Question 1

Which of the following best explains why diffusion alone is insufficient for transporting substances in large multicellular organisms?

Accepted Answer

Diffusion is only efficient over microscopic distances because the time required increases with the square of the distance: $$t \propto d^2$.

Question 2

In the context of exchange surfaces, which adaptation would most likely increase the efficiency of gas exchange in aquatic animals like the axolotl?

Accepted Answer

Increasing the surface area of the gills through feathery extensions.

Question 3

Which of the following statements about gastrovascular cavities is correct?

Accepted Answer

They combine the functions of digestion and distribution of substances throughout the body.

Question 4

What is the primary difference between open and closed circulatory systems?

Accepted Answer

In open systems, the circulatory fluid (hemolymph) is not always confined to vessels, while in closed systems, blood remains within vessels.

Question 5

Which of the following best describes the function of capillaries in the vertebrate circulatory system?

Accepted Answer

They serve as exchange vessels, allowing for the transfer of gases, nutrients, and wastes between blood and tissues.

Question 6

In the single circulation system of fish, what is a major limitation compared to double circulation systems?

Accepted Answer

Blood pressure drops significantly after passing through the gill capillaries, limiting efficient delivery to body tissues.

Question 7

Why is the left ventricle of the mammalian heart more muscular than the right ventricle?

Accepted Answer

It must generate higher pressure to pump blood throughout the systemic circuit.

Question 8

During which phase of the cardiac cycle are all heart valves closed and the volume of blood in the ventricles remains constant?

Accepted Answer

Isovolumetric contraction

Question 9

Which equation correctly represents cardiac output ($$CO) in $$terms of heart rate ($$HR) $$and stroke volume ($$SV$$)?

Accepted Answer

$$CO = HR 	imes SV$$

Question 10

A patient’s electrocardiogram (ECG) shows an abnormally prolonged QRS complex. What does this most likely indicate?

Accepted Answer

There is a problem with ventricular depolarization, possibly due to a conduction block.

Question 11

Which of the following best explains why endothermic mammals benefit from a four-chambered heart?

Accepted Answer

It allows complete separation of oxygen-rich and oxygen-poor blood, supporting higher metabolic rates.

Question 12

Which of the following is true regarding the direction of blood flow in arteries and veins?

Accepted Answer

Arteries carry blood away from the heart, while veins carry blood toward the heart.

Question 13

Which of the following would most likely result if the chordae tendineae in the heart were damaged?

Accepted Answer

Atrioventricular valves could invert during ventricular contraction, leading to backflow of blood.

Question 14

Which phase of the cardiac cycle is associated with the S2 ('dub') heart sound?

Accepted Answer

Isovolumetric relaxation, when the semilunar valves close

Question 15

If the pressure in the left ventricle exceeds the pressure in the aorta, which valve state is most likely?

Accepted Answer

The aortic semilunar valve is open, allowing blood to flow into the aorta.

Question 16

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

Accepted Answer

It acts as the primary pacemaker, initiating the electrical impulses that set the heart rate.

Question 17

Which of the following is a correct sequence of blood flow through the mammalian heart and major vessels, starting from the right atrium?

Accepted Answer

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

BIO 102 Chapter 42 Part 1 A

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