Question 1

Which of the following best describes the function of the red feathery appendages seen in the first image of the provided materials?

Accepted Answer

They are specialized structures for gas exchange, allowing O2 to diffuse from water into blood vessels and CO2 to diffuse from blood into water.

Question 2

In animals with a simple body plan, such as the moon jelly Aurelia and the planarian Dugesia shown in the images, how do small molecules like O2 and CO2 move between cells and their surroundings?

Accepted Answer

By diffusion across the gastrovascular cavity.

Question 3

Which of the following is a key difference between open and closed circulatory systems, as illustrated in the images and text?

Accepted Answer

Open systems use hemolymph that bathes organs directly, while closed systems confine blood to vessels and are more efficient at transporting fluids.

Question 4

Referencing the diagram of vertebrate circulatory systems, which animal has a single circulation pattern and a two-chambered heart?

Accepted Answer

Fish

Question 5

Which equation correctly represents cardiac output ($$CO) in $$humans?

Accepted Answer

$$CO = HR 	imes SV$$

Question 6

What is the primary function of the sinoatrial (SA) node in the mammalian heart?

Accepted Answer

It sets the rate and timing at which cardiac muscle cells contract, acting as the pacemaker.

Question 7

Which of the following statements about blood vessel structure is correct?

Accepted Answer

Arteries have thicker walls than veins to accommodate the high pressure of blood pumped from the heart.

Question 8

During exercise, a runner’s face becomes flushed. Which physiological process is most responsible for this change?

Accepted Answer

Vasodilation

Question 9

Which of the following best explains the movement of fluid across capillary walls?

Accepted Answer

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

Question 10

Which blood component is primarily responsible for transporting oxygen?

Accepted Answer

Erythrocytes (red blood cells)

Question 11

A patient is diagnosed with atherosclerosis. Which of the following best describes this condition?

Accepted Answer

It is caused by the buildup of plaque deposits within arteries, increasing the risk of heart attack and stroke.

Question 12

Which respiratory pigment is found in vertebrates and is responsible for binding and transporting oxygen?

Accepted Answer

Hemoglobin

Question 13

What is the effect of a drop in blood pH on hemoglobin’s affinity for oxygen, known as the Bohr shift?

Accepted Answer

Hemoglobin retains less O2 at lower pH, releasing more oxygen to tissues.

Question 14

Which of the following is the main mechanism by which CO2 is transported in the blood?

Accepted Answer

As bicarbonate ions ($$HCO_3$$^-$$) in plasma

Question 15

Which of the following best describes the path of a red blood cell through the human heart, pulmonary circuit, and systemic circuit?

Accepted Answer

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

Question 16

Which of the following is a function of the lymphatic system in relation to the circulatory system?

Accepted Answer

It returns interstitial fluid back to the blood and helps in body defense.

Question 17

Which of the following is true regarding the exchange of gases in the lungs and tissues of humans?

Accepted Answer

O2 diffuses from alveoli into blood, and CO2 diffuses from blood into alveoli; in tissues, O2 diffuses from blood into cells and CO2 from cells into blood.

Question 18

Which of the following is a real-world consequence of weakened valves in leg veins, as shown in the images?

Accepted Answer

Varicose veins, which are visibly swollen veins under the skin.

Question 19

Which of the following best describes the advantage of countercurrent exchange in fish gills?

Accepted Answer

It maximizes O2 uptake by maintaining a gradient where blood always encounters water with higher O2 partial pressure.

Circulation and Gas Exchange in Animals

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