Question 1

Which of the following best describes the difference between homeothermy and poikilothermy?

Accepted Answer

Homeotherms maintain a constant body temperature, while poikilotherms have a variable body temperature that fluctuates with the environment.

Question 2

Which physiological adaptation allows homeotherms to produce more heat than poikilotherms?

Accepted Answer

Homeotherms have more extensive mitochondrial inner membranes that are leakier to $$\mathrm{H^+}$$ ions.

Question 3

Why is homeothermy considered energetically expensive?

Accepted Answer

Over 90% of energy consumed is converted directly into heat to maintain high body temperature.

Question 4

Which tissue is primarily responsible for non-shivering thermogenesis in mammals?

Accepted Answer

Brown adipose tissue (BAT)

Question 5

What is the role of uncoupling proteins in mitochondria during non-shivering thermogenesis?

Accepted Answer

They allow protons ($$\mathrm{H^+}) to $$leak across the inner mitochondrial membrane, generating heat instead of ATP.

Question 6

Which of the following strategies helps reduce the energetic cost of homeothermy in cold environments?

Accepted Answer

Increasing insulation to slow the rate of heat loss

Question 7

During hibernation, what happens to the metabolic rate and body temperature of a homeothermic mammal?

Accepted Answer

Metabolic rate drops by as much as 90%, followed by a decrease in body temperature.

Question 8

Which of the following best explains why small mammals like shrews have higher mass-specific metabolic rates than large mammals like elephants?

Accepted Answer

Small mammals lose heat more rapidly due to a higher surface area-to-volume ratio, requiring a higher metabolic rate to maintain body temperature.

Question 9

A hummingbird enters daily torpor at night. What is the primary benefit of this physiological state?

Accepted Answer

It saves energy by reducing metabolic rate and body temperature during periods of inactivity.

Question 10

Which of the following is true regarding the thermal neutral zone (TNZ) in homeotherms?

Accepted Answer

Within the TNZ, metabolic rate is at its lowest and does not change with ambient temperature.

Question 11

Which of the following statements about endothermy and ectothermy is correct?

Accepted Answer

Endotherms raise body temperature by producing heat metabolically, while ectotherms absorb heat from their environment.

Question 12

Which of the following is a real-world example of behavioral thermoregulation in ectotherms?

Accepted Answer

A Galapagos marine iguana basking in the sun to raise its body temperature.

Question 13

Which of the following equations best represents the relationship between metabolic rate ($$MR) $$and body mass ($$M) in $$mammals?

Accepted Answer

$$MR \propto M$$^{0.75}$$

Question 14

Which of the following physiological processes is NOT directly geared to an animal's metabolic rate?

Accepted Answer

Coloration of the skin

Question 15

During arousal from hibernation, which tissue is primarily used to rapidly increase body temperature?

Accepted Answer

Brown adipose tissue (BAT)

Question 16

Which of the following is a plausible explanation for the suppression of metabolic rate during hibernation?

Accepted Answer

Inhibition of the electron transport chain (ETC) in mitochondria

Question 17

Which of the following best explains why the basal metabolic rate (BMR) of a homeotherm is about 10 times higher than the standard metabolic rate (SMR) of a similarly sized poikilotherm?

Accepted Answer

Homeotherms require more energy to maintain a constant, high body temperature.

Question 18

Which of the following is NOT a benefit of homeothermy?

Accepted Answer

Lower energy expenditure compared to poikilotherms

Question 19

Which of the following animals is an example of an endothermic homeotherm?

Accepted Answer

A mammal such as a dog

Homeothermy, Endothermy, and Metabolic Adaptations in Animals

Study Guide - Practice Questions

Study Guide - Flashcards