Deck 23: Gas Exchange in Animals

Question 1

Gas exchange is

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.

Answer 1

the movement of O₂ and CO₂ between the environment and mitochondria.

Question 2

Which of the following statements is true?

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.

Answer 2

An increase in temperature decreases the capacitance of CO₂ and O₂ in water.

Question 3

Air and water have very different properties as respiratory media. Which of the following is CORRECT?

A) The solubility of O₂ in air and water is the same.
B) O₂ is more soluble in water than CO₂.
C) Compared to water, air provides a greater resistance to diffusion of both O₂ and CO₂.
D) The capacitance of O₂ and CO₂ in air is the same.
E) The capacitance of air for CO₂ is greater than for O₂.

Answer 3

The capacitance of O₂ and CO₂ in air is the same.

Question 4

Increasing altitude has which of the following effects on air?

A) The proportion of oxygen decreases.
B) The partial pressure of oxygen decreases.
C) The partial pressure of oxygen increases.
D) The concentration of oxygen increases.
E) The proportion of oxygen increases.

Question 5

The rate of diffusion of a gas across a membrane is

A) dependent on a partial pressure gradient.
B) the same for all types of membranes.
C) independent of membrane thickness.
D) proportional to the thickness of the membrane.
E) All of the answers are correct.

Question 6

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

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 7

In general, you would expect to find the greatest surface area (relative to size) for gas exchange in animals that are

A) ectothermic.
B) active and endothermic.
C) sedentary and endothermic.
D) vertebrates.
E) invertebrates.

Question 8

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

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 9

Cutaneous gas exchange is

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 10

In aquatic invertebrates

A) ventilation is always achieved by the beating of the swimming appendages.
B) gas exchange occurs via papulae in most crustaceans.
C) gills are rarely located in chambers.
D) ventilation is essential for gas exchange in papulae.
E) gills are outgrowths of the body surface.

Question 11

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

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

Question 12

Countercurrent flow in gas exchange

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.

Question 13

Countercurrent gas exchange

A) is characteristic of terrestrial organisms because O₂ is more available in air than water.
B) involves circulatory fluid with a high partial pressure of O₂ leaving the gill filament encountering water with a higher partial pressure of O₂ entering the filament.
C) occurs in sponges due to choanocytes lining the surface.
D) is more efficient than co-current exchange because water and circulatory fluid reach equilibrium at a partial pressure of O₂ significantly lower than that of water.
E) is not possible for fish because their gill chambers are full of lamellae.

Question 14

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

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

Question 15

Gills do not function well in air because

A) they have a large surface area.
B) they are heavily chitinised.
C) they are thin-walled and heavy.
D) they rely on muscular action.
E) surface tension would increase and decrease gas exchange.

Question 16

A prerequisite for a terrestrial existence was the development of

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

Amphibians

A) use only their gills for gas exchange.
B) ventilate their lungs continuously using negative pressure.
C) rarely use their skin for gas exchange.
D) absorb oxygen through their skin and loose CO₂ through their gills.
E) characteristically absorb O₂ in the lungs and lose carbon dioxide through the skin.

Question 18

Vertebrate lungs

A) are outgrowths of the body wall, like gills.
B) developed as outgrowths of the gut.
C) are found in the Japanese weather loach.
D) developed from gas bladders in fish.
E) are typically used as secondary respiratory surfaces because most vertebrates respire primarily across their skin.

Question 19

Tidal ventilation is feasible in large, air-breathing animals because

A) O₂ is more available in air than water.
B) O₂ is more available in water than air.
C) it enables countercurrent gas exchange.
D) it increases the partial pressure of O₂ in the lungs.
E) it increases the partial pressure of O₂ in the lung.

Question 20

Most reptiles inhale by

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

Question 21

Mammalian lungs

A) are basically a dense capillary network encased by a thin epithelial layer.
B) provide a small diffusion distance between air and blood at the exchange surface.
C) are a mass of branching ducts and cupped-shaped chambers.
D) have gas exchange in alveolar ducts.
E) All of the answers are correct.

Question 22

The presence of surfactant in mammalian lungs

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 23

Air sacs in birds

A) function as lungs.
B) provide additional gas exchange surfaces.
C) are the primary sites of gas exchange.
D) facilitate efficient air movement in the lungs.
E) direct countercurrent air flow into the lungs.

Question 24

Which of the following is used by birds during respiration?

A) Countercurrent exchange.
B) Co-current exchange.
C) Cross-current exchange.
D) Large air capillaries.
E) An aspirating pump to create negative pressure in the lung.

Question 25

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?

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

Question 26

The book lung in spiders and scorpions contains

A) numerous horizontal air spaces.
B) a spiracle that is connected to the outside air.
C) an arrangement that brings haemolymph into close contact with air.
D) a large surface area for gas exchange.
E) All of the answers are correct.

Question 27

Respiratory pigments in animals

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 28

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

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.

Question 29

Animals use O₂ and CO₂ (pH) levels to regulate ventilation. Which of the following is CORRECT?

A) Water breathers primarily regulate ventilation in response to changes in CO₂ because their internal levels of CO₂ are very similar to water.
B) Water breathers primarily regulate ventilation in response to changes in CO₂ because O₂ is readily available from water.
C) Air breathers primarily regulate ventilation in response to changes in CO₂ because their internal levels of CO₂ are higher than for air.
D) Water breathers primarily regulate ventilation in response to O₂ changes as the level of O₂ in water is low.
E) Air breathers primarily regulate ventilation in response to changes in O₂ because O₂ is readily available from air.

Question 30

In mammals

A) lungs are stiff but have high compliance.
B) positive pressure in the pleural cavity prevents the lung from collapsing.
C) inspiration is an active muscular process.
D) inspiration is achieved with a positive pressure.
E) lungs are in a cavity within the abdomen.

Question 31

The Haldane effect

A) relates to the effect of CO₂ concentration on acid-base homeostasis.
B) is a property of haemoglobin where oxygenated blood have the ability to carry more CO₂.
C) is not relevant to invertebrates.
D) means that the more deoxygenated the haemoglobin, the better it binds with oxygen.
E) means that the more deoxygenated the haemoglobin, the better it binds with CO₂.

Question 32

Carotid bodies are

A) organs located in the medulla region of the brain.
B) small organs located in arteries which are sensitive to oxygen levels.
C) chemoreceptors which respond to H⁺ ion concentration.
D) central chemoreceptors which contain neurotransmitters which are released in response to changes in the partial pressure of oxygen.
E) organs with a primary function to transmit information from the central nervous system to reflect ventilation requirements.

Question 33

The chloride shift associated with the transport of CO₂ in mammals

A) allows large amounts of hydrogen carbonate to be exchanged between erythrocytes and plasma.
B) maintains the electrical balance between plasma and erythrocytes.
C) requires the movement of Cl^- ions into the erythrocyte in lungs to enable the diffusion of CO₂ out of the erythrocyte.
D) is necessary to balance the H⁺ ions produced from the dissociation of H₂CO₂.
E) All of the answers are correct.

Question 34

If you found an unknown animal with external gills, it most likely would be

A) a sea anemone.
B) a cricket.
C) a salamander.
D) a shark.
E) a cockroach.

Question 35

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

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 36

In water animals, the direction in which water and blood flow relative to one another

A) does not affect the efficiency of gas exchange.
B) gives rapid equilibration dependent only on the surface area of contact.
C) provides efficiency dependent of the type of ventilation.
D) achieves greater efficiency by countercurrent flow.
E) achieves greater efficiency by co-current flow.

Question 37

Along what kind of gradient do gasses diffuse across membranes?

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

Question 38

Many small organisms meet their O₂ requirements by gas diffusion across their membranes. What is a simple, effective method for replenishing O₂ levels in a small organism's immediate environment?

A) Increase the O₂ levels in the boundary layer.
B) Decrease metabolic rates to decrease O₂ use.
C) Decrease the PO₂ pressure gradient across the boundary layer.
D) Decrease the partial pressure gradient for diffusion.
E) Mix and/or replace water in the boundary layer surrounding the organism.

Question 39

An animal in distress is having trouble breathing. Closer inspection reveals it appears to have a punctured thoracic wall. The reason for the animals distress is therefore

A) a thorax embolism.
B) a pleural cavity.
C) a collapsed lung.
D) lack of lung expiration.
E) a passive embolar cavitation.

Question 40

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

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.

Question 41

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

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 42

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?

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 43

In relation to gas exchange, what is the term given to the process that transports O₂ from the site of gas exchange to cells?

A) Perfusion
B) Convection
C) Ventilation
D) Diffusion
E) Cohesion

Question 44

An unknown fish is analysed and found to be devoid of both buccal and opercular muscle systems, but has powerful locomotive musculature. This fish must therefore ventilate its gills by

A) Cutaneous respiration
B) Ram ventilation
C) Simple gill ventilation
D) Chambered gill respiration
E) Metabolic oxygenation

Question 45

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

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