ch 25

What is thought to be the correct sequence of these events, from earliest to most recent, in the evolution of life on Earth? 1. origin of mitochondria 2. origin of multicellular eukaryotes 3. origin of chloroplasts 4. origin of cyanobacteria 5. origin of fungal-plant symbioses

4,1,3,2,5

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 construct 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.

A

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.

A

The oldest fossil eukaryote that can be resolved taxonomically is of A) a red alga that lived 1.2 billion years ago. B) a red alga that lived 635 million years ago. C) a fungus that lived 2 billion years ago. D) a fungus that lived 550 million years ago. E) an Ediacaran that lived 550 million years ago.

A

Which of the following statements concerning protists is true? A) All protists have mitochondria, although 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.

A

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.

A

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.

A

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.

B

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.

B

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

B

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.

C

Which group is incorrectly paired with its description? A) rhizarians—morphologically diverse group that includes amoebas with threadlike pseudopodia B) diatoms—important producers in aquatic communities C) red algae—acquired plastids by secondary endosymbiosis D) apicomplexans—parasites with intricate life cycles E) diplomonads—protists with modified mitochondria

C

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.

D

Which of the following is correctly described as a primary producer? A) oomycete B) kinetoplastid C) apicomplexan D) diatom E) radiolarian

D

The evolution of complex multicellularity in eukaryotes A) occurred only once, in the common ancestor of all eukaryotes. B) occurred only once, in the common ancestor of all multicellular eukaryotes. C) occurred only once, in the animal lineage. D) is not documented by the fossil record. E) occurred independently in several different eukaryotic lineages.

E

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

a

In a sample of pond water, a new organism is identified with the following characteristics: It consists of 70 cells surrounded by rigid cell walls, which join the cells together. Inside each of these identical cells are mitochondria and chloroplasts. Such an organism would most likely be classified as a A) colonial photosynthetic eukaryote. B) fungal photosynthetic eukaryote. C) colonial photosynthetic prokaryote. D) multicellular photosynthetic prokaryote. E) colonial eukaryotic fungus.

a

Reinforced, threadlike pseudopods that can perform phagocytosis are generally characteristic of which group(s)? A) radiolarians and forams B) gymnamoebas C) entamoebas D) amoeboid stage of cellular slime molds E) oomycetes

a

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

a

The evolution of multicellularity in animals has primarily occurred by the A) remodeling of old genes. B) deletion of many old genes. C) production of many new genes. D) deletion of many old chromosomes. E) fusion of genes from many ancestral organisms.

a

Which of the following is the most likely sequence of events, from earliest to most recent, in the evolution of sponges (organisms with many cells that have different functions)? 1) single-celled eukaryote 2) single-celled prokaryote 3) multicellular eukaryote 4) colonial eukaryote A) 2, 1, 4, 3 B) 2, 1, 3, 4 C) 1, 2, 3, 4 D) 1, 2, 4, 3

a

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.

a

A snail-like, coiled, porous test (shell) of calcium carbonate is characteristic of which group? A) diatoms B) foraminiferans C) radiolarians D) gymnamoebas

b

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

b

All protists are A) unicellular. B) eukaryotic. C) symbionts. D) monophyletic. E) mixotrophic.

b

Biologists think 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.

b

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

b

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

c

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?

c

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.

c

Multicellular colonies of plant cells adhere to each other primarily by ________, whereas multicellular colonies of animal cells are typically held together by ________. A) fusion of cellular membranes; cell walls B) cell walls; fused cellular membranes C) cell walls; proteins D) interlocking chloroplasts; interlocking mitochondria E) interlocking cellular shapes (like puzzle pieces); large, calcified capsules

c

The evolution of multicellularity in animals required adaptations that promoted A) cellular migration and intercellular communication. B) cellular migration and cellular adhesion. C) cellular adhesion and intercellular communication. D) photosynthesis and cellular migration. E) cellular fusion and regeneration.

c

Why is the filamentous morphology of the water molds considered a case of convergent evolution with fungi? 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.

c

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

d

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

d

The last common ancestor of fungi and animals was most likely a A) colonial photosynthetic eukaryote. B) multicellular photosynthetic eukaryote. C) colonial photosynthetic prokaryote. D) multicellular photosynthetic prokaryote. E) single-celled eukaryote.

e

Which of the following are actual mutualistic partnerships that involve a protist and a host organism? A) cellulose-digesting gut protists—wood-eating termites B) dinoflagellates—reef-building coral animals C) Trichomonas—humans D) algae—certain foraminiferans E) all except that involving humans

e

the chloroplasts of all of the following are thought to be derived from ancestral red algae, except those of

green algae

which of these observations gives the most support to the endosymbiotic theory for the origin of eukaryotic cells

the similarity in size between the cytosolic ribosomes of prokaryotes and the ribosomes within mitochondria and chloroplasts