Exam 1 Review Questions
1. (Ch 24) Which characteristic is not a requirement for metabolic activity seen in the Archaea
that enable them to live in hydrothermal vents, acidic or salty water, and the rumens of cows?
A. acid tolerance
B. temperature preference
Answer: C. presence of oxygen
D. methane production
E. salt tolerance
2. (ch 24) It has been suggested that cyanobacteria are the most important organisms to have
evolved on the Earth. What evidence justifies this view?
A.
Cyanobacteria form microbial mats, enabling them to spread across lake bottoms and
shallow seafloors.
B.
Some cyanobacteria can fix nitrogen, which plants need in order to produce oxygen,
making them unique among bacteria.
C.
Some cyanobacteria differentiate to form multiple cell types, making them the ancestors
of plants and animals.
Answer: D. Cyanobacteria evolved the ability to use water as an electron donor in
photosynthesis, generating the oxygen gas found in the atmosphere.
3. (Ch 24) A researcher discovers a new unicellular organism that contains a single circular
chromosome and no membrane-bound organelles. Upon closer observation, the researcher
notices that this organism can also fix nitrogen and produce methane. How should this organism
be classified? Answer: A. as an archaeon
B. as a bacterium
C. as a eukaryote
4. (Ch 24) A researcher synthesizes a new drug that specifically targets and degrades
peptidoglycan. What type of infections could this drug treat?
Answer: A. infection caused by bacteria
B. infection caused by archaeons
C. infection caused by viruses
D. infection caused by eukaryotes
5. (Ch 25) Phagocytosis provides a means by which heterotrophic protists can take in food
particles. In what way do photosynthetic protists reflect phagotrophy?
A. Photosynthetic protists do not reflect phagotrophy, as these cells fix carbon dioxide into
sugars and do not require particulate matter as a source of carbon.
Answer: B. Phagotrophy is the process by which cyanobacteria were introduced into protistan
cells to become endosymbionts and, eventually, chloroplasts.
C.
Evolutionary loss of the ability to take in particles by phagotrophy forced some protists to
evolve a capacity for photosynthesis.
D.
Phagotrophy introduces carbon dioxide into the cells of photosynthetic algae, where it
isreduced to form sugars.
6. (Ch 25) Chloroplasts have an outer and an inner membrane that separate the stroma and
thylakoid membrane from the cytoplasm. What is believed to be the origin of the outer
membrane of the chloroplast?
Answer: A. It is the remnant of the ancient host cell's plasma membrane, following endocytosis
of the cyanobacterium.
B.
It is a nonfunctional remnant resulting from the amplification of the inner membrane of
the chloroplast to increase its surface area.
C.
It is an adaptation of the symbiotic cyanobacteria to protect it from fusing with lysosomes
present in the cytoplasm of the ancient “host” cell.
7. (Ch 25) Among eukaryotes, some multicellular organisms lack both chloroplasts and
mitochondria.
Answer: A. true
B. false
8. (Ch 25) Which organism is your closest relative?
A. a slime mold
B. an apple tree
Answer: C. a mushroom
D. the malaria parasite
9. (Ch 26) Why is bulk flow a necessary condition of complex multicellularity?
A. Complex multicellularity reflects cell adhesion between cells, and this cannot happen without
bulk flow of signaling molecules from the environment.
Answer: B. Organisms exhibiting complex multicellularity are large and have cells/tissues that
are not in contact with their environment. Systems that can overcome the limits of diffusion must
evolve for basic physiologic processes to occur.
C.
Bulk flow is necessary to move large amounts of liquid through the organism, depending
on physiologic needs. The tissues can all receive necessary nutrients from the environment, but
bulk flow speeds the rate of diffusion.
D.
Complex multicellularity is related to the increase in oxygen in the environment. Because
bulk flow systems are only related to the delivery of oxygen to tissues, higher environmental
oxygen selected for individuals with bulk flow systems.
10. (Ch 26) What properties of oxygen make it a critical environmental requirement for
multicellularity? Select all that apply.
Answer: A. Oxidation by O2 can provide a large amount of
energy. B. Oxygen does not easily diffuse.
C. Oxygen is present at low levels at the ocean floor.
Answer: D. Oxygen is a gas.
11. (Ch 26) What is a possible mechanism for the immense diversity observed in complex
multicellular organisms? Select all that apply.
Answer: A. mutations in regulatory genes
B. mutations in essential genes
Answer: C. interactions with the environment
D. a lack of cell walls
12. (Ch 26) The early evolution of land plants occurred in moist lowland habitats until about 400
million years ago, when they moved to the interiors of continents. Which of the characteristics
likely contributed to the colonization of continental regions further from standing water?
A. absorption of water through diffusion on photosynthetic tissue
B. ability to perform photosynthesis
Answer: C. development of vascular tissue for bulk flow
D. cell-cell adhesion, which provides structural support for multicellularity
13. (Ch 32) How do the two species that make up a lichen benefit from their symbiotic
association? Select all that apply.
A. The fungi receive carbohydrates from the algae, while the algae receive nitrogen from the
fungi.
Answer: B. Both partners are able to grow on substrates on which each would be unable to
grow on its own.
C. The algae receive carbon as a result of the fungi's ability to degrade lignin and cellulose,
while the fungi receive nitrogen from the algae.
Answer: D. The fungi receive carbohydrates and, in some cases, nitrogen from the algae, while
the algae gain a “home” that anchors them on the substrate.
14. (Ch 32) Fungi that live on dead and decaying material are essential to life on Earth because
they:
A. grow in mycorrhizal association with the roots of most plants, providing minerals to the plants.
Answer: B. speed the recycling of nutrients.
C. help to digest sap in phloem of dead and dying trees.
D. recycle inorganic compounds into organic compounds.
E. respire like plants, taking in carbon dioxide and decreasing greenhouse gases.
15. (Ch 32) Many antibiotics work by inhibiting the synthesis of peptidoglycan, a component of
the bacterial cell wall. What is a possible mechanism of action for antifungal drugs?
A. inhibiting the synthesis of peptidoglycan in fungi
B. inhibiting the synthesis of cellulose in fungi
Answer: C. inhibiting the synthesis of chitin in fungi
D. inhibiting the synthesis of lignin in fungi
16. (Ch 32) Imagine that fungal hyphae were as thick as a human hair. How might this
increased thickness affect the ecological role of fungi?
Answer: A. Decomposition rates of dead organisms would decrease because the fungi's ratio of
surface area to volume would decrease.
B. Decomposition rates of dead organisms would increase because the fungi's ratio of surface
area to volume would increase.
C. There would be no effect on the rates of decomposition of dead organisms.