Chapter 29 Review

Protists have a range of nutritional strategies

Protists include phototrophs, heterotrophs, (phagotrophs or osmotrophs), and mixotrophs capable of both modes.

Protists have several means of locomotion.

Protists mainly use flagella or pseudopods for locomotion, although many other means of propulsion are found.

The nucleus and endoplasmic reticulum arose from membrane infoldings. Mitochondria evolved engulfed aerobic bacteria.

According to the theory of endosymbiosis, ancestral eukaryotic cells engulfed aerobic bacteria, which then became mitochondria.

Fossil evidence dates the origins of eukaryotes

Although eukaryotes may have arisen earlier, the fossil evidence of their appearance dates back to 1.5 BYA

Apicomplexans include the malaria parasite.

Apicomplexans are spore-forming animal parasites. They have a unique arrangement of organelles at one end of the cell, called the apical complex, which is used to invade the host.

Brown algae include large seaweeds.

Brown algae are typically large seaweeds that have a haplodiplontic life cycle, producing gametophyte and sporophyte stages.

Cellular slime molds exhibit cell differentiation.

Cellular slime molds such as Dictyostelium discoideum can signal and interact with neighboring cells, resulting in differentiated cell types in an aggregate organism.

Chloroplasts evolved from engulfed photosynthesis bacteria.

Chloroplasts are believed to have arisen when ancestral eukaryotic cells engulfed photosynthetic bacteria. Brown algae arose through a secondary endosymbiotic event when a red alga was engulfed by a single-celled organism.

Ciliates are characterized by their mode of locomotion.

Ciliates are unicellular, heterotrophic protists that use numerous cilia for feeding and propulsion. Each cell has a macronucleus and a micronucleus. Micronuclei are exchanged during conjugation.

Propulsion via a Single Posterior Flagellum in Opisthokonta

Colonial choanoflagellates are structurally similar to freshwater sponges, and molecular similarities have been found.

Protists are the bridge to multicellularity.

Colonial protists may be the precursos of multicellular organisms.

Diatoms are unicellular organisms with double shells.

Diatoms have silica in their cell walls. Each diatom produces two overlapping glassy shells that fit like a box and lid.

Dinoflagellates are photosynthesizers with distinctive features.

Dinoflagellates have pairs of flagella arranged so that they swim with a spinning motion. Blooms of dinoflagellates cause red tides.

Diplomonads lack function mitochondria.

Diplomonads are unicellular, move with flagella, and have 2 nuclei.

Protists cell surfaces vary widely.

Extracellular material (ECM) may cover the plasma membrane.

Euglenozoans change shape while swimming.

Free-living euglenids, exemplified by Euglena, can produce chloroplasts to carry out photosynthesis in the light. They contain a pellicle and move via anterior flagella. Kinetoplastids are parasitic and are distinctive in having a single, unique mitochondrion with two types of circular DNA.

Radiolarians have silica exoskeletons.

Glassy exoskeletons made of silicia give radiolarians a distinct shape. Microtubules support pseudopods that extrude toward the tips of the spiky exoskeleton.

Endosymbiosis is supported by a range of evidence.

In support of endosymbiosis, several organelles are found to contain their own DNA, which closely resembles that of prokaryotes. Over a billion and a half years, many of the chloroplast and mitochondrial genes have migrated to the nuclear genome.

Cercozoa locomote with flagella or pseudopods.

Like the marine radiolarians, cercozoans have silica exoskeletons, but most are found in soils. Cercozoans ingest green algae and may provide clues to the evolution of endosymbiosis.

Most amoeba are free-living, but some are parasitic.

Many protists are free-living and found in the soil and freshwater ecosystems, but a few species are pathogenic to humans

Mitosis evolved in eukaryotes.

Mechanisms of mitosis vary among organisms, suggesting that the process did not evolve all at once.

Eukaryotes are organized into 6 supergroups that all contain protists.

Molecular systematics is helping to sort out the protists, which are now grouped into 6 supergroups: Excavata, Chromalveolata, Archaeplastida, Rhizaria, Amoebozoa, and Ophisthokonta. With the exception of Chromalveolata, the supergoups are monophyletic. Monophyletic clades have been indentified among the protists.

Oomycetes, the "water molds", have some pathogenic members.

Oomycetes are parasitic and are unique in the production of asexual spores (zoospores) that bear two unequal flagella.

Parabasalids have undulating membranes.

Parabasalids use flagella and undulating membranes for locomotion.

Plasmodial slime molds are multinucleate.

Plasmodia in their feeding phase are macroscopically visible masses of oozing slime. These colorful large cells undergo repeated rounds of mitosis without cell division.

Protists reproduce asexually and sexually.

Protists can reproduce asexually by mitosis, budding, or schizogony. They may also carry out sexual reproduction.

Rhodophyta are red algae.

Red algae produce accessory pigments that may give them a red color. They lack centrioles and flagella, and they reproduce using an alternation of generations.

Foraminifera fossils created huge limestone deposits.

The Foraminifera are heterotrophic marine protists with pore-studded shells primarily formed by deposit of calcium carbonate

Chlorophytes and carophytes are green algae.

Unicellular chlorophytes include Chlamydomonas, which has two flagella, and Chlorella, which has no flagella and reproduces asexually. Volvox is an example of a colonial green alga; some cells are specialized for producing gamets or for asexual reproduction. It may represent a step on the way to multicellularity. Multicellular chlorophytes can have haplodiplontic life cycles. Ulva has sporophyte and gametophyte generations; however, the chlorophytes didn't give rise to land plants although they are the closest relatives to land plants. Both groups within the charophytes, Charales and Coleochaetales, have plasmodesmata, cytoplasmic links between cells. They also undergo mitosis and cytokinesis like terrestrial plants. Charophytes are most closely related to the land plants of all the algae.

When food is scarce, cells of this organism communicate with each other to form a multicellular slug. a. Cellular slime molds b. True amoebas c. Foraminifera d. Diatoms

a. Cellular slime molds

Examine the life cycle of cellular slime molds, and determine which feature affords the greatest advantage for surviving food shortages. a. Cellular slime molds produce spores when starved b. Cellular slime molds are saprobes c. A diet of bacteria ensures there will never be a shortage of food d. Cellular slime molds use cAMP to guide each other to food sources.

a. Cellular slime molds produce spores when starved

Choose all of the following that are photosynthetic: a. Diatoms b. Ciliates c. Apicomplexans d. Dinoflagellates

a. Diatoms d. Dinoflagellates

DNA is not found in this organelle: a. Endoplasmic reticulum b. Nucleus c. Chloroplast d. Mitochondrion

a. Endoplasmic reticulum

Determine which feature of the choanoflagellates was likely the most significant for the evolution of animals? a. Flagellum with a funnel-shaped, contractile collar also found in sponges b. A tyrosine kinase receptor on the surface of choanoflagellates that has strong homology to fungi c. A colonial form that resembles some fungi d. Eyespots that are similar to ribbon worms

a. Flagellum with a funnel-shaped, contractile collar also found in sponges

If a cell contains a pellicle, it: a. can change shape readily b. is shaped like a sphere c. is shaped like a torpedo d. must have a contractile vacuole

a. can change shape readily

Fossil evidence of eukaryotes dates back to: a. 2.5 BYA b. 1.5 BYA c. 2.5 MYA d. 1.5 MYA

b. 1.5 BYA

Choose all of the following that exhibit an alternation of multicellular generations: a. dinoflagellates b. brown algae c. red algae d. diatoms

b. brown algae c. red algae

The function of apical complex in apicomplexans is to: a. propel the cell through water b. penetrate host tissue c. absorb food d. detect light

b. penetrate host tissue

The products of budding are: a. two cells of equal size b. two cells, one of which is smaller than the other. c. many cells of equal size d. many cells of variable size

b. two cells, one of which is smaller than the other

Both diplomonads and parabasalids: a. contain chloroplasts b. lack mitochondria c. have multinucleate cells d. have silica in their cell walls

c. have multinucleate cells

Stramenopila are: a. tiny flagella b. large cilia c. small hairs on flagella d. pairs of large flagella

c. small hairs on flagella

Analyze the following statements and choose the one that most accurately supports the endosymbiotic theory: a. Mitochondria rely on mitosis for replication b. Chloroplasts contain DNA but translation does not occur in chloroplasts c. Vacuoles have double membranes d. Antibiotics that inhibit protein synthesis in bacteria can have the same effect on mitochondria

d. Antibiotics that inhibit protein synthesis in bacteria have the same effect on mitochondria

Which is most likely the ancestor of animals? a. Trypanosomes b. Diplomonads c. Ciliates d. Choanoflagellates

d. Choanoflagellates

Trypanosomes are examples of: a. euglenoids b. diplomonads c. parabasalids d. kinetoplastids

d. kinetoplastids