube 2
indicates the presence of a chemical that is toxic to fish and humans.
Microscopic analysis of organisms in test tubes 2, 4, and 5 reveals the
presence of permanent, membrane-bounded sacs just under the plasma membrane.
Microscopic analysis of organisms in test tube 4 reveals the presence of an
apicoplast in each. Microscopic analysis of the contents in test tube 5 reveals
the presence of one large nucleus and several small nuclei in each organism.
38) Test tube 5 contains
A) Paramecium.
B) Navicula (diatom).
C) Pfiesteria (dinoflagellate).
D) Entamoeba.
E) Plasmodium.
Answer: A
39. You are given five test tubes, each containing an unknown
protist, and your task is to read the following description and match these
five protists to the correct test tube.
In test tube 1, you observe an organism feeding. Your
sketch of the organism looks very similar to Figure When light,
especially red and blue light, is shone on the tubes, oxygen bubbles accumulate
on the inside of test tubes 2 and 3. Chemical analysis of test tube 3 indicates
the presence of substantial amounts of silica. Chemical analysis of test tube 2
indicates the presence of a chemical that is toxic to fish and humans.
Microscopic analysis of organisms in test tubes 2, 4, and 5 reveals the
presence of permanent, membrane-bounded sacs just under the plasma membrane.
Microscopic analysis of organisms in test tube 4 reveals the presence of an
apicoplast in each. Microscopic analysis of the contents in test tube 5 reveals
the presence of one large nucleus and several small nuclei in each organism.
Test tube 3 contains
A) Paramecium.
B) Navicula (diatom).
C) Pfiesteria (dinoflagellate).
D) Entamoeba.
E) Plasmodium.
Answer: B
40. Diatoms are encased in Petri-platelike cases (valves)
made of translucent hydrated silica whose thickness can be varied. The material
used to store excess calories can also be varied. At certain times, diatoms
store excess calories in the form of the liquid polysaccharide, laminarin, and
at other times as oil. The following are data concerning the density (specific
gravity) of various components of diatoms, and of their environment.
Table Specific Gravities of Materials Relevant to
Diatoms
Water's density and, consequently, its buoyancy
decrease at warmer temperatures. Based on this consideration and using data
from Table 28.1, at which time of year should one expect diatoms to be storing
excess calories mostly as oil?
A) mid-winter
B) early spring
C) late summer
D) late fall
Answer: C
41. Diatoms are encased in Petri-platelike cases (valves)
made of translucent hydrated silica whose thickness can be varied. The material
used to store excess calories can also be varied. At certain times, diatoms
store excess calories in the form of the liquid polysaccharide, laminarin, and
at other times as oil. The following are data concerning the density (specific
gravity) of various components of diatoms, and of their environment.
Table Specific Gravities of Materials Relevant to
Diatoms
Judging from Table 28.1 and given that water's
density and, consequently, its buoyancy decrease at warmer temperatures, in
which environment should diatoms (and other suspended particles) sink most
slowly?
A) cold fresh water
B) warm fresh water
C) cold seawater
D) warm seawater
E) warm brackish water
Answer: C
42. Diatoms are encased in Petri-platelike cases (valves)
made of translucent hydrated silica whose thickness can be varied. The material
used to store excess calories can also be varied. At certain times, diatoms
store excess calories in the form of the liquid polysaccharide, laminarin, and
at other times as oil. The following are data concerning the density (specific
gravity) of various components of diatoms, and of their environment.
Table Specific Gravities of Materials Relevant to
Diatoms
Using dead diatoms to "pump" CO2 to the
seafloor is feasible only if dead diatoms sink quickly. Consequently,
application of mineral fertilizers, such as iron, should be most effective at
times when diatom valves
A) are thickest, and laminarin is being produced rather
than oil.
B) are thickest, and oil is being produced rather than
laminarin.
C) are thinnest, and laminarin is being produced rather
than oil.
D) are thinnest, and oil is being produced rather than
laminarin.
Answer: A
43. Giardia lamblia is an intestinal parasite of humans and
other mammals that causes intestinal ailments in most people who ingest the
cysts. Upon ingestion, each cyst releases two motile cells, called
trophozoites. These attach to the small intestine's lining via a ventral
adhesive disk.
The trophozoites anaerobically metabolize glucose from the
host's intestinal contents to produce ATP. Reproduction is completely asexual,
occurring by longitudinal binary fission of trophozoites, with each daughter
cell receiving two, haploid nuclei (n = 5). A trophozoite will often encyst as
it passes into the large intestine by secreting around itself a case that is
resistant to cold, heat, and dehydration. Infection usually occurs by drinking
untreated water that contains cysts.
The trophozoites of Giardia were first observed in
1681 in the diarrhea stools of the first known person to view protists with a
microscope, a person named
A) Robert Koch.
B) Robert Hooke.
C) Isaac Newton.
D) van Leeuwenhoek.
E) Louis Pasteur.
Answer: D
44. Giardia lamblia is an intestinal parasite of humans and
other mammals that causes intestinal ailments in most people who ingest the
cysts. Upon ingestion, each cyst releases two motile cells, called
trophozoites. These attach to the small intestine's lining via a ventral
adhesive disk. The trophozoites anaerobically metabolize glucose from the
host's intestinal contents to produce ATP. Reproduction is completely asexual,
occurring by longitudinal binary fission of trophozoites, with each daughter
cell receiving two, haploid nuclei (n = 5). A trophozoite will often encyst as
it passes into the large intestine by secreting around itself a case that is
resistant to cold, heat, and dehydration. Infection usually occurs by drinking
untreated water that contains cysts.
Given that Flagyl produces only minor side effects
(if any) in humans, and given the set of parasites that it kills, Flagyl's mode
of action probably involves
A) peptidoglycan.
B) mitochondria or mitosomes.
C) anaerobic metabolic pathways.
D) nuclear envelopes.
E) microtubules.
Answer: C
45. Giardia lamblia is an intestinal parasite of humans and
other mammals that causes intestinal ailments in most people who ingest the
cysts. Upon ingestion, each cyst releases two motile cells, called trophozoites.
These attach to the small intestine's lining via a ventral adhesive disk. The
trophozoites anaerobically metabolize glucose from the host's intestinal
contents to produce ATP. Reproduction is completely asexual, occurring by
longitudinal binary fission of trophozoites, with each daughter cell receiving
two, haploid nuclei (n = 5). A trophozoite will often encyst as it passes into
the large intestine by secreting around itself a case that is resistant to
cold, heat, and dehydration. Infection usually occurs by drinking untreated
water that contains cysts.
Giardia's mitosome can be said to be "doubly
degenerate," because it is a degenerate form of
________, an organelle that is itself a degenerate form of ________.
A) nucleus; archaean
B) nucleus; bacterium
C) mitochondrion; proteobacterium
D) mitochondrion; spirochete
E) chloroplast; cyanobacterium
Answer: C
46. Giardia lamblia is an intestinal parasite of humans and
other mammals that causes intestinal ailments in most people who ingest the
cysts. Upon ingestion, each cyst releases two motile cells, called
trophozoites. These attach to the small intestine's lining via a ventral
adhesive disk. The trophozoites anaerobically metabolize glucose from the
host's intestinal contents to produce ATP. Reproduction is completely asexual,
occurring by longitudinal binary fission of trophozoites, with each daughter
cell receiving two, haploid nuclei (n = 5). A trophozoite will often encyst as
it passes into the large intestine by secreting around itself a case that is
resistant to cold, heat, and dehydration. Infection usually occurs by drinking
untreated water that contains cysts.
The mitosome of Giardia has no DNA within it. If it
did contain DNA, then what predictions should we be able to make about its DNA?
1. It is linear.
2. It is circular.
3. It has many introns.
4. It has few introns.
5. It is not associated with histone proteins.
6. It is complexed with histone proteins.
A) 1, 3, and 5
B) 1, 4, and 5
C) 2, 3, and 6
D) 2, 4, and 5
E) 2, 4, and 6
Answer: D
47. Giardia lamblia is an intestinal parasite of humans and
other mammals that causes intestinal ailments in most people who ingest the
cysts. Upon ingestion, each cyst releases two motile cells, called
trophozoites. These attach to the small intestine's lining via a ventral
adhesive disk. The trophozoites anaerobically metabolize glucose from the
host's intestinal contents to produce ATP. Reproduction is completely asexual,
occurring by longitudinal binary fission of trophozoites, with each daughter
cell receiving two, haploid nuclei (n = 5). A trophozoite will often encyst as
it passes into the large intestine by secreting around itself a case that is
resistant to cold, heat, and dehydration. Infection usually occurs by drinking
untreated water that contains cysts.
Given the putative ancestry of Giardia's mitosome,
what should we predict is true of the mitosome?
A) It has electron transport systems that use oxygen as
the final electron acceptor.
B) It has a double membrane.
C) It has thylakoids.
D) It contains microtubules, arranged in the "9 + 2
pattern."
E) It contains 80S (eukaryotic) ribosomes.
Answer: B
48. Giardia lamblia is an intestinal parasite of humans and
other mammals that causes intestinal ailments in most people who ingest the
cysts. Upon ingestion, each cyst releases two motile cells, called
trophozoites. These attach to the small intestine's lining via a ventral
adhesive disk. The trophozoites anaerobically metabolize glucose from the
host's intestinal contents to produce ATP. Reproduction is completely asexual,
occurring by longitudinal binary fission of trophozoites, with each daughter
cell receiving two, haploid nuclei (n = 5). A trophozoite will often encyst as
it passes into the large intestine by secreting around itself a case that is
resistant to cold, heat, and dehydration. Infection usually occurs by drinking
untreated water that contains cysts.
Given its mode of reproduction and internal
structures, which of the following should be expected to occur in Giardia at
some stage of its life cycle?
1. separation (segregation) of daughter chromosomes
2. crossing over
3. meiosis
A) 1 only
B) 3 only
C) 1 and 2
D) 1 and 3
E) 2 and 3
Answer: A
49. Giardia lamblia is an intestinal parasite of humans and
other mammals that causes intestinal ailments in most people who ingest the
cysts. Upon ingestion, each cyst releases two motile cells, called
trophozoites. These attach to the small intestine's lining via a ventral adhesive
disk. The trophozoites anaerobically metabolize glucose from the host's
intestinal contents to produce ATP. Reproduction is completely asexual,
occurring by longitudinal binary fission of trophozoites, with each daughter
cell receiving two, haploid nuclei (n = 5). A trophozoite will often encyst as
it passes into the large intestine by secreting around itself a case that is
resistant to cold, heat, and dehydration. Infection usually occurs by drinking
untreated water that contains cysts.
Unlike most excavates, Giardia trophozoites have no
oral groove and are unable to form food vacuoles. Thus, we should expect its
nutrition (mostly glucose) to come from
A) its mitosomes.
B) endosymbiotic cyanobacteria.
C) the ventral disk by which it adheres to the intestinal
lining.
D) osmosis involving aquaporins.
E) plasma membrane proteins that are transporters or
pumps.
Answer: E
50. Giardia lamblia is an intestinal parasite of humans and
other mammals that causes intestinal ailments in most people who ingest the
cysts. Upon ingestion, each cyst releases two motile cells, called
trophozoites. These attach to the small intestine's lining via a ventral
adhesive disk. The trophozoites anaerobically metabolize glucose from the
host's intestinal contents to produce ATP. Reproduction is completely asexual,
occurring by longitudinal binary fission of trophozoites, with each daughter
cell receiving two, haploid nuclei (n = 5). A trophozoite will often encyst as
it passes into the large intestine by secreting around itself a case that is
resistant to cold, heat, and dehydration. Infection usually occurs by drinking
untreated water that contains cysts.
Diplomonads, such as Giardia, contain two haploid
nuclei per trophozoite. Thus, during the G1 phase of the cell cycle, there
should be a total of how many unreplicated chromosomes per trophozoite, and
during the G2 phase, how many replicated chromosomes per trophozoite?
A) 5; 5
B) 5; 10
C) 10; 10
D) 10; 20
E) 20; 20
Answer: C
51. Giardia lamblia is an intestinal parasite of humans and
other mammals that causes intestinal ailments in most people who ingest the
cysts. Upon ingestion, each cyst releases two motile cells, called
trophozoites. These attach to the small intestine's lining via a ventral
adhesive disk. The trophozoites anaerobically metabolize glucose from the
host's intestinal contents to produce ATP. Reproduction is completely asexual,
occurring by longitudinal binary fission of trophozoites, with each daughter cell
receiving two, haploid nuclei (n = 5). A trophozoite will often encyst as it
passes into the large intestine by secreting around itself a case that is
resistant to cold, heat, and dehydration. Infection usually occurs by drinking
untreated water that contains cysts.
During passage through the large intestine, a
trophozoite will often secrete a case around itself, forming a cyst. Cysts
contain four haploid nuclei. When cysts "hatch" within a new host,
two trophozoites are released. Thus, which of the following must happen within
the cyst, prior to hatching?
1. meiosis
2. nuclear division
3. S phase
4. binary fission
A) 1 only
B) 1 and 2
C) 2 and 3
D) 2 and 4
E) 2, 3, and 4
Answer: E
52. Giardia lamblia is an intestinal parasite of humans and
other mammals that causes intestinal ailments in most people who ingest the
cysts. Upon ingestion, each cyst releases two motile cells, called
trophozoites. These attach to the small intestine's lining via a ventral
adhesive disk. The trophozoites anaerobically metabolize glucose from the
host's intestinal contents to produce ATP. Reproduction is completely asexual,
occurring by longitudinal binary fission of trophozoites, with each daughter
cell receiving two, haploid nuclei (n = 5). A trophozoite will often encyst as
it passes into the large intestine by secreting around itself a case that is
resistant to cold, heat, and dehydration. Infection usually occurs by drinking
untreated water that contains cysts.
The cysts of Giardia are most analogous to the
A) mitochondria of ancestral diplomonads.
B) nuclei of archaeans.
C) endospores of bacteria.
D) capsids of viruses.
Answer: C
53. Giardia lamblia is an intestinal parasite of humans and
other mammals that causes intestinal ailments in most people who ingest the
cysts. Upon ingestion, each cyst releases two motile cells, called
trophozoites. These attach to the small intestine's lining via a ventral
adhesive disk. The trophozoites anaerobically metabolize glucose from the
host's intestinal contents to produce ATP. Reproduction is completely asexual,
occurring by longitudinal binary fission of trophozoites, with each daughter
cell receiving two, haploid nuclei (n = 5). A trophozoite will often encyst as
it passes into the large intestine by secreting around itself a case that is
resistant to cold, heat, and dehydration. Infection usually occurs by drinking
untreated water that contains cysts.
If the mitosomes of Giardia contain no DNA, yet are descendants
of what were once free-living organisms, then where are we likely to find the
genes that encode their structures, and what accounts for their current
location there?
A) plasmids; conjugation
B) plasmids; transformation
C) nucleus; horizontal gene transfer
D) nucleus; S phase
Answer: C
54. Giardia lamblia is an intestinal parasite of humans and
other mammals that causes intestinal ailments in most people who ingest the
cysts. Upon ingestion, each cyst releases two motile cells, called trophozoites.
These attach to the small intestine's lining via a ventral adhesive disk. The
trophozoites anaerobically metabolize glucose from the host's intestinal
contents to produce ATP. Reproduction is completely asexual, occurring by
longitudinal binary fission of trophozoites, with each daughter cell receiving
two, haploid nuclei (n = 5). A trophozoite will often encyst as it passes into
the large intestine by secreting around itself a case that is resistant to
cold, heat, and dehydration. Infection usually occurs by drinking untreated
water that contains cysts.
The primary treatment for giardiasis (infection with
Giardia), as well as for trichomoniasis (infection with Trichomonas vaginalis)
and for amoebic dysentery (infection with Entamoeba histolytica), is a drug
marketed as Flagyl (generic name is metronidazole). The drug also kills
anaerobic gut bacteria. Consequently, which of these are cues that Flagyl's
mode of action has nothing to do with attacking or disabling the parasites'
flagella, as the drug's name might imply?
1. It would also harm the flagellated lining of the human
intestine.
2. Entamoeba possesses pseudopods, not flagella, yet it
is killed by Flagyl.
3. Prokaryotic flagella and eukaryotic flagella are
radically different from each other and unlikely to be harmed by the same
chemical.
4. Not all anaerobic gut bacteria possess flagella, yet
it kills these bacteria.
A) 1 and 2
B) 1 and 3
C) 2 and 3
D) 1, 2, and 4
E) 2, 3, and 4
Answer: E
55. Paulinella chromatophora is one of the few cercozoans
that is autotrophic, carrying out aerobic photosynthesis with its two elongated
"cyanelles." The cyanelles are contained within vesicles of the host
cell, and each is derived from a cyanobacterium, though not the same type of
cyanobacterium that gave rise to the chloroplasts of algae and plants.
The closest living relative of P. chromatophora is
the heterotroph, P. ovalis. What type of evidence permits biologists to make
this claim about relatedness?
A) morphological
B) ecological
C) biochemical
D) genetic
E) fossil
Answer: D
56. Paulinella chromatophora is one of the few cercozoans
that is autotrophic, carrying out aerobic photosynthesis with its two elongated
"cyanelles." The cyanelles are contained within vesicles of the host
cell, and each is derived from a cyanobacterium, though not the same type of
cyanobacterium that gave rise to the chloroplasts of algae and plants.
The closest living relative of P. chromatophora is
the heterotroph, P. ovalis. P. ovalis uses threadlike pseudopods to capture its
prey, which it digests internally. Which of the following, if observed, would
be the best reason for relabeling P. chromatophora as a mixotroph?
A) a threadlike pseudopod
B) a pigmented central vacuole, surrounded by a tonoplast
C) a vacuole with food inside
D) a secretory vesicle
E) a contractile vacuole
Answer: C
57. Paulinella chromatophora is one of the few cercozoans
that is autotrophic, carrying out aerobic photosynthesis with its two elongated
"cyanelles." The cyanelles are contained within vesicles of the host
cell, and each is derived from a cyanobacterium, though not the same type of
cyanobacterium that gave rise to the chloroplasts of algae and plants.
P. chromatophora secretes around itself a test, or
case, of plates made of silica. Which of the following is another rhizarian
that would be in competition with P. chromatophora for the silica needed to
make these plates, assuming limited quantities of silica in the environment?
A) radiolarians
B) foraminiferans
C) all other amoeboid cells
D) all other rhizaria
E) diatoms
Answer: A
58. Paulinella chromatophora is one of the few cercozoans
that is autotrophic, carrying out aerobic photosynthesis with its two elongated
"cyanelles." The cyanelles are contained within vesicles of the host
cell, and each is derived from a cyanobacterium, though not the same type of
cyanobacterium that gave rise to the chloroplasts of algae and plants.
Which of the following represents the true
significance of the finding that the cyanelles of P. chromatophora stem from a
different type of cyanobacterium than gave rise to chloroplasts?
A) This finding indicates that there is a second
evolutionary lineage of photosynthetic eukaryotes.
B) This finding represents the first time that primary
endosymbiosis has been directly observed.
C) This finding is the strongest evidence yet for the
theory of endosymbiosis.
D) This finding is an example of the phenomenon known as
"serial endosymbiosis."
E) This finding is the first evidence that eukaryotic
cells do not necessarily digest prokaryotic cells that manage to gain access to
their cytoplasm.
Answer: A
59. Paulinella chromatophora is one of the few cercozoans
that is autotrophic, carrying out aerobic photosynthesis with its two elongated
"cyanelles." The cyanelles are contained within vesicles of the host
cell, and each is derived from a cyanobacterium, though not the same type of
cyanobacterium that gave rise to the chloroplasts of algae and plants.
The genome of modern chloroplasts is roughly 50% the
size of the genome of the cyanobacterium from which it is thought to have been
derived. In comparison, the genome of P. chromatophora's cyanelle is only
slightly reduced relative to the size of the genome of the cyanobacterium from
which it is thought to have been derived. What is a valid conclusion that can be
drawn from this comparison?
A) Lytic phage infections have targeted the chloroplast
genome more often than the P. chromatophora genome.
B) P. chromatophora's cyanelle is the result of an
evolutionarily recent endosymbiosis.
C) The genome of the chloroplast ancestor contained many
more introns that could be lost without harm, compared to the cyanelle's
genome.
D) All three of the conclusions above are valid.
E) Two of the conclusions above are valid.
Answer: B
60. Paulinella chromatophora is one of the few cercozoans
that is autotrophic, carrying out aerobic photosynthesis with its two elongated
"cyanelles." The cyanelles are contained within vesicles of the host
cell, and each is derived from a cyanobacterium, though not the same type of
cyanobacterium that gave rise to the chloroplasts of algae and plants.
If true, which of the following would be most
important in determining whether P. chromatophora's cyanelle is still an
endosymbiont, or is an organelle, as the term cyanelle implies?
A) If P. chromatophora is less fit without its cyanelle
than with it.
B) If the cyanelle is less fit without the host cercozoan
than with it.
C) If there is ongoing metabolic cooperation between the
cyanelle and the host cercozoan.
D) If the magnesium-containing porphyrin ring in the
cyanelle's chlorophyll molecules is built by the cyanelle, whereas the organic
portion of the chlorophyll molecules is built by the host cercozoan.
E) If there has been movement of genes from the cyanelle
genome to the nuclear genome, such that these genes are no longer present in
the cyanelle genome.
Answer: E
61. Paulinella chromatophora is one of the few cercozoans
that is autotrophic, carrying out aerobic photosynthesis with its two elongated
"cyanelles." The cyanelles are contained within vesicles of the host
cell, and each is derived from a cyanobacterium, though not the same type of
cyanobacterium that gave rise to the chloroplasts of algae and plants.
If true, which of the following is the best evidence
that the cyanelles are providing nutrition (in other words, calories) to the
surrounding cercozoan?
A) If the cyanelle performs aerobic photosynthesis.
B) If the vesicle membrane that surrounds each cyanelle
possesses glucose-transport proteins.
C) If the cyanelle performs aerobic respiration.
D) If radiolabeled 14CO2 enters the cyanelle and if,
subsequently, radiolabeled glucose is present in cercozoan cytosol.
E) If radiolabeled "heavy" water, 2H2O, enters
the cyanelle and if, subsequently, radiolabeled oxygen appears in cercozoan
cytosol.
Answer: D
62. Paulinella chromatophora is one of the few cercozoans
that is autotrophic, carrying out aerobic photosynthesis with its two elongated
"cyanelles." The cyanelles are contained within vesicles of the host
cell, and each is derived from a cyanobacterium, though not the same type of
cyanobacterium that gave rise to the chloroplasts of algae and plants.
A crucial photosynthetic gene of the cyanobacterium
that gave rise to the cyanelle is called psaE. This gene is present in the
nuclear genome of the cercozoan, but is not in the genome of the cyanelle. This
is evidence of
A) reciprocal mutations in the cyanelle and nuclear
genomes.
B) horizontal gene transfer from bacterium to eukaryotes.
C) genetic recombination involving a protist and an
archaean.
D) the origin of photosynthesis in protists.
E) transduction by a phage that infects both prokaryotes
and eukaryotes.
Answer: B
63. Paulinella chromatophora is one of the few cercozoans
that is autotrophic, carrying out aerobic photosynthesis with its two elongated
"cyanelles." The cyanelles are contained within vesicles of the host
cell, and each is derived from a cyanobacterium, though not the same type of
cyanobacterium that gave rise to the chloroplasts of algae and plants.
What must occur for asexual reproduction to be
successful in P. chromatophora?
1. mitosis
2. S phase
3. meiosis
4. equal distribution of cyanelles during cytokinesis
A) 1 only
B) 1 and 2
C) 1, 2, and 3
D) 1, 2, and 4
E) 2, 3, and 4
Answer: D
64. Paulinella chromatophora is one of the few cercozoans
that is autotrophic, carrying out aerobic photosynthesis with its two elongated
"cyanelles." The cyanelles are contained within vesicles of the host
cell, and each is derived from a cyanobacterium, though not the same type of
cyanobacterium that gave rise to the chloroplasts of algae and plants.
Including the membrane of the surrounding vesicle,
how many phospholipid (NOT lipopolysaccharide) bilayers should be found around
each cyanelle, and which one of these bilayers should have photosystems
embedded in it?
A) two; innermost
B) two; outermost
C) three; innermost
D) three; middle
E) three; outermost
Answer: A
Healthy individuals of Paramecium bursaria contain photosynthetic
algal endosymbionts of the genus Chlorella. When within their hosts, the algae
are referred to as zoochlorellae. In aquaria with light coming from only one
side, P. bursaria gathers at the well-lit side, whereas other species of
Paramecium gather at the opposite side. The zoochlorellae provide their hosts
with glucose and oxygen, and P. bursaria provides its zoochlorellae with
protection and motility. P. bursaria can lose its zoochlorellae in two ways:
(1) if kept in darkness, the algae will die; and (2) if prey items (mostly
bacteria) are absent from its habitat, P. bursaria will digest its
zoochlorellae.
65) Which term most accurately describes the nutritional
mode of healthy P. bursaria?
A) photoautotroph
B) photoheterotroph
C) chemoheterotroph
D) chemoautotroph
E) mixotroph
Answer: E
66. Healthy individuals of Paramecium bursaria contain
photosynthetic algal endosymbionts of the genus Chlorella. When within their
hosts, the algae are referred to as zoochlorellae. In aquaria with light coming
from only one side, P. bursaria gathers at the well-lit side, whereas other
species of Paramecium gather at the opposite side. The zoochlorellae provide
their hosts with glucose and oxygen, and P. bursaria provides its zoochlorellae
with protection and motility. P. bursaria can lose its zoochlorellae in two
ways: (1) if kept in darkness, the algae will die; and (2) if prey items
(mostly bacteria) are absent from its habitat, P. bursaria will digest its
zoochlorellae.
Which term accurately describes the behavior of
Paramecium species that lack zoochlorellae in an aquarium with light coming
from one side only?
A) positive chemotaxis
B) negative chemotaxis
C) positive phototaxis
D) negative phototaxis
Answer: D
67. Healthy individuals of Paramecium bursaria contain
photosynthetic algal endosymbionts of the genus Chlorella. When within their
hosts, the algae are referred to as zoochlorellae. In aquaria with light coming
from only one side, P. bursaria gathers at the well-lit side, whereas other
species of Paramecium gather at the opposite side. The zoochlorellae provide
their hosts with glucose and oxygen, and P. bursaria provides its zoochlorellae
with protection and motility. P. bursaria can lose its zoochlorellae in two
ways: (1) if kept in darkness, the algae will die; and (2) if prey items
(mostly bacteria) are absent from its habitat, P. bursaria will digest its
zoochlorellae.
Which term best describes the symbiotic relationship
of well-fed P. bursaria to their zoochlorellae?
A) mutualistic
B) commensal
C) parasitic
D) predatory
E) pathogenic
Answer: A
68. Healthy individuals of Paramecium bursaria contain
photosynthetic algal endosymbionts of the genus Chlorella. When within their
hosts, the algae are referred to as zoochlorellae. In aquaria with light coming
from only one side, P. bursaria gathers at the well-lit side, whereas other
species of Paramecium gather at the opposite side. The zoochlorellae provide
their hosts with glucose and oxygen, and P. bursaria provides its zoochlorellae
with protection and motility. P. bursaria can lose its zoochlorellae in two
ways: (1) if kept in darkness, the algae will die; and (2) if prey items
(mostly bacteria) are absent from its habitat, P. bursaria will digest its
zoochlorellae.
The motility that permits P. bursaria to move toward
a light source is provided by
A) pseudopods.
B) a single flagellum composed of the protein, flagellin.
C) a single flagellum featuring the 9 + 2 pattern.
D) many cilia.
E) contractile vacuoles.
Answer: D
69. Healthy individuals of Paramecium bursaria contain
photosynthetic algal endosymbionts of the genus Chlorella. When within their
hosts, the algae are referred to as zoochlorellae. In aquaria with light coming
from only one side, P. bursaria gathers at the well-lit side, whereas other
species of Paramecium gather at the opposite side. The zoochlorellae provide
their hosts with glucose and oxygen, and P. bursaria provides its zoochlorellae
with protection and motility. P. bursaria can lose its zoochlorellae in two
ways: (1) if kept in darkness, the algae will die; and (2) if prey items
(mostly bacteria) are absent from its habitat, P. bursaria will digest its
zoochlorellae.
A P. bursaria cell that has lost its zoochlorellae is
said to be aposymbiotic. It might be able to replenish its contingent of
zoochlorellae by ingesting them without subsequently digesting them. Which of
the following situations would be most favorable to the reestablishment of
resident zoochlorellae, assuming compatible Chlorella are present in P.
bursaria's habitat?
A) abundant light, no bacterial prey
B) abundant light, abundant bacterial prey
C) no light, no bacterial prey
D) no light, abundant bacterial prey
Answer: B
70. Healthy individuals of Paramecium bursaria contain
photosynthetic algal endosymbionts of the genus Chlorella. When within their
hosts, the algae are referred to as zoochlorellae. In aquaria with light coming
from only one side, P. bursaria gathers at the well-lit side, whereas other
species of Paramecium gather at the opposite side. The zoochlorellae provide
their hosts with glucose and oxygen, and P. bursaria provides its zoochlorellae
with protection and motility. P. bursaria can lose its zoochlorellae in two
ways: (1) if kept in darkness, the algae will die; and (2) if prey items
(mostly bacteria) are absent from its habitat, P. bursaria will digest its
zoochlorellae.
A P. bursaria cell that has lost its zoochlorellae is
aposymbiotic. If aposymbiotic cells have population growth rates the same as
those of healthy, zoochlorella-containing P. bursaria in well-lit environments
with plenty of prey items, then such an observation would be consistent with
which type of relationship?
A) parasitic
B) commensalistic
C) toxic
D) predator-prey
E) mutualistic
Answer: B
71. Healthy individuals of Paramecium bursaria contain
photosynthetic algal endosymbionts of the genus Chlorella. When within their
hosts, the algae are referred to as zoochlorellae. In aquaria with light coming
from only one side, P. bursaria gathers at the well-lit side, whereas other
species of Paramecium gather at the opposite side. The zoochlorellae provide
their hosts with glucose and oxygen, and P. bursaria provides its zoochlorellae
with protection and motility. P. bursaria can lose its zoochlorellae in two
ways: (1) if kept in darkness, the algae will die; and (2) if prey items
(mostly bacteria) are absent from its habitat, P. bursaria will digest its
zoochlorellae.
Theoretically, P.bursaria can obtain zoochlorella
either vertically (via the asexual reproduction of its mother cell) or
horizontally (by ingesting free-living Chlorella from its habitat). Consider a
P. bursaria cell containing zoochlorellae, but whose habitat lacks free-living
Chlorella. If this cell subsequently undergoes many generations of asexual
reproduction, if all of its daughter cells contain roughly the same number of
zoochlorellae as it had originally contained, and if the zoochlorellae are all
haploid and identical in appearance, then what is true?
A) The zoochlorellae also reproduced asexually, at an
increasing rate over time.
B) The zoochlorellae also reproduced asexually, at a
decreasing rate over time.
C) The zoochlorellae also reproduced asexually, at a
fairly constant rate over time.
D) The zoochlorellae reproduced sexually, undergoing
heteromorphic alternation of generations.
E) The zoochlorellae reproduced sexually, undergoing
isomorphic alternation of generations.
Answer: C
72) Plastids that are surrounded by more than two membranes
are evidence of
A) evolution from mitochondria.
B) fusion of plastids.
C) origin of the plastids from archaea.
D) secondary endosymbiosis.
E) budding of the plastids from the nuclear envelope.
Answer: D
73) Biologists suspect that endosymbiosis gave rise to
mitochondria before plastids partly because
A) the products of photosynthesis could not be
metabolized without mitochondrial enzymes.
B) all eukaryotes have mitochondria (or their remnants),
whereas many eukaryotes do not have plastids.
C) mitochondrial DNA is less similar to prokaryotic DNA
than is plastid DNA.
D) without mitochondrial CO₂ production, photosynthesis
could not occur.
E) mitochondrial proteins are synthesized on cytosolic
ribosomes, whereas plastids utilize their own ribosomes.
Answer: B
74) Which group is incorrectly paired with its
description?
A) rhizariansmorphologically
diverse group defined by DNA similarities
B) diatomsimportant producers in
aquatic communities
C) red algaeacquired plastids by
secondary endosymbiosis
D) apicomplexansparasites with
intricate life cycles
E) diplomonadsprotists with
modified mitochondria
Answer: C
75) Which protists are in the same eukaryotic supergroup
as land plants?
A) green algae
B) dinoflagellates
C) red algae
D) brown algae
E) both green algae and red algae
Answer: E
76) In life cycles with an alternation of generations,
multicellular haploid forms alternate with
A) unicellular haploid forms.
B) unicellular diploid forms.
C) multicellular haploid forms.
D) multicellular diploid forms.
E) multicellular polyploid forms.
Answer: D
DETAIL
LEBIH RINCINYA DEMIKIAN ok
DETAIL
Protista merupakan salah satu dari Kingdom dari Protista yang dipisahkan dari Kingdom Animalia, setelah dicanangkan Whitaker (1969) bahwa Mahkluk hidup terbagi menjadi 5 Kingdom yang mempunyai anggota yang beragam.
Terdapat tiga kelompok anggota Protista,
yaitu
- ganggang (algae),
- protozoa
- kapang lendir dan jamur air
Protozoa menempati habitat pada bermacam-macam tipe
perairan.
Protozoa mempunyai 4 kelompok taksonomi, yaitu
Flagellata, Amoeba, Ciliata, dan Sporozoa. Flagellata ditandai dengan adanya satu atau
lebih flagella dalam tubuhnya, hidup bebas atau sebagai parasit. Sebagai
contoh adalah Pteromonas, Euglena, dll. Amoeba tidak mempunyai alat lokomosi permanen,
pergerakan dilakukan dengan pseudopodia (kaki semu) yang merupakan perpanjangan dari
selnya, mengambil
makanan atau mangsa dengan menggunakan kaki semunya dan
makanan kemudian
masuk dalam vakuola makanan. Ciliata ditandai dengan
adanya silia diseluruh
permukaan tubuhnya. Silia ini digunakan untuk membantu
pergerakan dan memasukkan
makanan. Hampir semua anggota Ciliata hidup bebas. Contoh
yang umum dijumpai
adalah Paramaecium sp. Paramaecium mempunyai dua bahan
genetik, yaitu
makronukleus tunggal yang berperan dalam mengontrol
aktifitas sehari-hari, dan
mikronukleus poliplod (dengan 1-80) dan berperan dalam
reproduksi seksual.
Sporozoa dengan anggota bersifat parasit dan banyak
sebagai penyebab penyakit
pada manusia. Sebagai contohnya adalah Plasmodium.
Dalam praktikum ini juga dipelajari cara penyiapan
preparat basah untuk mengamati
mikroorganisme dalam keadaan hidup.Teknik yang dapat
digunakan adalah teknik
lekapan basah, tetes gantung, dan penggunaan agar
motilitas. Dalam praktikum ini anda akan menggunakan teknik lekapan basah.
Preparat yang bersifat basah yang anda siapkan
memungkinkan anda mengamati bentuk dan ukuran
mikroorganisme secara individu dan
motilitasnya dalam keadaan alamiah.
Anda akan dapat membedakan motilitas mikroorganisme yang
anda amati dengan gerak
Brown. Pergerakan sejati (motilitas) biasanya sangat
cepat dan terarah. Sedangkan gerak
Brown merupakan gerakan menggetar partikel-partikel dalam
cairan secara acak/tidak
terarah dan terus menerus. Hal ini menyebabkan
mikroorganisme motil dan non motil
berubah posisinya dan terlihat seperti bergerak. Dalam
pengamatan ini anda harus juga
membedakan pergerakan sejati dengan pergerakan yang
disebabkan oleh arus cairan.
Keadaan ini disebabkan karena preparat basah yang anda
buat mengandung gelembung
udara atau tidak tersegel dengan baik, sehingga timbul
arus udara yang menyebabkan
mikroorganisme yang anda amati bergerak mengalir
mengikuti arus cairan tersebut.
Pergerakan sejati mikroorganisme disebabkan karena adanya
flagela (bakteri, beberapa
ganggang, dan protozoa), adanya silia atau pseudopodia
(pergerakan amuboid) pada
beberapa protozoa. Flagella mungkin sukar untuk diamati
dengan mikroskup cahaya.
Pada pewarnaan khusus atau pengamatan dengan menggunakan
mikroskup elektron
flagela ini akan dengan mudah diamati.LEBIH RINCINYA DEMIKIAN ok
Protista adalah organisme eukariotik yaitu
bahan intinya yang terdapat di dalam selnya diselubungi oleh membran
inti. Protista sebagian besar bersel satu (uniseluler) sampai bersel banyak
(multiseluler) dan hidup soliter atau berkoloni, besama-sama namun tidak
menunjukan diferensiasi menjadi jaringan yang berbeda-beda. Protista dapat
ditemukan di air laut, tawar, atau menempel pada tempat-tempat basah.
Protista dapat digolongkan
menjadi protista mirip hewan (protozoa), protista mirip
tumbuhan (alga) dan protista mirip jamur,dan berdasarkan
caranya memperoleh makanan protista dikelompokkan atas:
1) Protista autotrof, yaitu
protista yang mempunyai klorofil sehingga dapat membuat makanan sendiri melalui
fotosintesis. Fotosintesis merupakan proses pembentukan senyawa organik dari
senyawa anorganik menggunakan energi cahaya.
2) Protista heterotrof, yaitu
protista yang tidak dapat membuat makanan sendiri sehingga memerlukan makanan
organik dari lingkungannya dengan cara fagositosis, fagositisis yaitu proses
memakan makhluk hidup lain dengan cara memasukan makhluk hidup yang akan
dimakan tersebut ke dalam sel.
3) Protista saprofit dan parasit,
saprofit artinya mencerna makanan organik di luar sel dari sisa-sisa makhluk
hidup yang telah mati, sedangkan parasit artinya menyerap sari-sari makanan
dari makhluk hidup inangnya. Contoh : jamur.
1. Protozoa, protista mirip hewan.
a. Ciri-ciri Protozoa
Protozoa berasal dari bahasa
yunani yaitu protos : mula-mula, awal, dan zoon :
hewan. Protozoa merupakan organisme bersel satu (uniseluler) yang mempunyai
inti eukariotik, protozoa berukuran antara 100 – 300 mikron dan memiliki bentuk
bervariasi mulai dari asimetris, bilateral simetris, radial simetris, dan
spiral. Protozoa hidup soliter maupun berkoloni.
Pada umumnya sel protozoa
terdiri atas membran sel, sitoplasma, vakuola makanan, vakuola kontraktil, dan
inti sel, dimana membran berfungsi sebagai pelindung dan pengatur pertukaran
makanan dan gas, sitoplasma merupakan cairan dalam membran sel,
vakuola makanan adalah vakuola untuk pencernaan makanan yang masuk melalui
membran sel atau sitoplasma, vakuola kontraktil berfungsi mengeluarkan sias
makanan berbentuk cair, sedangkan inti sel berfungsi untuk mengatur aktivitas
sel.
Protozoa umumnya memiliki
habitat di tempat-tempat berair dan basah seperti di air tawar, air laut,
tempat lembab, bahkan dalam tubuh hewan maupun manusia. Alat gerak pada
protozoa antara lain flagella (rambut/bulu cambuk), silia (rambut/bulu getar),
pseudopodia (kaki semu/kaki akar) dan ada yang tidak memiliki alat gerak.
Reproduksi pada protozoa
secara aseksual maupun seksual. Reproduksi aseksual adalah dengan cara
pembelahan biner, sedangkan seksual dengan cara konjugasi. Pada protozoa
respirasi dilakukan di seluruh permukaan tubuh dengan cara difusi. Apabila
keadaan tidak menguntungkan beberapa protozoa membentuk sel aktif yang disebut kista yang
diselubungi kapsul polisakarida.
b. Klasifikasi Protozoa
Berdasarkan alat geraknya
protozoa dapat diklasifikasikan menjadi 6 filum yaitu : Rhizopoda (sarcodina),
Cilliata, Zooflagellata (zoomastigophora), Sporozoa (apicomplexa),
Foraminifera, dan Actinopoda.
1) Filum Rhizopoda (sarcodina)
Rhizopoda berasal dari kata rhizo ;
akar, dan podos ; kaki, sedangkan sarcodina berasal dari kata
sarkodes : daging. Rhizopoda bergerak menggunakan kaki semu atau pseudopodia
yang berfungsi juga sebagai alat untuk menangkap mangsa. Pseudopodia merupakan
penjuluran dari sebagian protoplasma sel. Pada rhizopoda pseudopodia memiliki
beberapa bentuk seperti lobodia, filopodia, akropodia, dan rhizopodia.
Rhizopoda umumnya bersel satu dengan bentuk berubah-ubah.
Umumnya rhizopoda memiliki habitat di air tawar, air
laut, di tempat-tempat basah/lembap atau hidup sebagai parasit dalam tubuh
hewan dan manusia, makanannya diambil dengan cara fagosit dan dicerna di
vakuola makanan. Alat eksresi pada rhizopoda adalah vakuola kontraktil dan
pernapasan berlangsung di seluruh permukaan tubuh dengan cara difusi. Rhizopoda
berkembang biak dengan cara pembelahan biner.
Amoeba adalah salah satu
contoh dari rhizopoda, amoeba tidak mempunyai bentuk tubuh yang tetap dan
bergerak dengan menggunakan pseudopodia. Bagian luar tubuh amoeba terdapat
lapisan membran sel yang berfungsi sebagai pelindung isi sel, pengatur
pertukaran zat dan gas, dan penerima rangsang kimia.
Amoeba memiliki 2 lapisan sitoplasma yaitu ektoplasma
(bagian luar) dan endoplasma (bagian dalam). Berdasarkan tempat hidupnya ada
dua jenis amoeba yaitu ektoamoeba yang hidup di air laut, air tawar, dan tempat
basah, contoh: amoeba proteus, difflugia, dan globigerina. Sedangkan entamoeba
hidup di dalam organisme lain seperti entamoeba histolytica, entamoeba coli,
entamoeba gingivalis.
2) Filum Ciliata (Ciliophora)
Ciliata merupakan protista
bersel satu yang permukaan tubuhnya dipenuhi rambut atau bulu getar (silia)
yang berfungsi sebagai alat gerak dan untuk memasukan makanan ke dalam
sitoplasma, silia juga berfungsi sebagai penerima rangsang dari luar sel atau lingkungan.
Habitat ciliata banyak di tempat berair dan mengandung bahan organik, sebagian
ciliata hidup bersimbiosis dan lainnya sebagai parasit.
Sel ciliata mempunyai dua inti, yaitu makronukleus dan
mikronukleus, makronukleus berfungsi untuk pertumbuhan dan perkembangan
sedangkan mikronukleus berfungsi pada proses reproduksi. Reproduksi ciliata
secara aseksual adalah dengan pembelahan biner dan reproduksi seksual dengan
konjugasi, ciliata juga memiliki trikosis untuk pertahan diri. Contoh ciliata
adalah paramecium caudatum, stentor, didinum, dan vorticella.
3) Filum Zooflagellata (Zoomastigophora)
Zooflagellata mempunyai alat
gerak berupa bulu cambuk (flagela), sebagian besar hidup soliter dan sebagian
membentuk koloni. Ada zooflagellata yang hidup bersimbiosis dan ada yang
sebagai parasit dalam tubuh organisme lain.
Zooflagellata mempunyai bentuk tubuh tetap karena
dilindungi pelikel, habitatnya di air tawar, air laut, atau sebagai parasit di
tubuh organisme lain seperti hewan dan manusia. Reproduksinya ada dua cara
yaitu aseksual dengan pembelahan biner dan reproduksi seksual dengan cara
konjugasi. Contoh zooflagellata adalah leishmania donovani, trypanosoma
gambiense, trichomonas vaginalis, leishmania tropica.
4) Filum Sporozoa (apicomplexa)
Sporozoa berasal dari kata spora :
benih, dan zoon : binatang, bentuk tubuh umumnya bulat atau
bulat panjang. Pada umumnya sporozoa bersel satu dan tidak memiliki alat gerak,
dan hampir semuanya bersifat parasit.
Sporozoa dapat membentuk spora
pada fase zigot dan menginfeksi inangnya. Reproduksi dengan dua cara yaitu
aseksual (vegetatif) yang dibagi lagi menjadi schizogoni, yaitu pembelahan diri
yang berlangsung dalam tubuh inang, dan sporongoni, yaitu pembentukan spora
yang berlangsung di dalam tubuh inang perantaranya. Secara seksual (generatif)
disebut gamogoni (gametogenesis) yang berupa pembentukan dan peleburan sel-sel
gamet jantan dan betina yang terjadi di dalam tubuh inang perantara (hospes
intermediate).
Salah satu contoh sporozoa yaitu Plasmodium yang
bereproduksi secara metagenesis (pergiliran keturunan) yang terdiri dari dua
fase berikut:
a) Fase Generatif (Sporongoni)
Fase ini terjadi dalam tubuh
nyamuk sebagai inang perantaranya dimana nyamuk menghisap darah manusia yang
menderita malaria maka makrogametosit (betina) dan mikrogametosit (jantan) akan
ikut terhisap dan masuk ke dalam tubuh nyamuk, kemudian makrogametosit dan
mikrogametosit berkembang menjadi makrogamet dan mikrogamet dan selanjutnya
akan terjadi fertilisasi antara makrogamet (betina/ovum) dan mikrogamet
(jantan/sperma) dalam saluran pencernaan nyamuk, fertilisasi ini menghasilkan
zigot diploid (Ookinet), setelah itu ookinet membentuk kista dan dalam kista
zigot akan berkembang menjadi sporozoit yang selanjutnya akan menuju saluran
kelenjar ludah nyamuk.
b) Fase Vegetatif (Schizogoni).
Fase ini terjadi dalam tubuh
manusia ( inang tetap) alurnya yaitu sporozoit berpindah ke tubuh manusia
setelah digigit nyamuk anopheles betina, sporozoit kemudian menuju hati dan menetap
selama kurang lebih tiga hari dan berkembang menjadi merozoit, merozoit
menyerang sel-sel darah merah sehingga sel-sel tersebut pecah, dan dalam
keadaan ini manusia (penderita) mengalami demam malaria. Merozoit kemudian
berkembang menjadi gametosit (mikrogametosit dan makrogametosit).
Plasmodium terdiri dari empat
spesies yaitu :
i. Plasmodium vivax penyebab penyakit
malaria tertiana.
ii. Plasmodium malarie penyebab penyakit
malaria kuartana.
iii. Plasmodium ovale penyebab penyakit
malaria dengan gejala yang sama dengan malaria tertiana.
iv. Plasmodium falcifarium penyebab
penyakit malaria tropika.
5) Filum Foraminifera
Foraminifera memiliki cangkang
berwarna cerah dan pada permukaannya terdapat lubang kecil. Gerakan organisme
ini sangat lambat. Foraminifera hidup di laut dan menempel di bebatuan atau
sebagai plankton, cangkang foraminifera sering digunakan sebagai petunjuk
adanya kandungan minyak bumi dan gas alam. Contoh polistomella.
6) Filum Actinopoda
Actinopoda memiliki
pseudopodia yang ramping dan menyebar yang disebut axopodia dan umumnya
berbentuk seperti bola. Contoh spesies actinopoda adalah hellozoa, radiozoa.
2. Alga, Protista mirip tumbuhan.
a. Ciri-ciri Alga
Di alam Alga mempunyai ukuran
yang beranekaragam, mulai dari ukuran mikroskopis (hanya dapat diamati dengan
bantuan alat seperti mikroskop) seperti Euglena sp dan navicula, sampai yang
berukuran makroskopis (dapat dilhat tanpa bantuan alat) seperti laminaria dan
euchema. Alga bersifat eukariotik karena intinya mempunyai membran dan selnya
dikelilingi oleh dinding sel sehingga bentuknya bersifat tetap.
Alga terdiri dari alga
uniseluler (bersel satu) dan alga multiseluler (bersel banyak). Alga uniseluler
sebagian hidup soliter dan yang lain berkoloni, berbentuk bulat, oval, atau
seperti buah pir. Sedangkan alga multiseluler biasanya berupa lembaran atau
berbentuk benang. Alga biasanya terdapat di air (air tawar/air laut) dan di
tempat lembab dan basah.
Pada alga terdapat plastida
berupa kloroplas yang berfungsi menyerap energi cahaya matahari yang berguna
dalam proses fotosintesis sehingga alga dikatakan bersifat eukariotik atau
mampu membuat makanannya sendiri. Klorofil adalah pigmen yang terdapat pada
kloroplas, selain klorofil yang merupakan pigmen utama dalam proses
fotosintesis pada setiap jenis alga juga mempunyai pigmen tambahan yang berbeda
pada setiap jenis alga seperti karoten, fikobilin, xantofil, dan fukosantin.
Kandungan pigmen-pigmen inilah yang dijadikan sebagai dasar klasifikasi alga.
Pada bagian dalam atau
permukaan kloroplas terdapat struktur yang disebut pirenoid yang berfungsi
menyimpan cadangan makanan, terdapat berbagai jenis cadangan makanan yang
berbeda pada setiap jenis alga diantaranya paramilon, leukosin, laminarin dan
zat tepung.
Reproduksi alga berlansung
secara aseksual dan seksual. Reproduksi seksual pada alga terjadi dengan tiga
cara yaitu pembelahan biner, fragmentasi, dan pembentukan spora. Pembelahan
biner terjadi hanya pada alga uniseluler dimana sel induk alga membelah menjadi
2 bagian, kemudian masing-masing tumbuh menjadi alga baru, contohnya terjadi
pada Chlorella, Chlamydomonas, dan navicula. Sedangkan fragmentasi terjadi pada
alga multiseluler yang berbentuk benang atau lembaran dimana fragmentasi adalah
putusnya sebagian tubuh alga menjadi beberapa bagian dan akan tumbuh menjadi
individu-individu baru. Contohnya terjadi pada spirogyra dan volvox.
Pembentukan spora terjadi pada alga uniseluler maupun multiseluler, spora
dihasilkan dari pembelahan sel induk, dan setelah masak spora keluar dari
dinding induk dan tumbuh menjadi alga baru yang haploid.
Reproduksi seksual pada alga
berupa konjugasi yang terjadi pada alga multiseluler yang berbentuk benang atau
filamen. Sementara itu untuk alga uniseluler terjadi dengan penyatuan/peleburan
gamet yang berbeda jenis untuk menghasilkan zigot yang terjadi dengan
perantaraan air. Terdapat beberapa macam penyatuan gamet yaitu isogami,
anisogami, dan oogami. Isogami yaitu penyatuan gamet jantan dan betina dengan
bentuk dan ukuran sama. Anisogami adalah penyatuan gamet jantan dan betina yang
berbentuk sama tapi berbeda ukuran, sedangkan oogami yaitu penyatuan gamet
jantan dan betina yang berbeda bentuk maupun ukuran.
b. Klasifikasi Alga
Klasifikasi alga terutama
didasarkan pada pigmen dominan yang dikandungnya, selain itu beberapa faktor
penting lain seperti komponen penyusun dinding sel, struktur flagella, serta
jenis makanan cadangan juga ikut diperhatikan.
Alga dikelompokkan dalam tujuh filum yaitu
euglenophyta, chlorophyta, chrysophyta, phaeophyta, bacillariophyta (diatom),
rhodophyta, dan pyrrophyta (alga api).
1) Filum Euglenophyta
Euglenophyta adalah organisme
uniseluler menunjukan ciri mirip tumbuhan sekaligus seperti hewan, dikatakan
mirip tumbuhan karena mempunyai klorofil untuk melangsungkan proses
fotosintesis, selain klorofil euglenophyta juga mempunyai pigmen lain seperti
karotenoid dan xantofil. Euglenophyta dikatakan mirip hewan karena selnya tidak
mempunyai dinding sel, bergerak bebas juga terdapat bintik mata. Tidak adanya
dinding sel pada euglenophyta digantikan oleh selaput protein (pelikel) yang
lentur, sedangkan bintik mata pada euglenophyta berisi fotoreseptor menyebabkan
pergerakannya menuju cahaya.
Euglenophyta mempunyai habitat
di air tawar, air tanah, dan tempat-tempat lembab dan banyak ditemukan di sawah
atau air yang menggenang, cadangan makanan pada euglenophyta adalah paramilon
(sejenis zat pati). Contoh organisme euglenophyta adalah euglena sp.
Euglena sp berbentuk oval memanjang dan di salah satu
ujungnya terdapat mulut sel dan bergerak menggunakan flagella. Reproduksi
euglena sp dengan cara pembelahan biner.
2) Filum Chlorophyta (ganggang hijau)
Chlorophyta sebagian besar
hidup di habitat air tawar (90 persen), dan dilaut (10 persen) yaitu jenis yang
berukuran besar, ada yang bersifat uniseluler dan ada pula yang multiseluler.
Pigmen dominan pada chlorophyta adalah klorofil a dan b, selain itu juga
terdapat pigmen lain yaitu karoteniod yang menyebabkan tubuhnya berwarna hijau.
Selain itu dinding selnya tersusun atas bahan selulosa, dan memiliki cadangan
makanan berupa amilum yang dihasilkan dan disimpan di pirenoid.
Chlorophyta bereproduksi secara seksual dan aseksual,
secara seksual dengan cara konjugasi yaitu isogami atau anisogami. Sedangkan
reproduksi aseksual dengan cara pembelahan biner, fragmentasi, dan pembentukan
zoospora. Beberapa contoh spesies chlorophyta adalah chlorella, chlamydomonas,
volvox globator, spirogyra, hidrodictyon, chroococcus, ulva, chara, oedogonium.
a) Chlorella
Merupakan organisme uniseluler
yang berbentuk bulat dan mempunyai kloroplas seperti mangkuk. Chlorella
memiliki habitat di air tawar, air laut dan tempat lembab. Reproduksinya secara
aseksual yaitu dengan pembelahan sel. Chlorella mengandung protein tinggi dan
dapat dimanfaatkan sebagai bahan obat-obatan, kosmestik, dan bahan makanan.
b) Chlamydomonas
Berbentuk bulat telur dan
memiliki dua flagella dan kloroplasnya berbentuk seperti mangkuk. Selain itu
terdapat juga stigma (bintik mata) dan pirenoid sebagai tempat pembentukan dan
penyimpanan zat tepung serta terdapat 2 vakuola kontraktil. Cara repoduksi
seksual dengan cara konjugasi sedang reproduksi aseksualnya dengan cara
membentuk zoospora.
c) Volvox globator
Volvox banyak ditemukan di air
tawar dan hidup berkoloni dan berbentuk bola, volvox bergerak menggunakan
flagella dan mempunyai bintik mata. Reproduksi seksualnya secara konjugasi dan
aseksual dengan cara fragmentasi.
d) Spirogyra
Selnya berbentuk seperti
benang serta kloroplasnya berbentuk spiral. Spirogyra memiliki habitat di air
tawar yang jernih dan tenang. Spirogyra juga memiliki pirenoid dan reproduksi
seksualnya dengan cara konjugasi dan aseksual secara dengan cara fragmentasi.
e) Hidrodictyon
Hidrodictyon hidup berkoloni
membentuk jala dan banyak ditemukan di air tawar. Reproduksi seksualnya dengan
cara konjugasi dan aseksual dengan melakukan fragmentasi.
f) Chrococcus
Merupakan organisme uniselular
yang tidak mempunyai alat gerak dan memiliki habitat di air tawar. Bereproduksi
secara seksual dengan cara konjugasi dan aseksual dengan membentuk zoospora.
g) Ulva lactuca
Ulva memiliki habitat di dasar
perairan laut yang dangkal, berbentuk seperti lembaran daun, daur hidupnya
mengalami metagenesis. Reproduksi seksualnya dengan cara konjugasi sedangkan
reproduksi aseksualnya dengan cara membentuk zoospora, ulva memiliki manfaat sebagai
bahan makanan (selada laut).
h) Chara
Chara memiliki habitat di air
tawar dan menyerupai tumbuhan tingkat tinggi yaitu mempunyai struktur berbentuk
menyerupai batang beruas-ruas dan memiliki cabang, pada ruas tubuh terdapat
nukula yang mengandung arkegonium yang menghasilkan ovum serta globula yang
mengandung anteridium penghasil spermatozoid, peleburan ovum dan spermatozoid
menghasilkan zigospora yang akan menjadi individu baru.
i) Oedogonium
Memiliki habitat di air tawar.
Reproduksi seksualnya yaitu dengan cara fertilisasi ovum oleh spermatozoid,
sedangkan reproduksi aseksualnya dengan membentuk zoospora.
3) Filum Chrysophyta
Chrysophyta sebagian bersifat
uniseluler (bersel satu) dan sebagian bersifat multiseluler (bersel banyak),
kebanyakan sebagai fitoplankton di ekosistem perairan. Habitatnya sebagian
besar berada di air tawar dan laut, pigmen utama pada chrysophyta adalah klorofil,
selain itu terdapat pigmen karotenoid dan xantofil sehingga menyebabkan
tubuhnya berwarna coklat keemasan.
Sebagian Chrysophyta memiliki
flagela untuk membantu pergerakan. Reproduksi seksual chrysophyta dengan cara
peleburan sperma dan ovum sehingga menghasilkan zigot sedangkan reproduksi
aseksual dengan pembelahan biner atau pembentukan zoospora pada organisme
uniseluler dan multiseluler. Beberapa contoh organisme chrysophyta adalah
ochromonas (uniseluler), vaucheria (multiseluler), dan synura.
a) Ochromonas
Terdapat kloroplas yang
melengkung. Ochromonas berbentuk bola dan memiliki alat gerak berupa 2 flagela.
b) Vaucheria
Habitatnya berada di air tawar
dan payau, berbentuk benang yang tak bersekat. Reproduksi seksualnya adalah secara
oogonium dengan menggunakan anteridium, sedangkan reproduksi aseksual dengan
membentuk zoospora.
4) Filum Phaeophyta
Phaeophyta adalah organisme
multiseluler yang menyerupai tumbuhan tingkat tinggi karena mempunyai struktur
seperti akar, batang dan daun. Phaeophyta memiliki tubuh berwarna kecoklatan
karena mengandung pigmen fukosantin selain dari pigmen utama yaitu klorifil a
dan c. phaeophyta sebagian besar hidup di perairan dengan talus yang terapung
di permukaan, dinding selnya mengandung selulosa dan algin (asam alginat) dan
memiliki cadangan makanan berupa laminarin yang disimpan dalam pirenoid.
Reproduksi seksual phaeophyta
dengan peleburan sel gamet, sedangkan secara aseksual dengan cara membentuk
zoospora. Salah satu contoh spesies phaeophyta adalah laminaria, laminaria
menghasilkan asam alginat sebagai bahan pembuat gel untuk industri makanan,
pakaian dan kosmestik. Contoh lain phaeophyta adalah Fucus, macrocystis,
ascophylum, sargassum, dan turbinaria.
5) Filum Bacillariophyta (Diatom)
Bacillariophyta adalah
organisme uniseluler yang memiliki habitat di laut dan air tawar dan sebagian
berperan sebagai phytoplankton. Pada dinding selnya mempunyai dua struktur
yaitu belahan kotak (hipoteka) dan tutup (epiteka). Pigmen yang dikandungnya
adalah klorofil a dan c, serta karotenoid dan xantofil. Pada dinding sel
tersusun dari bahan silikat hidrat (zat kersik), dan memiliki cadangan makanan
berupa amilum. Contoh organisme bacillariophyta adalah navicula, pinnularia,
dan dermidium.
6) Filum Rhodophyta
Merupakan organisme
multiseluler dengan bentuk tubuh seperti rumput dan sering disebut rumput laut
(sea weed), habitatnya sebagian besar hidup di laut, dan sisanya hidup di air
tawar. Pigmen yang dikandungnya adalah klorofil a dan b, karotenoid dan
fikobilin sehingga tubuhnya berwarna merah. Cadangan makanannya berupa zat
tepung florid dan dinding selnya terdiri atas selulosa dan pectin.
Reproduksi seksual pada
rhodophyta adalah adalah secara oogami sedangkan secara aseksual dengan
membentuk spora. Contoh organisme rhodophyta adalah euchema spinosum, gelidium
pusillum, palmaria palmate, gracillaria verrucosa.
7) Filum Pyrrophyta (Alga api)
Pyrrophyta sering juga disebut
dinoflagelata dan mempunyai ciri uniseluler dan bergerak aktif, sebagian besar
hidup di laut dan yang lain di air tawar. Pigmen yang dikandungnya adalah
klorofil a dan c, karotenoid, dan xantofil. Reproduksinya secara aseksual yaitu
dengan cara membelah diri. Beberapa jenis pyrrophyta seperti nocticula mampu berpendar
(fluoresen) di laut sehingga tampak bercahaya pada malam hari dan jumlahnya
melimpah sehingga membentuk red tide, yaitu air laut yang tampak berwarna merah
kecoklatan.
Beberapa spesies pyrrophyta
dapat menghasilkan racun (toksin) yang dapat membunuh hewan laut yang berada
disekitarnya seperti Gymnodinium breve, dan gonyaulax. Dinding selnya berupa
selulosa submembran dan memiliki 2 flagela, sedangkan cadangan makanannya
berupa amilum.
3. Protista Mirip jamur
a. Ciri-ciri Protista mirip jamur
Protista yang menyerupai jamur
tidak dimasukkan dalam klasifikasi jamur karena mempunyai struktur tubuh dan
cara reproduksi yang tidak sama dengan kelompok jamur biasa. Pada jamur lendir,
reproduksinya mirip fungi tapi pada fase vegetatifnya menyerupai amoeba,
sedangkan pada jamur air (Oomycota) struktur selnya lebih menyerupai alga
dibanding fungi. Protista mirip jamur ada yang bersifat uniseluler dan ada yang
bersifat multiseluler selain itu juga tidak memiliki klorofil.
b. Klasifikasi Protista mirip jamur
Protista mirip jamur dibagi
dalam 3 filum yaitu Oomycota (Jamur Air), Myxomycota ( Jamur Lendir
Plasmodial), dan Acrasiomycota (Jamur Lendir Bersel).
1) Filum Oomycota (Jamur Air)
Jamur Air mempunyai habitat di
tempat lembap dan berair. Selnya mempunyai banyak inti yang terdapat didalam
benang-benang hifa yang tidak bersekat sedangkan dindingnya terdiri dari
selulosa.
Jamur Air sebagian bersifat
saprofit dan sebagian bersifat parasit. Reproduksi seksualnya yaitu dengan cara
fertilisasi yang membentuk zigot yang kemudian berkembang menjadi oospora,
oospora ini dilengkapi dengan alat gerak berupa 2 buah flagela. Contoh Oomycota
adalah Saprolegnia sp, Phytophthora sp, pythium sp.
2) Filum Myxomycota ( Jamur Lendir
Plasmodial)
Myxomycota dapat ditemukan di
hutan basah, batang kayu yang busuk, tanah lembap,dan tempat-tempat lembap
lainnya. Myxomycota sebagian besar memiliki tubuh yang berwarna cerah misalnya
kuning atau oranye. Myxomycota tidak memiliki klorofil, dan struktur molekul
membran sel jamur mirip alga. Struktur tubuh vegetatifnya berbentuk seperti
lendir dan sifat pada fase vegetatifnya mirip amoeba, sedangkan cara
reproduksinya mirip fungi.
Reproduksi seksual Myxomycota
adalah dengan cara singami dan reproduksi aseksualnya dengan cara membentuk
spora. Contoh Acrysia, lycogala, dan physarium.
3) Filum Acrasiomycota (Jamur Lendir
Bersel)
Acrasiomycota memiliki habitat
di air tawar, tanah lembap, dan tempat-tempat berair lainnya. Acrasiomycota
bergerak dengan menggunakan kaki semu yang juga berguna untuk memfagosit
bakteri dan mikroorganisme lainnya.
