Question 1

Which of the following best describes the mechanism of breathing in mammals?

Accepted Answer

Negative pressure breathing, where air is drawn into the lungs by expanding the thoracic cavity.

Question 2

What is the primary function of the diaphragm during mammalian inhalation?

Accepted Answer

It contracts and moves downward, increasing thoracic cavity volume.

Question 3

Birds have a highly efficient respiratory system because:

Accepted Answer

Air flows in only one direction through the lungs, and fresh air does not mix with air that has already undergone gas exchange.

Question 4

Which equation correctly represents the chemical reaction that links CO2 concentration to pH in cerebrospinal fluid?

Accepted Answer

$$\mathrm{CO_2$ + H_2O \rightarrow H_2CO_3 \rightarrow $$HCO_3$$^- + H^+}$$

Question 5

If the elasticity of alveoli is lost due to disease, what is the most likely effect on gas exchange?

Accepted Answer

Gas exchange efficiency decreases because alveoli cannot recoil properly, reducing ventilation.

Question 6

During exercise, which of the following best explains how mammals increase their ventilation?

Accepted Answer

Additional muscles in the neck, back, and chest help expand the thoracic cavity.

Question 7

Why do mammals have a lower maximum partial pressure of oxygen ($$P_{O_2$}) in $$their lungs compared to birds?

Accepted Answer

Mammals mix fresh air with oxygen-depleted residual air during inhalation.

Question 8

Which of the following is TRUE about the control of breathing in humans?

Accepted Answer

The medulla oblongata regulates breathing primarily in response to blood carbon dioxide levels and pH.

Question 9

A person begins to hyperventilate (breathe very rapidly) while at rest. What is the immediate effect on blood CO2 and pH?

Accepted Answer

Blood CO2 decreases and pH increases.

Question 10

Which of the following best describes the process of positive pressure breathing in amphibians?

Accepted Answer

Air is forced into the lungs by raising the floor of the oral cavity with the mouth and nostrils closed.

Question 11

What would be the effect of a small hole in the membranes surrounding the lungs?

Accepted Answer

The lung would collapse due to loss of surface tension between the membranes.

Question 12

Which of the following is the correct definition of tidal volume?

Accepted Answer

The volume of air inhaled and exhaled with each normal breath.

Question 13

During a forced exhalation, which muscles are primarily involved in mammals?

Accepted Answer

Rib muscles and additional muscles of the abdomen and chest.

Question 14

Which of the following best explains why birds can fly at higher altitudes than mammals?

Accepted Answer

Birds have a unidirectional airflow system that prevents mixing of fresh and stale air, maintaining a higher $$P_{O_2$}.$$

Question 15

Which of the following is a direct result of increased CO2 in the blood?

Accepted Answer

Decreased blood pH due to formation of carbonic acid.

Question 16

What is the function of the residual volume in the lungs?

Accepted Answer

It prevents the lungs from collapsing by maintaining some air after forced exhalation.

Question 17

Which of the following best describes the role of stretch sensors in the lungs during inhalation?

Accepted Answer

They inhibit further inhalation to prevent overexpansion of the lungs.

Question 18

A drop in blood pH causes an increase in heart rate. What is the function of this control mechanism?

Accepted Answer

To increase blood flow and enhance removal of CO2 from tissues.

Question 19

Which of the following is TRUE about the double membrane surrounding the lungs?

Accepted Answer

Surface tension in the fluid between the layers causes them to stick together, so lung and thoracic cavity volumes change together.

Breathing and Ventilation Mechanisms in Vertebrates

Study Guide - Practice Questions