Question 1

Which of the following best describes the four steps of gas exchange in animals?

Accepted Answer

Ventilation, gas exchange, circulation, cellular respiration

Question 2

Why do large animals require a circulatory system, while small or thin animals like flatworms do not?

Accepted Answer

Diffusion is only efficient over small distances, so large animals need a circulatory system to transport gases and nutrients.

Question 3

Which of the following is a key difference between open and closed circulatory systems?

Accepted Answer

Open systems have hemolymph that is not confined to vessels, while closed systems have blood confined to vessels.

Question 4

In mammals, which structure is responsible for initiating the electrical signal that triggers heart contraction?

Accepted Answer

Sinoatrial (SA) node

Question 5

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

Accepted Answer

$$CO = HR 	imes SV$$

Question 6

What is the main advantage of countercurrent exchange in fish gills?

Accepted Answer

It maintains a large partial pressure difference for oxygen across the entire gill surface.

Question 7

Which of the following best explains why water breathers expend more energy ventilating their respiratory surfaces than air breathers?

Accepted Answer

Water is denser and contains less oxygen than air.

Question 8

Which of the following statements about capillaries is correct?

Accepted Answer

Capillaries are composed of a single layer of endothelial cells, allowing efficient exchange of gases and nutrients.

Question 9

A patient has a defect in their aortic valve, causing blood to flow backward into the left ventricle. What is this condition called?

Accepted Answer

Heart murmur

Question 10

Which of the following best describes the function of the lymphatic system in circulation?

Accepted Answer

It returns excess interstitial fluid to the bloodstream.

Question 11

Which of the following animals is most likely to have a single circulatory circuit and a two-chambered heart?

Accepted Answer

Fish

Question 12

What is the primary reason that hemoglobin is so effective at transporting oxygen in the blood?

Accepted Answer

Hemoglobin binds oxygen efficiently at respiratory surfaces and releases it at tissues.

Question 13

Which of the following best explains why diving mammals can stay underwater for extended periods?

Accepted Answer

They have a high blood to body volume ratio and store oxygen in muscle myoglobin.

Question 14

Which of the following is a correct statement about the partial pressure of gases?

Accepted Answer

Partial pressure is calculated by multiplying the fractional composition of a gas by the total pressure of the mixture.

Question 15

Which of the following best describes the role of baroreceptors in the circulatory system?

Accepted Answer

They detect changes in blood pressure and trigger responses to maintain homeostasis.

Question 16

A person is exercising vigorously. Which of the following changes would you expect in their cardiac output ($$CO$$)?

Accepted Answer

$$CO$$ increases due to an increase in both heart rate ($$HR) $$and stroke volume ($$SV).$$

Question 17

Which of the following is a unique adaptation of the avian (bird) respiratory system compared to mammals?

Accepted Answer

Birds have unidirectional airflow through their lungs, allowing gas exchange during both inhalation and exhalation.

Question 18

Which of the following best explains why capillaries are 'leaky' and how this is compensated for in the body?

Accepted Answer

Capillaries allow some fluid to leave due to hydrostatic pressure, but most is returned by osmotic pressure and the lymphatic system collects the rest.

Question 19

Which of the following is a correct sequence of blood flow through the mammalian heart during one complete cardiac cycle?

Accepted Answer

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

Circulation and Gas Exchange in Animals

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