Question 1

Which of the following best describes the primary function of the circulatory system in multicellular organisms?

Accepted Answer

To create an 'internal sea' that transports food, oxygen, and wastes close to cells, enabling efficient exchange.

Question 2

Which of the following is NOT a major component of a typical animal circulatory system?

Accepted Answer

A gland for hormone secretion

Question 3

In insects, the heart is a modified blood vessel that pumps hemolymph. What is the main difference between hemolymph and blood in vertebrates?

Accepted Answer

Hemolymph acts as both blood and interstitial fluid, bathing tissues directly.

Question 4

Which statement correctly compares open and closed circulatory systems?

Accepted Answer

Closed systems confine blood to vessels, allowing for higher pressure and more efficient transport.

Question 5

Trace the path of a drop of blood starting in the right atrium of a human heart. Which sequence correctly follows its journey?

Accepted Answer

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

Question 6

Which heart valve prevents backflow of blood from the right ventricle to the right atrium?

Accepted Answer

Tricuspid valve

Question 7

During the cardiac cycle, what does the systolic pressure measure?

Accepted Answer

The maximum pressure in the arteries during ventricular contraction.

Question 8

A patient has a blood pressure reading of 145/95 mmHg. What condition does this indicate, and what is a likely consequence if left untreated?

Accepted Answer

Hypertension; increased risk of heart disease and stroke.

Question 9

Which structure in the heart acts as the primary pacemaker, initiating electrical impulses for contraction?

Accepted Answer

Sinoatrial (SA) node

Question 10

If the SA node fails, which structure can take over as a secondary pacemaker to maintain heart rhythm?

Accepted Answer

Atrioventricular (AV) node

Question 11

Which blood component is responsible for carrying oxygen from the lungs to tissues, and what molecule enables this function?

Accepted Answer

Red blood cells; hemoglobin

Question 12

A person with type A blood receives a transfusion of type B blood. What is the most likely outcome?

Accepted Answer

Agglutination and immune response due to anti-B antibodies attacking type B cells.

Question 13

Which process is regulated by negative feedback involving erythropoietin?

Accepted Answer

Production of red blood cells in response to low oxygen levels.

Question 14

Which of the following best explains why veins appear blue under the skin, even though venous blood is dark red?

Accepted Answer

Subcutaneous fat absorbs low-frequency light, allowing blue wavelengths to reflect back to the viewer.

Question 15

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

Accepted Answer

$$CO = HR 	imes SV$$

Question 16

Which blood vessel type is primarily responsible for exchange of nutrients and wastes between blood and tissues?

Accepted Answer

Capillaries

Question 17

A patient develops elephantiasis, resulting in severe swelling of the legs. What is the underlying cause?

Accepted Answer

Blocked lymphatic vessels due to parasitic roundworm infection.

Question 18

Which of the following best describes the role of platelets in blood clotting?

Accepted Answer

Platelets form a plug and help convert fibrinogen to fibrin, creating a mesh that traps blood cells.

Question 19

Which lymphatic organ is most similar to a lymph node but also destroys old red blood cells?

Accepted Answer

Spleen

Chapter 33: Circulation – Structure and Function of Circulatory Systems

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