Life: The Science of Biology

Purves, William K., Sadava, David E., Orians, Gordon H., Heller, H. Craig

Chapter 48

Gas Exchange in Animals - all with Video Answers

Educators

Chapter Questions

Problem 1

Which of the following statements is not true?
a. Respiratory gases are exchanged only by diffusion.
b. Oxygen has a lower rate of diffusion in water than in air.
c. The $\mathrm{O}_{2}$ content of water falls as the temperature of water rises.
d. The amount of $\mathrm{O}_{2}$ in the atmosphere decreases with increasing altitude.
$e .$ Birds have evolved active transport mechanisms to augment their respiratory gas exchange.

Bryan Valdivia

Bryan Valdivia

Numerade Educator

Problem 2

Which statement about the gas exchange system of birds is not true?
a. Respiratory gases are not exchanged in the air sacs.
$b$. It can achieve more complete exchange of $\mathrm{O}_{2}$ from air to blood than the human gas exchange system can.
c. Air passes through birds' lungs in only one direction.
$d .$ The gas exchange surfaces in bird lungs are the alveoli.
$e .$ A breath of air remains in the system for two breathing cycles.

Noah Boudrie

Numerade Educator

Problem 3

Which statement about gas exchange in fish is true?
a. Blood flows over the gas exchange surfaces in a direction opposite to the flow of water.
b. Gases are exchanged across the gill filaments.
c. Ventilation of the gills is tidal in fast swimming fishes.
d. Less work is needed to ventilate gills in warm water than in cold water.
e. The path length for diffusion of respiratory gases is determined by the length of the gill filaments.

Noah Boudrie

Numerade Educator

Problem 4

In the human gas exchange system,
$a$. the lungs and airways are completely collapsed after a forceful exhalation.
$b$. the average $P_{O_{2}}$ concentration of air inside the lungs is always lower than that in the air outside the lungs.
$c$. the $\mathrm{P}_{\mathrm{O}_{2}}$ of the blood leaving the lungs is greater than the $\mathrm{P}_{\mathrm{O}_{2}}$ of the exhaled air.
$d$. the amount of air that is moved per breath during normal, at-rest breathing is termed the total lung capacity. oxygen and carbon dioxide are actively transported across the alveolar and capillary membranes.

Bryan Valdivia

Numerade Educator

Problem 5

Which statement about the human gas exchange system is not true?
a. During inhalation, a subatmospheric pressure exists in the space between the lung and the thoracic wall.
b. Smoking one cigarette can immobilize the cilia lining the airways for hours.
c. The respiratory control center in the medulla responds more strongly to changes in arterial $\mathrm{O}_{2}$ concentration than to changes in arterial $\mathrm{CO}_{2}$ concentration.
d. Without surfactant, the work of breathing is greatly increased.
e. The diaphragm contracts during inhalation and relaxes during exhalation.

Bryan Valdivia

Numerade Educator

Problem 6

The hemoglobin of a human fetus
$a .$ is the same as that of an adult.
$b$. has a higher affinity for $\mathrm{O}_{2}$ than adult hemoglobin has.
$c .$ has only two protein subunits instead of four.
$d$. is supplied by the mother's red blood cells.
$e .$ has a lower affinity for $\mathrm{O}_{2}$ than adult hemoglobin has.

Bryan Valdivia

Numerade Educator

Problem 7

The amount of $\mathrm{O}_{2}$ carried by hemoglobin depends on the $P_{O}$ in the blood. Hemoglobin in active muscles
a. becomes saturated with $\mathrm{O}_{2}$
$b$. takes up only a small amount of $\mathrm{O}_{2}$
$c .$ readily unloads $\mathrm{O}_{2}$
$d$. tends to decrease the $P_{\mathrm{O}_{2}}$ in the muscle tissues.
$e .$ is denatured.

Bryan Valdivia

Numerade Educator

Problem 8

Most $\mathrm{CO}_{2}$ in the blood is carried
$a$. in the cytoplasm of red blood cells.
$b .$ dissolved in the plasma.
$c .$ in the plasma as bicarbonate ions.
$d .$ bound to plasma proteins.
$e .$ in red blood cells bound to hemoglobin.

Bryan Valdivia

Numerade Educator

Problem 9

Myoglobin
$a$. binds $\mathrm{O}_{2}$ at $\mathrm{P}_{\mathrm{O}_{2}}$ values at which hemoglobin is releasing its bound $\mathrm{O}_{2}$
b. has a lower affinity for $\mathrm{O}_{2}$ than hemoglobin does.
$c .$ consists of four polypeptide chains, just as hemoglobin does.
d. provides an immediate source of $\mathrm{O}_{2}$ for muscle cells at the onset of activity.
$e .$ can bind four $\mathrm{O}_{2}$ molecules at once.

Eric Goldman

Numerade Educator

Problem 10

When the level of $\mathrm{CO}_{2}$ in the bloodstream increases,
$a$. the rate of respiration decreases.
$b$. the $\mathrm{pH}$ of the blood rises.
$c .$ the respiratory centers become dormant.
$d$. the rate of respiration increases.
$e .$ the blood becomes more alkaline.

Christina Sorrentino

Christina Sorrentino

Numerade Educator