Chapter 21. 21·12–21·17 The respiratory system enables gas exchange in animals.

Show What You Know - Self Quiz

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Instructions

Check your understanding of concepts from 21·12–21·17 The respiratory system enables gas exchange in animals by answering the following questions.

1.

1. The two primary gases involved in gas exchange are:

N₂ and CO₂.

CO₂ and CO.

O₂ and CO₂.

O₂ and HCO₃^-.

O₂ and N₂.

Correct. (See section 21·12 Oxygen and carbon dioxide must get into and out of the circulatory system.)

Incorrect. (See section 21·12 Oxygen and carbon dioxide must get into and out of the circulatory system.)

2.

2. Why is there less air pressure at higher elevations?

Gravity decreases as one moves away from the earth’s center, so air tends to drift away at higher elevations.

Air cannot "hold on" as well to the earth when it is covered by snow.

There is less atmosphere “pushing down” from above as one gets higher in elevation.

Higher elevations are colder, and colder environments hold fewer air molecules.

There are more oxygen particles tightly packed together and they cannot move.

Correct. (See section 21·13 Oxygen is transported while bound to hemoglobin.)

Incorrect. (See section 21·13 Oxygen is transported while bound to hemoglobin.)

3.

3. Why is countercurrent exchange of oxygen in fish gills so efficient?

It only requires 1 ATP per oxygen molecule to transport oxygen quickly from the water into the blood.

Fish gills and their lamellae channel the oxygen-laden water only to parts of the fish that need oxygen.

It maintains a concentration gradient between the water and the bloodstream for the entire time that the water and blood vessel are in close contact.

The disk shape of the gill lamellae ensure that oxygen being absorbed is separated from carbon dioxide that is being released into passing water.

The fish heart moves blood so rapidly through the gills that very little oxygen is lost during the gas exchange process.

Correct. (See section 21·14 Gas exchange takes place in the gills of aquatic vertebrates.)

Incorrect. (See section 21·14 Gas exchange takes place in the gills of aquatic vertebrates.)

4.

4. In human lungs, the windpipe branches into two bronchi. The bronchi then branch several times to become:

bronchioles.

lungs.

alveoli.

the trachea.

the larynx.

Correct. (See section 21·15 Respiratory systems of terrestrial vertebrates move oxygen-rich air into and carbon-dioxide-rich air out of the lungs.)

Incorrect. (See section 21·15 Respiratory systems of terrestrial vertebrates move oxygen-rich air into and carbon-dioxide-rich air out of the lungs.)

5.

5. Which of the following best describes the inhalation process?

The diaphragm and intercostal muscles contract. The diaphragm bends upward in a dome shape, compressing the rib cage. This causes the partial pressure of oxygen in the chest cavity to increase, pushing oxygen into the lungs.

The diaphragm and intercostal muscles contract. The diaphragm is pulled lower, causing the rib cage to expand. The rapid increase in volume of the chest cavity causes air to be sucked into the lungs.

The chest cavity expands, pushing down the diaphragm and creating negative pressure. This negative pressure causes the lungs to expand and draw in air.

The diaphragm and intercostal muscles contract. The diaphragm is pulled lower, compressing the rib cage. The rapid decrease in volume of the chest cavity causes air to be sucked into the lungs.

The diaphragm and intercostal muscles relax. The diaphragm is pulled lower, causing the rib cage to expand. The rapid increase in volume of the chest cavity causes air to be sucked into the lungs.

Correct. (See section 21·16 Birds have unusually efficient respiratory systems.)

Incorrect. (See section 21·16 Birds have unusually efficient respiratory systems.)

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