It accumulates large amounts of K\textsuperscript{+} to remain slightly hypertonic to its environment.

Question 1

Which of the following adaptations allows acidophiles to maintain a neutral internal pH in highly acidic environments?

Accepted Answer

Their plasma membrane contains high levels of tetraether lipids that decrease permeability to H	extsuperscript{+}.

Question 2

A bacterium is found growing optimally at 4 M NaCl. Which of the following is most likely true about its cellular adaptations?

Accepted Answer

It accumulates large amounts of K	extsuperscript{+} to remain slightly hypertonic to its environment.

Question 3

Which of the following best explains why obligate anaerobes are unable to survive in the presence of oxygen?

Accepted Answer

They lack superoxide dismutase and catalase enzymes.

Question 4

Which type of lipid is characteristic of archaeal membranes and contributes to their ability to survive extreme environments?

Accepted Answer

Glycerol diether

Question 5

A microbe is isolated from a deep-sea hydrothermal vent at 110°C. Which of the following membrane adaptations is most likely present?

Accepted Answer

High proportion of cyclopentane rings in membrane lipids

Question 6

Which of the following best describes the heat shock response in bacteria?

Accepted Answer

Production of chaperone proteins that help prevent protein denaturation

Question 7

Which of the following scenarios best illustrates short-term adaptation in microbes?

Accepted Answer

Induction of heat shock proteins after a sudden temperature increase

Question 8

A facultative anaerobe is grown in a test tube with an oxygen gradient. Where would you expect to see the most growth?

Accepted Answer

Throughout the tube, but more at the top where oxygen is present

Question 9

Which of the following best explains why halophiles require high concentrations of K	extsuperscript{+} inside their cells?

Accepted Answer

To maintain osmotic balance and stabilize enzymes and proteins

Question 10

Which of the following is a likely adaptation of barophiles that allows them to survive at high pressures?

Accepted Answer

Enzymes and membranes adapted to resist pressure-induced denaturation

Question 11

Which of the following best describes the difference between evolutionary adaptation and short-term adaptation in microbes?

Accepted Answer

Evolutionary adaptation is permanent and occurs over generations, while short-term adaptation is temporary and reversible.

Question 12

Which of the following fatty acids would increase membrane fluidity at low temperatures?

Accepted Answer

Cis-unsaturated fatty acids

Question 13

A microbe is found growing in a hot spring with a pH of 2. Which of the following adaptations is most likely present?

Accepted Answer

High levels of tetraether lipids in the plasma membrane

Question 14

Which of the following best explains why enzymes in alkalophiles remain functional in basic environments?

Accepted Answer

Cell walls contain acidic polymers that neutralize bases outside the cell

Question 15

Which of the following is a consequence of exposing a mesophile to temperatures above its maximum growth range?

Accepted Answer

Protein denaturation and loss of membrane integrity

Question 16

Which of the following best describes the movement of water during osmosis in a cell placed in a hypertonic solution?

Accepted Answer

Water moves out of the cell, causing it to shrink

Question 17

Which of the following is a likely adaptation of psychrophiles that allows them to survive at low temperatures?

Accepted Answer

High proportion of unsaturated fatty acids in membranes

Question 18

Which of the following best explains why barosensitive organisms die as pressure increases?

Accepted Answer

Their membranes and proteins are damaged by high pressure

Question 19

Which of the following is a common feature of both acidophiles and alkalophiles that helps maintain intracellular homeostasis?

Accepted Answer

Plasma membranes with high levels of tetraether lipids

Microbial Adaptation to Environmental Factors

Study Guide - Practice Questions