Question 1

What is the only mammal bereft of a pleural space, and what is the reason for this unusual modification?

Accepted Answer

A)  Kangaroos, to minimise lung bruising from hopping activity. 
B)  Pygmy possum, to allow very small lungs the ability to expand sufficiently. 
C)  Bats, to facilitate flying and minimise sonar disruption. 
D)  Emus, a vestigial remnant from adaption to a terrestrial existence. 
E)  Elephants, allowing them to breathe through their trunks at depth. 
A)  Kangaroos, to minimise lung bruising from hopping activity. 
B)  Pygmy possum, to allow very small lungs the ability to expand sufficiently. 
C)  Bats, to facilitate flying and minimise sonar disruption. 
D)  Emus, a vestigial remnant from adaption to a terrestrial existence. 
E)  Elephants, allowing them to breathe through their trunks at depth. E

Question 2

Different respiratory pigments have different affinities for O2. The difference in O2 affinity of human fetal and maternal haemoglobin enables the transfer of O2 from the mother's blood to fetal blood in the placenta. For this to be possible

Accepted Answer

A)  fetal haemoglobin has a lower affinity for O2 than maternal haemoglobin. 
B)  fetal haemoglobin and maternal haemoglobin have the same affinity for O2. 
C)  fetal O2 uptake takes place at lower partial pressures of O2 than maternal O2 uptake. 
D)  fetal haemoglobin binds oxygen irreversibly. 
E)  fetal O2 uptake takes place at higher partial pressures of O2 than maternal O2 uptake. 
A)  fetal haemoglobin has a lower affinity for O2 than maternal haemoglobin. 
B)  fetal haemoglobin and maternal haemoglobin have the same affinity for O2. 
C)  fetal O2 uptake takes place at lower partial pressures of O2 than maternal O2 uptake. 
D)  fetal haemoglobin binds oxygen irreversibly. 
E)  fetal O2 uptake takes place at higher partial pressures of O2 than maternal O2 uptake. C

Question 3

Protons are unable to pass through the blood-brain barrier, but CO2 can. As such, the chemoreceptors located in the medulla regulate the pH of cerebral interstitial fluid as a reflection of changes in the partial pressure of

Accepted Answer

A)  pH. 
B)  CO2. 
C)  proton gradients. 
D)  electrochemical gradients. 
E)  O2. 
A)  pH. 
B)  CO2. 
C)  proton gradients. 
D)  electrochemical gradients. 
E)  O2. B

Question 4

Along what kind of gradient do gasses diffuse across membranes?

Accepted Answer

A)  Plank's constant gradient 
B)  Molarity gradient 
C)  Osmotic gradient 
D)  Partial pressure gradient 
E)  Concentration gradient 
A)  Plank's constant gradient 
B)  Molarity gradient 
C)  Osmotic gradient 
D)  Partial pressure gradient 
E)  Concentration gradient

Question 5

For crustaceans with gills housed in branchial chambers, ventilation is maintained by

Accepted Answer

A)  cilia. 
B)  scaphognathites. 
C)  swimming appendages. 
D)  natural currents. 
E)  flagella. 
A)  cilia. 
B)  scaphognathites. 
C)  swimming appendages. 
D)  natural currents. 
E)  flagella.

Question 6

Gas exchange is

Accepted Answer

A)  the production of ATP at mitochondria. 
B)  cellular respiration. 
C)  the movement of O2 and CO2 between the environment and mitochondria. 
D)  the diffusion of O2 through cells in large organisms. 
E)  the removal of CO2 from cells by diffusion. 
A)  the production of ATP at mitochondria. 
B)  cellular respiration. 
C)  the movement of O2 and CO2 between the environment and mitochondria. 
D)  the diffusion of O2 through cells in large organisms. 
E)  the removal of CO2 from cells by diffusion.

Question 7

Cutaneous gas exchange is

Accepted Answer

A)  characteristic of annelids. 
B)  the primary form of gas exchange for many fish. 
C)  common in reptiles. 
D)  typical of larger animals because they lack protective outer surfaces. 
E)  limited to larger organisms with protective outer surfaces. 
A)  characteristic of annelids. 
B)  the primary form of gas exchange for many fish. 
C)  common in reptiles. 
D)  typical of larger animals because they lack protective outer surfaces. 
E)  limited to larger organisms with protective outer surfaces.

Question 8

An animal that had gill arches with many gill filaments was caught. Each gill filament had many vertically stacked lamellae. The gills were found to be heavily vascularised. Before being caught, the animal was tracked for several hours and observed to swim continuously. No evidence was found of a double-action pump or specialised appendages for ventilation. The animal is most likely to be a

Accepted Answer

A)  subtidal crab. 
B)  terrestrial crab. 
C)  tuna. 
D)  stingray. 
E)  shark. 
A)  subtidal crab. 
B)  terrestrial crab. 
C)  tuna. 
D)  stingray. 
E)  shark.

Question 9

Respiratory pigments include a metallic ion. What is the ion present in haemocyanin, and what is the role of these ions in respiratory pigments?

Accepted Answer

A)  Iron, which increases the O2 carrying capacity of the pigment 
B)  Magnesium, which increases the O2 diffusion gradient in pigments 
C)  Molybdenum, which prevents O2 being outcompeted by CO2 and CO in binding to the ion transport pigment 
D)  Cadmium, which binds to and strengthens the structural integrity of the pigment, preventing its otherwise rapid degradation due to its inherent instability in a high O2 environment 
E)  Copper, which increases the O2 carrying capacity of the pigment 
A)  Iron, which increases the O2 carrying capacity of the pigment 
B)  Magnesium, which increases the O2 diffusion gradient in pigments 
C)  Molybdenum, which prevents O2 being outcompeted by CO2 and CO in binding to the ion transport pigment 
D)  Cadmium, which binds to and strengthens the structural integrity of the pigment, preventing its otherwise rapid degradation due to its inherent instability in a high O2 environment 
E)  Copper, which increases the O2 carrying capacity of the pigment

Question 10

The presence of surfactant in mammalian lungs

Accepted Answer

A)  prevents alveolar collapse. 
B)  means that all alveoli must be the same size. 
C)  increases surface tension inside each alveolus. 
D)  is due to secretions from the tracheae. 
E)  is synthesised in the bronchiole cells. 
A)  prevents alveolar collapse. 
B)  means that all alveoli must be the same size. 
C)  increases surface tension inside each alveolus. 
D)  is due to secretions from the tracheae. 
E)  is synthesised in the bronchiole cells.

Question 11

The following is a list of features associated with respiratory systems.
1) Countercurrent exchange
2 )Cross-current exchange
3 )Tidal ventilation
4 )Unidirectional flow of respiratory medium across the respiratory surface
5 )Compliant air sacs in association with a stiff multitubular gas exchange surface
6 )Compliant lungs with many small chambers
Which collection of features would provide the most efficient gas exchange mechanism for an air breather?

Accepted Answer

A)  2, 3, 6. 
B)  1, 4, 6. 
C)  2, 3, 5. 
D)  1, 4, 5. 
E)  1, 3, 5. 
A)  2, 3, 6. 
B)  1, 4, 6. 
C)  2, 3, 5. 
D)  1, 4, 5. 
E)  1, 3, 5.

Question 12

Animals were able to increase in size and become multicellular because of the

Accepted Answer

A)  high diffusion rates of oxygen in aqueous media. 
B)  development of cellular respiration. 
C)  development of lungs. 
D)  development of mechanisms for efficient gas exchange and internal transport. 
E)  maintenance of a good convective flow of fluid past the gas-exchange surface. 
A)  high diffusion rates of oxygen in aqueous media. 
B)  development of cellular respiration. 
C)  development of lungs. 
D)  development of mechanisms for efficient gas exchange and internal transport. 
E)  maintenance of a good convective flow of fluid past the gas-exchange surface.

Question 13

Which of the following statements is true?

Accepted Answer

A)  The amount of gas in solution is determined solely by the partial pressure of the gas and the temperature. 
B)  The solubility of a gas is independent of the salinity of the solution. 
C)  An increase in temperature decreases the capacitance of CO2 and O2 in water. 
D)  The capacitance of water for CO2 is much lower than for O2. 
E)  Carbon dioxide is insoluble in water. 
A)  The amount of gas in solution is determined solely by the partial pressure of the gas and the temperature. 
B)  The solubility of a gas is independent of the salinity of the solution. 
C)  An increase in temperature decreases the capacitance of CO2 and O2 in water. 
D)  The capacitance of water for CO2 is much lower than for O2. 
E)  Carbon dioxide is insoluble in water.

Question 14

The metabolic products produced by the tissue of an energetically active mammal enter the bloodstream. What are two of these products and how do they affect the O2 affinity of haemoglobin?

Accepted Answer

A)  CO2 and heat, which raise the O2 affinity of haemoglobin. 
B)  O2 and peruvic acid, which lower the O2 affinity of haemoglobin. 
C)  CO and lactic acid, which raise the O2 affinity of haemoglobin. 
D)  CO2 and heat, which lower the O2 affinity of haemoglobin. 
E)  H2O and heat, which raise the O2 affinity of haemoglobin. 
A)  CO2 and heat, which raise the O2 affinity of haemoglobin. 
B)  O2 and peruvic acid, which lower the O2 affinity of haemoglobin. 
C)  CO and lactic acid, which raise the O2 affinity of haemoglobin. 
D)  CO2 and heat, which lower the O2 affinity of haemoglobin. 
E)  H2O and heat, which raise the O2 affinity of haemoglobin.

Question 15

In terms of gas exchange, the evolution of large animals was dependent on

Accepted Answer

A)  development of a gas-exchange system. 
B)  the ability to ventilate and so renew the external medium. 
C)  development of an internal circulatory system. 
D)  the ability of the gas to diffuse across the boundary layer of cells. 
E)  All of the answers are correct. 
A)  development of a gas-exchange system. 
B)  the ability to ventilate and so renew the external medium. 
C)  development of an internal circulatory system. 
D)  the ability of the gas to diffuse across the boundary layer of cells. 
E)  All of the answers are correct.

Question 16

A prerequisite for a terrestrial existence was the development of

Accepted Answer

A)  a four-chambered heart. 
B)  an internally housed gas-exchange system. 
C)  lungs. 
D)  chitinous covering to strengthen gills. 
E)  countercurrent circulation. 
A)  a four-chambered heart. 
B)  an internally housed gas-exchange system. 
C)  lungs. 
D)  chitinous covering to strengthen gills. 
E)  countercurrent circulation.

Question 17

Respiratory pigments in animals

Accepted Answer

A)  are needed because the concentration of oxygen is low in physiological fluid. 
B)  are always packaged into erythrocytes. 
C)  bind irreversibly with oxygen. 
D)  work independently of the partial pressure of oxygen. 
E)  are only found in vertebrates. 
A)  are needed because the concentration of oxygen is low in physiological fluid. 
B)  are always packaged into erythrocytes. 
C)  bind irreversibly with oxygen. 
D)  work independently of the partial pressure of oxygen. 
E)  are only found in vertebrates.

Question 18

Most reptiles inhale by

Accepted Answer

A)  using a positive force pump. 
B)  buccal breathing. 
C)  actively moving. 
D)  creating a negative pressure in the lungs. 
E)  lung ventilation. 
A)  using a positive force pump. 
B)  buccal breathing. 
C)  actively moving. 
D)  creating a negative pressure in the lungs. 
E)  lung ventilation.

Question 19

Which of the following is required for efficient gas exchange across a respiratory organ?

Accepted Answer

A)  A large, dry surface area. 
B)  A thick boundary layer at the respiratory surface. 
C)  A higher concentration of O2 inside the organ. 
D)  A highly vascularised respiratory surface. 
E)  A large volume compared to the surface area. 
A)  A large, dry surface area. 
B)  A thick boundary layer at the respiratory surface. 
C)  A higher concentration of O2 inside the organ. 
D)  A highly vascularised respiratory surface. 
E)  A large volume compared to the surface area.

Question 20

Countercurrent flow in gas exchange

Accepted Answer

A)  is when water and circulatory fluid flow in opposite directions across the respiratory surface. 
B)  is not found in invertebrates. 
C)  is a less-efficient mechanism than co-current flow. 
D)  decreases the efficiency of gas exchange when compared with water flowing in the same direction. 
E)  results in water leaving the gills with a high partial pressure of oxygen. 
A)  is when water and circulatory fluid flow in opposite directions across the respiratory surface. 
B)  is not found in invertebrates. 
C)  is a less-efficient mechanism than co-current flow. 
D)  decreases the efficiency of gas exchange when compared with water flowing in the same direction. 
E)  results in water leaving the gills with a high partial pressure of oxygen.

Exam 23: Gas Exchange in Animals

What is the only mammal bereft of a pleural space, and what is the reason for this unusual modification?

Different respiratory pigments have different affinities for O2. The difference in O2 affinity of human fetal and maternal haemoglobin enables the transfer of O2 from the mother's blood to fetal blood in the placenta. For this to be possible

Protons are unable to pass through the blood-brain barrier, but CO2 can. As such, the chemoreceptors located in the medulla regulate the pH of cerebral interstitial fluid as a reflection of changes in the partial pressure of

Along what kind of gradient do gasses diffuse across membranes?

For crustaceans with gills housed in branchial chambers, ventilation is maintained by

Gas exchange is

Cutaneous gas exchange is

Respiratory pigments include a metallic ion. What is the ion present in haemocyanin, and what is the role of these ions in respiratory pigments?

The presence of surfactant in mammalian lungs

Animals were able to increase in size and become multicellular because of the

Which of the following statements is true?

The metabolic products produced by the tissue of an energetically active mammal enter the bloodstream. What are two of these products and how do they affect the O2 affinity of haemoglobin?

In terms of gas exchange, the evolution of large animals was dependent on

A prerequisite for a terrestrial existence was the development of

Respiratory pigments in animals

Most reptiles inhale by

Which of the following is required for efficient gas exchange across a respiratory organ?

Countercurrent flow in gas exchange

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Different respiratory pigments have different affinities for O₂. The difference in O₂ affinity of human fetal and maternal haemoglobin enables the transfer of O₂ from the mother's blood to fetal blood in the placenta. For this to be possible

Protons are unable to pass through the blood-brain barrier, but CO₂ can. As such, the chemoreceptors located in the medulla regulate the pH of cerebral interstitial fluid as a reflection of changes in the partial pressure of

The metabolic products produced by the tissue of an energetically active mammal enter the bloodstream. What are two of these products and how do they affect the O₂ affinity of haemoglobin?