Lecture 19: Thermal Physiology Part 2

Question 1

What is a quantitative strategy in the long-term response of ectotherms to temperature?
a) Altering the type of metabolic machinery
b) Changing the amount of metabolic machinery
c) Relying on behavioral thermoregulation
d) Increasing protein instability

Answer 1

Answer: b) Changing the amount of metabolic machinery

Question 2

Which of the following is an example of a quantitative strategy?
a) Producing different isoforms of muscle proteins for winter and summer
b) Increasing the number of muscle mitochondria at low temperatures
c) Changing the fatty acid composition of cell membranes
d) Decreasing energy expenditure during cold temperatures

Answer 2

Answer: b) Increasing the number of muscle mitochondria at low temperatures

Question 3

What is a qualitative strategy in the long-term response of ectotherms to temperature?
a) Altering the amount of metabolic machinery
b) Increasing energy reserves during cold periods
c) Altering the type of metabolic machinery
d) Decreasing enzymatic activity at high temperatures

Answer 3

Answer: c) Altering the type of metabolic machinery

Question 4

What does a qualitative strategy allow ectotherms to do?
a) Enhance performance in warm temperatures
b) Enhance performance in cold temperatures
c) Maintain a constant body temperature
d) Reduce metabolic activity

Answer 4

Answer: b) Enhance performance in cold temperatures

Question 5

Which of the following is an example of a qualitative strategy?
a) Increasing the number of muscle mitochondria
b) Producing heat-resistant proteins in summer
c) Producing different isoforms of muscle proteins for winter and summer
d) Reducing metabolic rate to save energy

Answer 5

Answer: c) Producing different isoforms of muscle proteins for winter and summer

Question 6

Why might proteins produced as part of a qualitative strategy become unstable?
a) Due to high energy demands
b) When exposed to higher temperatures
c) If the number of mitochondria is increased
d) When external temperatures remain constant

Answer 6

Answer: b) When exposed to higher temperatures

Question 7

Why do ectotherms remodel their tissues in response to temperature changes?
a) To avoid using behavioral strategies
b) To adapt their metabolic processes to different thermal conditions
c) To minimize energy use at all temperatures
d) To maintain a constant body temperature like endotherms

Answer 7

Answer: b) To adapt their metabolic processes to different thermal conditions

Question 8

What is the difference between qualitative and quantitative strategies used by ectotherms in long-term (chronic) responses to temperature changes?

a) Qualitative strategies involve altering the type of metabolic machinery, such as producing different isoforms of proteins for cold and warm conditions, while quantitative strategies involve changing the amount of metabolic machinery, such as increasing the number of muscle mitochondria.
b) Qualitative strategies involve increasing the number of mitochondria, while quantitative strategies involve changing fatty acid composition.
c) Qualitative strategies are short-term and behavioral, while quantitative strategies are long-term and physiological.
d) Qualitative strategies are passive, while quantitative strategies are active.

Answer 8

a)

Question 9

What does the process of acclimation allow ectotherms to do?
a) Fully return their metabolic rate to what it would be at warmer temperatures.
b) Completely compensate for temperature changes.
c) Partially compensate by increasing their metabolic rate in colder conditions.
d) Prevent any changes in body temperature or metabolic rate.

Answer 9

Answer: c) Partially compensate by increasing their metabolic rate in colder conditions.

Question 10

In the thermal performance curve for ectotherms, what does the “Pejus range” represent?
a) The range where performance is at its peak.
b) The range where performance begins to decline due to suboptimal temperatures.
c) The range where proteins become denatured.
d) The range where death occurs due to extreme temperatures.

Answer 10

Answer: b) The range where performance begins to decline due to suboptimal temperatures.

Question 11

What happens to the mitochondrial abundance in the muscles of cold-acclimated fish compared to warm-acclimated fish?
a) It decreases.
b) It remains unchanged.
c) It increases.
d) It fluctuates randomly.

Answer 11

Answer: c) It increases.

Question 12

What term describes the inability of acclimation to fully restore the metabolic rate to its previous level before the temperature change?
a) Full compensation
b) Partial compensation
c) Thermal inertia
d) Metabolic overcompensation

Answer 12

Answer: b) Partial compensation

Question 13

What does membrane fluidity measure?
a) The strength of the membrane against environmental stress
b) How readily phospholipid molecules move within the membrane
c) The thickness of the lipid bilayer
d) The number of proteins embedded in the membrane

Answer 13

Answer: b) How readily phospholipid molecules move within the membrane

Question 14

How does temperature affect membrane fluidity?
a) Low temperatures cause membrane lipids to liquefy, while high temperatures cause them to solidify.
b) Low temperatures cause membrane lipids to solidify, while high temperatures cause them to liquefy.
c) Membrane fluidity remains constant regardless of temperature.
d) Membrane proteins determine fluidity, not temperature.

Answer 14

Answer: b) Low temperatures cause membrane lipids to solidify, while high temperatures cause them to liquefy.

Question 15

Why is maintaining proper membrane fluidity important?
a) It prevents the membrane from rupturing under stress.
b) It allows proteins within the membrane to move and function properly.
c) It ensures the membrane maintains a constant thickness.
d) It prevents lipids from interacting with environmental factors.

Answer 15

Answer: b) It allows proteins within the membrane to move and function properly.

Question 16

What happens to protein movement when membrane fluidity increases?
a) Protein movement increases.
b) Protein movement decreases.
c) Protein movement is unaffected.
d) Proteins break down due to high fluidity.

Answer 16

Answer: a) Protein movement increases.

Question 17

How do animals adapt their membranes to maintain fluidity at low temperatures?
a) They increase the proportion of unsaturated fatty acids in the membrane.
b) They increase the proportion of saturated fatty acids in the membrane.
c) They increase the number of membrane proteins.
d) They decrease phospholipid movement.

Answer 17

Answer: a) They increase the proportion of unsaturated fatty acids in the membrane.

Question 18

Which of the following is a qualitative strategy for maintaining membrane function at extreme temperatures?
a) Adjusting the amount of mitochondria in cells.
b) Altering the type of metabolic machinery, such as membrane lipids.
c) Increasing metabolic rate to compensate for changes in temperature.
d) Reducing enzyme activity to conserve energy.

Answer 18

Answer: b) Altering the type of metabolic machinery, such as membrane lipids.

Question 19

What is the purpose of homeoviscous adaptation?
a) To maintain constant protein function regardless of temperature
b) To maintain consistent membrane fluidity across different temperatures
c) To increase membrane rigidity in all conditions
d) To prevent fatty acid saturation in warm temperatures

Answer 19

Answer: b) To maintain consistent membrane fluidity across different temperatures

Question 20

How do unsaturated fatty acids affect membrane fluidity?
a) They make the membrane more rigid and less fluid.
b) They decrease the number of double bonds in the membrane.
c) They create kinks in fatty acid tails, increasing fluidity.
d) They cause phospholipids to stack tightly together.

Answer 20

Answer: c) They create kinks in fatty acid tails, increasing fluidity.

Question 21

Why do cold-acclimated animals increase the proportion of unsaturated fatty acids in their membranes?
a) To increase the rigidity of the membrane
b) To prevent membranes from becoming too fluid
c) To enhance membrane fluidity and prevent solidification
d) To remove all fatty acids from the membrane

Answer 21

Answer: c) To enhance membrane fluidity and prevent solidification

Question 22

What is the primary difference between saturated and unsaturated fatty acids in membrane phospholipids?
a) Saturated fatty acids contain double bonds, while unsaturated fatty acids do not.
b) Saturated fatty acids stack tightly, while unsaturated fatty acids create more space due to kinks in their structure.
c) Saturated fatty acids are liquid at room temperature, while unsaturated fatty acids are solid.
d) Saturated fatty acids increase membrane fluidity, while unsaturated fatty acids decrease it.

Answer 22

Answer: b) Saturated fatty acids stack tightly, while unsaturated fatty acids create more space due to kinks in their structure.

Question 23

How does homeoviscous adaptation help species maintain proper membrane function?
a) By ensuring consistent membrane fluidity regardless of environmental temperature
b) By decreasing the proportion of phospholipids in the membrane
c) By eliminating all saturated fatty acids from the membrane
d) By producing fewer unsaturated fatty acids over time

Answer 23

Answer: a) By ensuring consistent membrane fluidity regardless of environmental temperature

Question 24

What trend is observed in Antarctic fish compared to tropical fish in terms of fatty acid composition?
a) Antarctic fish have fewer double bonds in their fatty acids.
b) Antarctic fish have more double bonds in their fatty acids.
c) Tropical fish have more double bonds in their fatty acids.
d) Both Antarctic and tropical fish have the same fatty acid composition.

Answer 24

Answer: b) Antarctic fish have more double bonds in their fatty acids.

Question 25

Why do cold-adapted species have more unsaturated fatty acids in their membranes?
a) To reduce energy expenditure at low temperatures
b) To increase fluidity and prevent the membrane from solidifying
c) To increase membrane rigidity for stability
d) To improve the efficiency of saturated fatty acids

Answer 25

Answer: b) To increase fluidity and prevent the membrane from solidifying

Question 26

What are the two main strategies ectotherms use to survive sub-zero temperatures?
a) Freeze-avoidance and heat production
b) Freeze-intolerance and freeze-tolerance
c) Heat conservation and freeze-production
d) Supercooling and hibernation

Answer 26

Answer: b) Freeze-intolerance and freeze-tolerance

Question 27

Which of the following is a strategy used by freeze-intolerant animals to avoid freezing?
a) Producing antifreeze compounds
b) Allowing ice to form in extracellular spaces
c) Reducing metabolic activity to conserve energy
d) Removing water from their cells

Answer 27

Answer: a) Producing antifreeze compounds

Question 28

What distinguishes freeze-tolerant animals from freeze-intolerant animals?
a) Freeze-tolerant animals produce antifreeze compounds.
b) Freeze-tolerant animals allow their tissues to freeze.
c) Freeze-intolerant animals can tolerate desiccation.
d) Freeze-intolerant animals rely on osmosis to survive freezing.

Answer 28

Answer: b) Freeze-tolerant animals allow their tissues to freeze.

Question 29

Why is freezing problematic for animal cells?
a) It reduces the fluidity of cell membranes.
b) Ice crystals can puncture cell membranes.
c) Freezing causes a solute imbalance; more solute inside than outside the cell
d) It increases protein stability.
e) b & c

Answer 29

Answer: b and c

Question 30

What happens when ice crystals form outside the cell?
a) Solutes inside the cell move outward to maintain equilibrium.
b) Water moves out of the cell due to osmosis, leading to desiccation.
c) Ice crystals dissolve rapidly in extracellular fluids.
d) The ionic balance of the cell is unaffected.

Answer 30

Answer: b) Water moves out of the cell due to osmosis, leading to desiccation.

Question 31

Which ectotherm is an example of a freeze-tolerant species?
a) Wood frog
b) Green anole
c) Bass
d) Trout

Answer 31

Answer: a) Wood frog

Question 32

How do antifreeze compounds help freeze-intolerant animals?
a) They prevent ice formation by lowering the freezing point of body fluids.
b) They encourage the formation of extracellular ice to protect the cell.
c) They increase the production of water inside the cell.
d) They solidify the extracellular space to stabilize ionic balance.

Answer 32

Answer: a) They prevent ice formation by lowering the freezing point of body fluids.

Question 33

What are the two primary mechanisms freeze-intolerant animals use to survive sub-zero temperatures?

a) Hibernation and migration
b) Supercooling and antifreeze compounds
c) Ice formation and osmosis
d) Metabolic rate reduction and desiccation

Answer 33

b)

Question 34

What are the two primary mechanisms freeze-intolerant animals use to avoid freezing, and how do they function?

a) Antifreeze compounds (colligative and noncolligative) and behavioral avoidance
b) Antifreeze compounds (colligative and noncolligative) and supercooling
c) Supercooling and freezing of extracellular fluids
d) Osmosis and metabolic rate reduction

Answer 34

b)

Question 35

How do colligative antifreeze compounds work in freeze-intolerant animals?
a) They bind to ice crystals to prevent further growth.
b) They increase solute concentration to lower the freezing point.
c) They remove water from the cell to prevent freezing.
d) They prevent the formation of gas bubbles in tissues.

Answer 35

Answer: b) They increase solute concentration to lower the freezing point.

Question 36

Which of the following is an example of a colligative antifreeze compound?
a) Antifreeze glycoproteins
b) Glycerol
c) Mannose
d) Hemoglobin

Answer 36

Answer: b) Glycerol

Question 37

Which of the following describes supercooling?
a) The process of preventing freezing by increasing metabolic activity
b) The ability to maintain liquid water below 0°C in the absence of nucleators
c) The active removal of water from tissues to prevent ice formation
d) The freezing of extracellular fluids while protecting cells

Answer 37

Answer: b) The ability to maintain liquid water below 0°C in the absence of nucleators

Question 38

What is the primary role of noncolligative antifreeze compounds?
a) Increase solute concentration to lower the freezing point
b) Bind to ice crystals and disrupt their growth
c) Remove nucleating agents from tissues
d) Reduce the metabolic rate during freezing

Answer 38

Answer: b) Bind to ice crystals and disrupt their growth

Question 39

What are ice-nucleating agents, and how do they affect supercooling?
a) They decrease the freezing point of water and promote supercooling.
b) They act as triggers for ice formation, preventing supercooling.
c) They stabilize water in the liquid state below 0°C.
d) They increase membrane fluidity in cold environments.

Answer 39

Answer: b) They act as triggers for ice formation, preventing supercooling.

Question 40

What is the key difference between colligative and noncolligative antifreeze compounds?
a) Colligative antifreezes bind to ice crystals, while noncolligative antifreezes increase solute concentration.
b) Colligative antifreezes increase solute concentration, while noncolligative antifreezes disrupt ice crystal formation.
c) Colligative antifreezes act in warm environments, while noncolligative antifreezes act in cold environments.
d) Colligative antifreezes prevent nucleator formation, while noncolligative antifreezes stabilize membranes.

Answer 40

Answer: b) Colligative antifreezes increase solute concentration, while noncolligative antifreezes disrupt ice crystal formation.

Question 41

What is a key characteristic of freeze-tolerant species?
a) They prevent ice formation at all costs.
b) They allow ice to form only in specific extracellular locations.
c) They rely entirely on behavioral thermoregulation.
d) They produce antifreeze compounds to avoid freezing.

Answer 41

Answer: b) They allow ice to form only in specific extracellular locations.

Question 42

What is the primary difference between freeze-intolerant and freeze-tolerant animals?
a) Freeze-intolerant animals can survive freezing, while freeze-tolerant animals cannot.
b) Freeze-intolerant animals must prevent freezing entirely, while freeze-tolerant animals allow controlled freezing in specific locations.
c) Freeze-intolerant animals rely on solute production, while freeze-tolerant animals use behavioral thermoregulation.
d) Freeze-intolerant animals freeze intracellularly, while freeze-tolerant animals freeze extracellularly.

Answer 42

Answer: b) Freeze-intolerant animals must prevent freezing entirely, while freeze-tolerant animals allow controlled freezing in specific locations.

Question 43

Which of the following is true of freeze-intolerant animals but not freeze-tolerant animals?
a) They use supercooling to avoid ice formation.
b) They produce solutes to reduce osmotic gradients.
c) They direct ice crystal formation to extracellular spaces.
d) They rely on ice-nucleating agents to manage freezing.

Answer 43

Answer: a) They use supercooling to avoid ice formation.

Question 44

Which of the following is true of freeze-tolerant animals but not freeze-intolerant animals?
a) They produce antifreeze glycoproteins to prevent ice formation.
b) They control the location of ice crystal growth.
c) They rely on colligative antifreeze compounds to lower the freezing point of their body fluids.
d) They must avoid freezing at all costs.

Answer 44

Answer: b) They control the location of ice crystal growth.

Question 45

What strategies are employed by freeze-tolerant animals to survive freezing?

Answer 45

Produce nucleators outside the cell:

Direct ice crystal formation to extracellular spaces.
Extracellular freezing prevents damage to the intracellular environment.
Nucleators include calcium salts and membrane phospholipids.
Counter the movement of water:

Produce solutes (e.g., from liver glycogen breakdown) to increase intracellular osmolarity.
Intracellular solutes reduce osmotic gradients, preventing cell shrinkage.
Extracellular solutes limit excessive ice formation.