Question 1

Which of the following best describes the main difference between open and closed circulatory systems, and how does this difference affect blood pressure and flow?

Accepted Answer

Open systems have hemolymph that bathes organs directly, resulting in lower pressure and slower flow compared to closed systems.

Question 2

Which of the following correctly matches a vertebrate group with its heart structure and circulatory circuits?

Accepted Answer

Fish: two-chambered heart, single circuit

Question 3

Which structural feature of arteries allows them to withstand and regulate the high pressure generated by the heart?

Accepted Answer

Thick layers of smooth muscle and elastic tissue

Question 4

As blood moves from arteries to capillaries in the systemic circulation, what happens to blood velocity and total cross-sectional area, and why?

Accepted Answer

Velocity decreases and total area increases because capillaries are numerous and narrow.

Question 5

During systemic circulation, which chamber of the heart receives oxygenated blood from the lungs?

Accepted Answer

Left atrium

Question 6

Why is the left ventricle wall thicker than the right ventricle wall?

Accepted Answer

It pumps blood to the entire body, requiring higher pressure.

Question 7

What is the primary function of the lymphatic system in relation to the circulatory system?

Accepted Answer

To return excess interstitial fluid to the bloodstream

Question 8

Which statement best explains why the electrical signal is delayed at the AV node during the cardiac cycle?

Accepted Answer

To allow the atria to finish contracting and fill the ventricles before ventricular contraction

Question 9

A patient’s blood pressure is measured as 140/90 mmHg. What do these numbers represent?

Accepted Answer

140 mmHg is systolic pressure; 90 mmHg is diastolic pressure

Question 10

Which equation correctly represents cardiac output ($$CO) $$and what does it mean physiologically?

Accepted Answer

$$CO = HR 	imes SV$$

Question 11

A myocardial infarction (heart attack) is most directly caused by which of the following?

Accepted Answer

A blockage of blood flow to heart muscle due to atherosclerosis

Question 12

Which of the following is NOT a way that diving mammals maximize their oxygen stores during long dives?

Accepted Answer

Increasing blood flow to non-essential organs

Question 13

Which of the following best describes the structure and function of hemoglobin?

Accepted Answer

A protein with four subunits, each containing a heme group that binds one oxygen molecule

Question 14

What is the significance of the sigmoidal (S-shaped) oxygen-hemoglobin equilibrium curve?

Accepted Answer

It reflects cooperative binding, allowing efficient oxygen loading and unloading.

Question 15

During vigorous exercise, what happens to the oxygen-hemoglobin equilibrium curve and why?

Accepted Answer

It shifts to the right due to decreased pH and increased CO$$_2$$, facilitating oxygen release to tissues.

Question 16

Which of the following equations correctly represents the formation of bicarbonate from carbon dioxide in red blood cells?

Accepted Answer

$$CO_2 + H_2O$$ \rightarrow H_2CO_3 \rightarrow $$HCO_3^- + H$$^+$$

Question 17

Which of the following best describes the three main forms in which CO$$_2 is $$transported in the blood, and their approximate proportions?

Accepted Answer

As bicarbonate ions (about 70%), bound to hemoglobin (about 20%), dissolved in plasma (about 10%)

Question 18

What is hematocrit, and why is it clinically important?

Accepted Answer

The percentage of red blood cells in blood; it reflects oxygen-carrying capacity.

Question 19

Which of the following best explains why fluid accumulates in the interstitial space outside capillaries?

Accepted Answer

Blood pressure forces fluid out of capillaries, and not all of it is reabsorbed due to osmotic pressure.

Question 20

Which of the following statements about the oxygen equilibrium curve for myoglobin compared to hemoglobin is correct?

Accepted Answer

Myoglobin's curve is hyperbolic and has a higher affinity for oxygen than hemoglobin.

Step-by-Step Guidance for College Biology: Circulation and Blood

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