Problem 1. Which of the following statements regarding extremophiles is FALSE? a

Question

Problem 1. Which of the following statements regarding extremophiles is FALSE?

a. All extremophiles are in the Archaea domain.

b. All Archaea are considered extremophiles.

c. Extremophiles can survive without oxygen.

d. Extremophiles are similar to types of bacteria.

e. Extremophiles may have been some of the earliest living organisms on Earth.

Problem 2. Humans belong to the domain Eukarya; therefore, humans are more closely related to _______ than _______.

a. Extremia; Archaea

b. Archaea; Extremia

c. Bacteria; Archaea

d. Archaea; Bacteria

e. Humans aren't more closely related to any one of these than to any one of the other.

Problem 3. Prokaryotes lack which of the following organelles?

a. nucleus

b. mitochondria

c. endoplasmic reticulum

d. b and c

e. a, b, and c

Problem 4. Which of the following is/are a primary difference(s) between all prokaryotes and eukaryotic cells?

a. Prokaryotes have DNA that floats freely in the cytoplasm.

b. Prokaryotes are significantly smaller than eukaryotic cells.

c. Prokaryotes do not have ribosomes like eukaryotic cells.

d. a and b

e. a, b, and c

Problem 5. Cyanobacteria are _______ because they contain the ability to conduct the specialized function of photosynthesis.

a. autotrophic

b. chemotrophic

c. heterotrophic

d. exotrophic

e. intratrophic

Problem 6. Heterotrophic prokaryotes are associated with important ecological functions such as _____________.

a. nitrogen fixation

b. oil spill cleanup

c. degradation of landfill contents

d. b and c

e. a, b, and c

Problem 7. Which of the following statements regarding bacteria is/are TRUE?

a. Bacteria are essential to life on Earth.

b. Certain bacteria obtain their energy from inorganic gases.

c. Bacteria often have a symbiotic relationship with other organisms.

d. a and b

e. a, b, and c

Problem 8. You have just identified an Archaea species that lives on the scales of a deep-water fish. You find that when you have a pure culture of the new species, it will not survive. Which of the following could explain the inability to replicate the natural environment of the bacteria?

a. The culture on the scales is being kept at high pressure.

b. The new species requires a symbiotic relationship with other organisms on the scales that is not being replicated.

c. The culture is not being kept at high temperatures.

d. The new species requires an aerobic environment.

e. all of the above

Problem 9. Abiotic synthesis of organic molecules requires _______.

a. hydrogen

b. methanogenesis

c. serpentinization

d. anaerobic Archaea

e. all of the above.

Problem 10. Why is it hard for scientists to study hyperthermophil behavior in the laboratory?

a. Hyperthermophils can survive only at very high temperatures that are difficult to replicate in a lab setting.

b. Hyperthermophils are physically identical to bacteria, making it hard to identify in a lab setting.

c. Hyperthermophils have a short life cycle, which makes it hard to study one particular organism.

d. Hyperthermophils can survive only at very low temperatures, which are difficult to replicate in a lab setting.

e. none of the above

Explanation / Answer

Answers to the given multiple choice questions.

1) (b)  All Archaea are considered extremophiles.

Explanation: All archaea are not extremophiles. Though they are most abundantly found in extreme environments like hot springs and salt lakes, but they have also been isolated from a wide range of habitats including oceans, soil and marshlands.

2) (d) Archaea, Bacteria

Explanation: Although archaea and bacteria both are single-celled organisms and are classified as prokaryotes, humans are more closely related to archaea. It is believed that eukaryotic cells evolved from archaea and there has been found genetic similarity among them.

3) (e) a, b and c

Explanation: Bacteria are unicellular prokaryotic organisms, which lack any membrane-bound organelles like eukaryotic cells.

4) (d) a and b

Explanation: Bacteria do not have a well-defined nucleus like eukaryotes. The genetic material or DNA in bacteria floats freely in the cytoplasm. But ribosomes are present both in bacteria and eukaryotic cells.

5) (a) Autotrophic

Explanation: Organisms which are able to synthesize their own food by the process of photosynthesis are known as autotrophs. Cyanobacteria also are known as blue-green algae possess photosynthetic pigments.

6) (d) b and c

Explanation: Heterotrophic prokaryotes utilize organic compounds such as oil and landfill components to obtain food and energy. Hence they are useful in clearing of oil spills and degrading landfill.

7) (e) a, b and c

Explanations: All the statements regarding bacteria are true.

8) (b) The new species requires a symbiotic relationship with other organisms on the scales that is not being replicated.

Explanation: Symbiotic relationships exist in nature and are essential for the survival of the participating organisms. When the organisms are isolated they might not survive in a replicated environment.

9) (e) All of the above.

Explanation: Abiotic synthesis refers to the synthesis of organic molecules from inorganic compounds in the absence of oxygen.

10) (a) Hyperthermophiles can survive only at very high temperatures that are difficult to replicate in a lab setting

Explanations: Hyperthermophiles are organisms which inhabit extremes of high temperature environments and these conditions are difficult to study in a laboratory.

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