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.

Accepted Answer

Gas exchange refers to the process of moving oxygen (O2) and carbon dioxide (CO2) between the environment and the cells, specifically the mitochondria, where cellular respiration occurs.

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.

Accepted Answer

C

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.

Accepted Answer

D

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.

Accepted Answer

The partial pressure of oxygen decreases with increasing altitude because the overall atmospheric pressure decreases, leading to a decrease in the pressure exerted by oxygen specifically. The proportion of oxygen in the air (about 21%) remains relatively constant with altitude.

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.

Accepted Answer

The rate of diffusion of a gas across a membrane is primarily dependent on the partial pressure gradient, as described by Fick's law of diffusion. This principle states that the rate of diffusion is directly proportional to the difference in partial pressures across the membrane.

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.

Accepted Answer

A highly vascularised respiratory surface ensures efficient gas exchange by providing a large surface area for diffusion and a close proximity of blood to the respiratory surface for the exchange of gases.

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.

Accepted Answer

Active and endothermic animals have the highest metabolic rates, requiring efficient gas exchange systems to meet their oxygen demands and remove carbon dioxide efficiently. This necessitates a large surface area relative to their size for gas exchange.

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.

Accepted Answer

The development of mechanisms for efficient gas exchange and internal transport allowed animals to grow larger and become multicellular by effectively distributing oxygen and nutrients throughout their bodies.

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.

Accepted Answer

Cutaneous gas exchange refers to the process of exchanging gases through the skin and is characteristic of annelids, such as earthworms, which utilize their moist skin as a respiratory surface for the exchange of oxygen and carbon dioxide with their environment.

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.

Accepted Answer

Gills, which are outgrowths of the body surface, serve as the primary site for gas exchange in many aquatic invertebrates. This structure allows for a large surface area in contact with the surrounding water, facilitating the diffusion of oxygen into the body and carbon dioxide out.

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.

Accepted Answer

Scaphognathites are specialized appendages in crustaceans that function to create water currents for ventilation in the branchial chambers where the gills are located, facilitating gas exchange.

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.

Accepted Answer

Countercurrent flow is a mechanism where water and blood flow in opposite directions across the respiratory surface, maximizing the gradient for gas exchange and increasing efficiency.

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.

Accepted Answer

Countercurrent gas exchange involves blood flowing in the opposite direction to water over the gills, allowing for a gradient where blood with lower O2 meets water with higher O2, maximizing oxygen uptake.

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.

Accepted Answer

The description of the gills with many filaments and lamellae, along with the need for continuous swimming, suggests a fish that relies on ram ventilation, like a tuna. Tuna are known for their high-speed swimming and require continuous movement to pass water over their gills for oxygen exchange.

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.

Accepted Answer

Gills are thin-walled and collapse in air, reducing their surface area and making them ineffective for gas exchange outside of water.

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.

Accepted Answer

An internally housed gas-exchange system, such as lungs, is crucial for terrestrial existence as it allows organisms to efficiently exchange gases in a non-aquatic environment.

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.

Accepted Answer

Amphibians are known for their ability to absorb oxygen through their skin, which is a significant part of their respiratory system. This skin must remain moist to facilitate gas exchange effectively. The statement about losing "CO₂" through their gills seems to be a typographical error, but it likely refers to losing carbon dioxide (CO2) through their skin or gills, which is a common process in amphibians.

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.

Accepted Answer

Lungs in vertebrates developed as outgrowths of the gut, allowing for the direct exchange of gases with the external environment through the digestive tract.

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.

Accepted Answer

Air contains a higher concentration of O₂ compared to water, making tidal ventilation effective for large, air-breathing animals.

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.

Accepted Answer

Most reptiles inhale by creating a negative pressure in the lungs, which draws air into the lungs. This is different from methods like buccal breathing, which is more characteristic of amphibians.

Quiz 23: Gas Exchange in Animals

Gas exchange is

Which of the following statements is true?

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

Increasing altitude has which of the following effects on air?

The rate of diffusion of a gas across a membrane is

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

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

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

Cutaneous gas exchange is

In aquatic invertebrates

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

Countercurrent flow in gas exchange

Countercurrent gas exchange

Gills do not function well in air because

A prerequisite for a terrestrial existence was the development of

Amphibians

Vertebrate lungs

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

Most reptiles inhale by