Deck 25: Metabolism, Temperature Regulation and Environmental Stress

Question 1

Animals that change their resting metabolic rate in response to seasonal changes in their environment

A) undergo acclimation.
B) undergo acclimatisation.
C) show genotypic plasticity.
D) show seasonal metabolic compensation.
E) experience a genetically based change in phenotype.

Answer 1

undergo acclimatisation.

Question 2

Which of the following is an example of phenotypic plasticity?

A) In a population of peppered moths, the wings of some individuals are speckled, while those of others are uniformly dark.
B) Male reindeer grow a new set of antlers at the beginning of each breeding season. As a male grows older, he grows larger antlers with more branches.
C) Individuals of a particular species of intertidal barnacle have a short, squat body form in low-density populations and a tall, thin body form in high-density populations.
D) Whales migrate each year to breed in warmer water.
E) Over a number of generations the coat colour of a population of feral rabbits becomes noticeably darker.

Answer 2

Individuals of a particular species of intertidal barnacle have a short, squat body form in low-density populations and a tall, thin body form in high-density populations.

Question 3

The response of an organism to a change in one particular aspect of its environment is known as

A) genotypic plasticity.
B) acclimation.
C) acclimatisation.
D) compensation.
E) maturation.

Answer 3

acclimation.

Question 4

Why is phenotype plasticity best developed in plants?

A) There are a diverse number of extant plants.
B) Plants harden.
C) Plants have sedentary growth.
D) Plants have large genomes which enable them to respond to many environmental changes.
E) Plants have a high tolerance to extreme temperatures.

Question 5

Phenomena such as photoperiodism are called proximate factors. This means that they

A) trigger an organism to initiate an adaptive response.
B) are a response to an environmental signal.
C) are a response to seasonal stress.
D) are genetically predetermined.
E) initiate responses in nearby organisms.

Question 6

In an experiment, a fish that had been kept in a tank containing water at 25 $\degree$ C was transferred to water at 20 $\degree$ C. One hour after the transfer the metabolic rate of the fish was significantly reduced; however, after several days the metabolic rate of the fish had returned to its pre-transfer level. The metabolic changes experienced by the fish in this experiment demonstrate

A) genotypic plasticity.
B) natural selection.
C) acclimatisation.
D) acclimation.
E) compensation.

Question 7

Some termite species of the Australian arid zone keep the temperature in their nests relatively constant by

A) building the nest with an east-west orientation.
B) using insulating wood pulp as a building material.
C) blocking off air passages.
D) All of the answers are correct.
E) None of the answers are correct.

Question 8

By building their nest mounds with a north-south orientation, 'magnetic' termites living in northern Australia ensure that the

A) maximum area of the nest is exposed to the midday sun.
B) relative humidity inside the nest is always around 95 per cent.
C) air circulating through the internal air passages is always cooler than the ambient temperature.
D) maximise exposure to the direction of the rainfall and so maintain high humidity in the nest.
E) maximum area of the nest is exposed to the sun during periods of low temperatures.

Question 9

The most likely cause of damage to cells by freezing is

A) a change in the pH within the cells.
B) osmotic withdrawal of water from cells.
C) dehydration of intracellular proteins.
D) rupture of membranes by ice crystals.
E) a decrease in the concentrations of important intracellular ions.

Question 10

Insects living at low temperatures can increase body temperature by

A) living in sheltered microclimates.
B) developing thermal melanism.
C) basking.
D) reducing wing area.
E) All of the answers are correct.

Question 11

The rates of two biochemical reactions are measured and found to increase exponentially with temperature. At 5 $\degree$ C both reactions occur at the same rate; however, reaction A is less sensitive to temperature than reaction

A) Reaction A.
B) Reaction B.
C) Both reactions have the same Q10.
D) Q10 will change with the temperature of the reaction.
E) There is not enough information to tell.

Question 12

Animals that depend largely on external heat sources to maintain body temperatures above ambient are referred to as

A) endotherms.
B) ectotherms.
C) reptiles.
D) warm-blooded.
E) cold-blooded.

Question 13

In preparation for a physiological experiment an animal is placed in a temperature-controlled chamber and allowed to acclimate. During the experiment the temperature within the chamber is steadily increased and measurements of the animal's metabolic rate are taken at regular intervals. The results show that the metabolic rate of the animal decreases steadily over the first 15 $\degree$ C, remains constant for the next 5 $\degree$ C and then increases steeply over the final 10 $\degree$ C. You would predict that, during this experiment, the body temperature of the animal would

A) follow the same pattern as the metabolic rate.
B) increase steadily at the same rate as the temperature within the chamber.
C) increase steadily, but more slowly than the temperature within the chamber.
D) remain constant.
E) decrease as the temperature increases.

Question 14

Which of the following statements is true?

A) Endotherms have the ability to maintain a constant body temperature whereas ectotherms do not.
B) Endotherms have lower metabolic rates than ectotherms of the same body mass.
C) Both endotherms and ectotherms regulate their body temperature.
D) The body temperature of ectotherms is the same as the ambient temperature.
E) All of the answers are true.

Question 15

Stenothermal ectotherms

A) are thermoregulating animals.
B) have widely variable body temperatures.
C) need to expend considerable energy maintaining thermal homeostasis.
D) is biochemically advantageous to physiological processes.
E) are able to occupy diverse environments.

Question 16

In a species of mammal, the metabolic rate measured at 10 $\degree$ C in winter would be

A) higher than the metabolic rate measured at 10 $\degree$ C in summer.
B) lower than the metabolic rate measured at 10 $\degree$ C in summer.
C) lower than the metabolic rate measured at 25 $\degree$ C in winter.
D) higher than the metabolic rate measured at 25 $\degree$ C in winter.
E) the same as the metabolic rate measured at 10 $\degree$ C in summer.

Question 17

In a species of frog that undergoes seasonal metabolic compensation, the metabolic rate measured at 10 $\degree$ C in winter would be

A) higher than the metabolic rate measured at 10 $\degree$ C in summer.
B) lower than the metabolic rate measured at 10 $\degree$ C in summer.
C) the same as the metabolic rate measured at 25 $\degree$ C in winter.
D) higher than the metabolic rate measured at 25 $\degree$ C in winter.
E) the same as the metabolic rate measured at 10 $\degree$ C in summer.

Question 18

Which of the following statements about torpor is true?

A) Torpor is a type of natural hypothermia occurring only in endotherms.
B) When a mammal enters torpor the body temperature drops in response to a drop in metabolic rate.
C) Torpor enables small animals to conserve energy stores during periods of non-feeding.
D) Entry into torpor is indicated by a steep increase in oxygen consumption.
E) The lower body temperature in torpor is associated with increased heart rate.

Question 19

Cryoprotectants are organic molecules such as _______, which protect _______ against cold-induced damage. Fill in the blanks in this statement.

A) proteins, enzymes.
B) carbohydrates, secretions.
C) sugars, membranes.
D) fats, intracellular fluids.
E) sugars, enzymes.

Question 20

When a mammal such as a pygmy possum arouses from torpor, which of the following physiological changes is most effective in initially increasing temperature?

A) An increase in body temperature.
B) An increase in cardiac output and blood flow to the brain.
C) Increased digestive activity.
D) The metabolism of brown fat reserves.
E) Shivering.

Question 21

Relative to the open sea, tidal pools have

A) a lower partial pressure of oxygen.
B) a higher partial pressure of oxygen.
C) the same partial pressure of oxygen.
D) oxygen content dependent on the surrounding sea.
E) Any of these, depending on time of day, tidal conditions and amount of photosynthesis occurring.

Question 22

North American prairie dogs build a mound at one of the two entrances to their burrows. The entrance on the mound (A) is higher than the other entrance (B), and is therefore exposed to greater wind speeds. This

A) causes a negative pressure at the higher entrance, sucking a current of air through the burrow, from B to A.
B) causes a positive pressure at the higher entrance, forcing a current of air through the burrow, from A to B.
C) results in a ventilating current of air from A to B when the animal shuffles in and out of entrance B.
D) causes air to move through the burrow in either direction, depending on the magnitude of the difference in wind speed between the two entrances.
E) enables the animal to move to the entrance with higher oxygen intake.

Question 23

Which of the following physiological changes occurs during the diving response in vertebrates?

A) Increased heart rate
B) Decreased arterial pressure
C) Increased tolerance to high concentrations of lactic acid in the blood
D) Decreased blood flow to muscles involved in locomotion
E) Decreased heart rate

Question 24

All of the following physiological changes are characteristic of the vertebrate diving response and also of torpor, EXCEPT

A) bradycardia.
B) peripheral vasoconstriction.
C) decreased rate of oxygen consumption.
D) reduced blood circulation.
E) a build up of lactic acid in the blood.

Question 25

As altitude increases, which of the following atmospheric changes occurs for every 5500 m gained?

A) The proportion of oxygen decreases by 50 per cent.
B) The proportion of oxygen increases by 50 per cent.
C) The partial pressure of oxygen decreases by 50 per cent.
D) The partial pressure of oxygen increases by 50 per cent.
E) There is little change in oxygen pressure until altitudes greater than 10,000 m.

Question 26

People acclimatised to life at high altitudes show

A) a decrease in the number of red blood cells.
B) an increase in the number of capillaries.
C) a decrease in the concentration of haemoglobin.
D) an increase in heart rate.
E) decrease in myoglobin concentration in muscles.

Question 27

It is advantageous for athletes to train at high altitudes for several weeks before an important competition at sea level, because during this time they develop an increase in

A) the affinity of their haemoglobin for oxygen.
B) the concentration of haemoglobin in their blood.
C) their heart rate.
D) their lung capacity.
E) the partial pressure of O₂ at which their haemoglobin is saturated.

Question 28

When compared with its rate of diffusion in air, the rate of diffusion of a gas in water

A) is faster.
B) is the same.
C) is slower.
D) is dependent on the temperature of the water.
E) fluctuates.

Question 29

Which of the following statements regarding birds and mammals at high altitudes is false?

A) The embryos have lower haemoglobin concentrations than embryos at sea level.
B) Bird eggs are smaller than eggs at sea level.
C) The overall diffusive conductance of bird eggs is similar to eggs at sea level.
D) The hatching of bird eggs is restricted.
E) Their muscles contain a higher concentration of myoglobin than the animals at sea level.

Question 30

When exposed to acutely hypoxic conditions, many endotherms lower their body temperature. This response is advantageous because

A) there is an associated drop in metabolic rate.
B) it causes a decrease in the affinity of haemoglobin for O₂.
C) it triggers hyperventilation and increased cardiac output.
D) less oxygen is taken from the blood by the myoglobin in muscles.
E) All of the answers are correct.

Question 31

Body temperature

A) is directly proportional to the animal's metabolic rate.
B) is related to the animal's activity.
C) is controlled over a very narrow temperature range.
D) is dependent on ambient temperature.
E) may range from -2 $\degree$ C to 80 $\degree$ C in different animals.

Question 32

Factors affecting metabolic rate include all of the following, EXCEPT

A) level of activity.
B) sunshine.
C) body temperature.
D) stage of development.
E) state of digestion.

Question 33

Endotherms

A) use thermal metabolic heat to enable them to occupy environments that are too variable for ectotherms.
B) rely on external sources of heat to determine their body temperature.
C) have a species-specific temperature set point around which they preferentially regulate body temperature.
D) are highly active animals.
E) are typically reptiles and fish.

Question 34

Eurytherms

A) are thermoregulating animals.
B) have widely variable body temperatures.
C) need to expend considerable energy maintaining thermal homeostasis.
D) is biochemically advantageous to physiological processes.
E) are able to occupy diverse environments.

Question 35

Which of the following statements is CORRECT?

A) Thigmotherms use conductive heat gain as their major mechanism to increase body temperature above ambient temperature.
B) Many ectotherms are thigmotherms, gaining most of their heat from solar radiation.
C) Aquatic ectotherms have more scope to manipulate temperature than terrestrial ectotherms.
D) Heliotherms maintain precisely regulated body temperature well below ambient temperatures.
E) Ectothermes tend to cool more rapidly than they heat, and frequently overshoot high temperature set-points.

Question 36

Which of the following statements is CORRECT?

A) Many animals form burrows with good ventilation to prevent hypoxia.
B) At high altitudes, increase in breathing results in increased partial pressure of CO₂ in the lung.
C) In the diving response, mammals store oxygen and increase heart rate to prevent hypoxia.
D) Both ectoderms and endotherms may lower their body temperature in response to hypoxia.
E) Birds at high altitude have decreased haemoglobin to prevent hypoxia.

Question 37

Most reptiles are ectotherms. A snake that keeps its eggs warm by coiling around them and shivering to maintain a constant, higher body temperature would be an

A) Ectotherm
B) Ecotherm
C) Homeotherm
D) Endotherm
E) Polytherm

Question 38

Gigantotherms

A) are restricted to relatively warm environments.
B) are very large terrestrial ectotherms.
C) have a small surface area to volume ratio.
D) have a thick integument.
E) all of the options listed here are correct.

Question 39

A small child is given a gift labelled 'sea monkeys'. At first glance it appears to consist of nothing but dehydrated and lifeless granules. However, when placed in water, the granules turn out to be small brine shrimp that display vigorous signs of life. This is an example of

A) genetic modification.
B) resurrection.
C) cryptobiosis.
D) endothermosis.
E) ectothermosis.

Question 40

How do African and South American lungfish cope with the extreme environmental stress associated with the complete desiccation of the ponds they typically live in?

A) They burrow down into the mud, produce a cocoon of mucus and remain inactive until environmental conditions become favourable.
B) They die.
C) They have swim bladders that can adapt to act as a crude lung, allowing them to travel overland to the nearest body of fresh water.
D) They dry out completely and remain on the pond floor as a dry husk, but regain activity when moisture returns.
E) They excrete a small, toughened spore with an extremely tough and desiccation resistant outer layer that lies dormant until water returns to the pond, thus regenerating a juvenile lungfish from the spore.

Question 41

An animal presents at a veterinary hospital with suspected pathological hypothermia. In response to this preliminary diagnosis you should

A) do nothing, the animal is in a state of torpor and will rouse once seasonal conditions are favourable.
B) attempt to increase the animal's core temperature to normothermic values.
C) attempt to decrease the animal's core temperature to normothermic values.
D) wait, the animal is in a nocturnal hypothermic state and its body temperature will return to normal in a relatively short period of time.
E) ensure the animal's affairs are in order - it's a goner.

Question 42

A decrease in the partial pressure of O₂ from normal O₂ levels can result in

A) all the options listed here are correct.
B) restricted diffusion of O₂ across membranes.
C) reduction of O₂ availability to tissues.
D) sorroche.
E) alkalosis.

Question 43

While climbing a very high mountain, a climber complains of dizziness, headache, nausea, palpitations and insomnia. The climber is probably suffering from

A) hypothermia.
B) hypoxia.
C) hyperthermia.
D) hyperanoxia.
E) hyperoxic anaemia.

Question 44

Which of the following is NOT a response to an extended low partial pressure of oxygen?

A) Lowered torpor response threshold
B) More efficient O₂ binding red blood cells.
C) Lowering of body temperature
D) Depression of thermogenesis
E) Drop in metabolic rate

Question 45

A small mammal is found to have a reduced response to breathing stimuli such as low oxygen, partial pressure and high CO₂ levels. In addition, it also has a relatively low body temperature and metabolic rate. As such, this animal almost certainly spends a significant amount of its time in what kind of environment?

A) Aarid or semi-arid
B) Thick undergrowth
C) Underground burrow
D) Fresh water
E) Grasslands