Question 1

Which of the following best describes the main difference between open and closed circulatory systems?

Accepted Answer

Open circulatory systems use hemolymph that bathes organs directly, while closed circulatory systems confine blood to vessels.

Question 2

A fish has a single circulation system. What is a consequence of this arrangement?

Accepted Answer

Blood pressure drops significantly after passing through the gill capillaries, resulting in slower delivery to body tissues.

Question 3

Which of the following is a function of precapillary sphincters in capillary beds?

Accepted Answer

They regulate blood flow into capillary beds by constricting or relaxing.

Question 4

In mammals, which chamber of the heart receives oxygen-rich blood from the lungs?

Accepted Answer

Left atrium

Question 5

Which of the following equations correctly represents cardiac output ($$CO$$)?

Accepted Answer

$$CO = HR 	imes SV$$

Question 6

A patient has a blood pressure reading of 140/90 mm Hg. What do these numbers represent?

Accepted Answer

140 mm Hg is the systolic pressure, and 90 mm Hg is the diastolic pressure.

Question 7

Which of the following best explains why blood flow is slowest in the capillaries?

Accepted Answer

The total cross-sectional area of capillaries is much greater than that of arteries or veins.

Question 8

Which of the following is a correct sequence for the path of a red blood cell through the human heart and lungs?

Accepted Answer

Right atrium → right ventricle → pulmonary artery → lungs → left atrium → left ventricle → aorta

Question 9

Which of the following statements about the Bohr shift is correct?

Accepted Answer

A decrease in blood pH lowers hemoglobin’s affinity for oxygen, enhancing oxygen unloading in tissues.

Question 10

Which of the following is a major advantage of a four-chambered heart in mammals and birds?

Accepted Answer

It completely separates oxygen-rich and oxygen-poor blood, allowing efficient oxygen delivery to tissues.

Question 11

Which of the following best describes the role of the lymphatic system in relation to the circulatory system?

Accepted Answer

It returns excess interstitial fluid to the bloodstream and helps in immune defense.

Question 12

Which of the following is true regarding the exchange of gases in the alveoli of the lungs?

Accepted Answer

Oxygen diffuses from the alveoli into the blood, while carbon dioxide diffuses from the blood into the alveoli.

Question 13

Which of the following is a function of platelets in the blood?

Accepted Answer

They are involved in blood clotting by forming a platelet plug and releasing clotting factors.

Question 14

Which of the following best explains why obtaining oxygen from water is more challenging than from air?

Accepted Answer

Water contains less oxygen per unit volume than air, and oxygen diffuses more slowly in water.

Question 15

Which of the following is the main respiratory pigment in most vertebrates, and what is its oxygen-binding component?

Accepted Answer

Hemoglobin; iron

Question 16

Which of the following best describes the function of the sinoatrial (SA) node in the heart?

Accepted Answer

It acts as the pacemaker, setting the rate and timing of cardiac muscle contraction.

Question 17

Which of the following equations describes the relationship between blood pressure, cardiac output, and peripheral resistance?

Accepted Answer

$$BP = CO 	imes PR$$

Question 18

Which of the following is a correct statement about the movement of fluids across capillary walls?

Accepted Answer

Fluid moves out of capillaries at the arterial end due to higher blood pressure, and into capillaries at the venous end due to higher osmotic pressure.

Question 19

Which of the following is a real-life example of the importance of the Bohr shift?

Accepted Answer

During intense exercise, increased CO2 production lowers blood pH, causing hemoglobin to release more O2 to active muscles.

Circulation and Gas Exchange: Structure and Function of Circulatory Systems

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