Body Fluids and Circulation - NEET Important Questions

The Class 11 chapter ‘Body Fluids and Circulation’ covers concepts like anatomy of the heart, circulatory pathways, cardiac activity, lymph, blood and blood vessels. Here, let’s have a glance at some important MCQs from this chapter.

1. Match the following blood proteins with their appropriate functions

1. A-2, B-1, C-4, D-3
2. A-3, B-2, C-4, D-1
3. A-4, B-1, C-2, D-3
4. A-4, B-3, C-2, D-1

Answer: c. A-4, B-1, C-2, D-3

Discussion:

• Albumins are proteins which help in maintaining the osmotic balance of the blood.
• Globulins are primarily involved in the defence mechanisms of the body.
• Fibrinogens are the proteins which initiate the blood clotting process, thereby preventing loss of blood from the body.
• Haemoglobin is responsible for the transportation of oxygen in the blood.

2. Which among the following is correct?

1. Serum = plasma – albumins
2. Serum = plasma – clotting factors
3. Serum = plasma – globulins
4. Serum = plasma + albumins

Answer: b. Serum = plasma – clotting factors

Discussion: Plasma is the straw-coloured fluid found in the blood. About 90% of plasma is water and the rest is made up of proteins, ions and other minerals. Plasma without clotting factors is called serum.

Serum = plasma – clotting factors

3. The reason why mature human RBCs cannot divide is

1. Because they carry oxygen
2. Because they are present in the bloodstream
3. Because they lack nucleus
4. Because they are biconcave in shape

Answer: c. Because they lack nucleus

Discussion: Red blood cells (RBCs) or erythrocytes are cells which are responsible for the transportation of oxygen and carbon dioxide. They have a characteristic biconcave shape. Erythropoiesis is the process of maturation of RBCs. One of the steps in erythropoiesis includes extrusion of nucleus from RBCs. Thus, a mature human RBC lacks a nucleus. The absence of a nucleus means no cell division and such a cell lacks any kind of metabolism.

4. Find the correct statement for WBCs

1. Can squeeze through blood capillaries
2. Produced only in the thymus
3. Do not contain a nucleus
4. They carry oxygen

Answer: a. Can squeeze through blood capillaries

Discussion: White blood cells are part of the body’s immune system. They help the body fight infections and other diseases, and they do not carry oxygen. The WBCs are capable of squeezing themselves through the walls of the capillaries. The damage done during this process is easily repaired.

WBCs are produced in the bone marrow. T-lymphocyte, which is a type of WBC, is also produced in the bone marrow, but gets matured in the thymus. Unlike mature RBCs, WBCs contain nuclei.

5. Which of the following statements is correct?

1. Clotting factors are activated by the damaged tissue outside the blood vessel only
2. Prothrombin is the inactive form of thrombin that is present in the plasma
3. The platelets outside the damaged blood vessel activate a cascade of clotting factors
4. Thrombokinase converts prothrombin to fibrin

Answer: b. Prothrombin is the inactive form of thrombin that is present in the plasma

Discussion: When there is a tissue injury that results in a cut in a blood vessel, the damaged tissue outside the blood vessel as well as the platelets inside the damaged blood vessel activate a cascade of clotting factors.

Prothrombin is the inactive form of thrombin that is present in the plasma. Thrombokinase converts prothrombin to active thrombin which in turn activates fibrinogen to fibrin. All these clotting factors help in blood coagulation.

6. Assertion: The arteries are not collapsible when they are empty

Reason: Arteries are situated deeply in the body

1. Both the assertion and reason are true and the reason is the correct explanation for the assertion
2. Both the assertion and reason are true but the reason is not the correct explanation for the assertion
3. Assertion is true but the reason is false
4. Both the assertion and reason are false

Answer: b. Both the assertion and reason are true but the reason is not the correct explanation for the assertion

Discussion: The arteries and veins have 3 layers in their walls – tunica externa, tunica media and tunica interna from outwards to inwards respectively. The middle layer, tunica media is thicker in the arteries than in the veins. There are more muscle fibres in the tunica media layer of the arteries than in the veins. Also, the thick muscular wall of arteries makes them non-collapsible even when they are empty. But the veins are collapsible as they have thin walls.

Arteries carry oxygenated blood under considerable pressure. Any damage to these blood vessels can result in immediate blood loss. Therefore, arteries are deeply located in the body to prevent any damage from outside. The veins, on the other hand, are superficially situated as the blood flows with considerably low pressure in them than in the arteries.

7. Which of the following statements are incorrect about the veins?

Statement 1: Veins usually carry oxygenated blood

Statement 2: Veins carry blood from different organs of the body to the heart

Statement 3: Pulmonary vein is an exception as it carries deoxygenated blood

1. Statements 1 and 2 are incorrect
2. Statements 2 and 3 are incorrect
3. Statements 1 and 3 are incorrect
4. All the statements are incorrect

Answer: c. Statements 1 and 3 are incorrect

Discussion: Veins are the blood vessels that usually carry deoxygenated blood. They carry blood from different organs of the body to the heart. The pulmonary vein is an exception as it carries oxygenated blood to the heart.

8. The layer in the wall of the heart which contains a fluid that protects the heart from shocks and mechanical injuries is known as

1. Pericardium
2. Myocardium
3. Endocardium
4. Both A and C

Answer: a. Pericardium

Discussion: The pericardium is the outermost layer which is a two-layered sac having an outer parietal pericardium and visceral pericardium. In between the parietal and visceral pericardium, there is a cavity called the pericardial cavity. This cavity contains the pericardial fluid which protects the heart from shocks and mechanical injuries.

9. The circulation of blood between the heart and lungs is called ⸻

1. Pulmonary circulation
2. Systemic circulation
3. Double circulation
4. Coronary circulation

Answer: a. Pulmonary circulation

Discussion: Pulmonary circulation is the movement of blood between the heart and lungs. Here, the deoxygenated blood is pumped from the right ventricle to the lungs through the pulmonary artery for oxygenation. After oxygenation, the oxygenated blood returns to the left atrium of the heart through the pulmonary vein.

Systemic circulation is the movement of blood between the heart and different parts of the body.

10. Which one of the following statements is correct?

1. Valves are absent between pulmonary veins and left atrium
2. Semilunar valves are present between right atria and right ventricle
3. Mitral valve has 3 cusps which prevent the backflow of blood
4. There is no valve between ventricle and aorta

Answer: a. Valves are absent between pulmonary veins and left atrium

Discussion: The pulmonary veins carry the oxygenated blood from the lungs to the left atrium. They do not have valves because the pressure exerted by the heart is strong enough to keep the blood flowing in one direction.

Semilunar valves are pocket-like structures attached at the point at which the pulmonary artery and the aorta leave the ventricles. The mitral valve is a bicuspid valve which consists of 2 cusps that prevent the backflow of blood from the left ventricle to the left auricle.

11. Match the following

1. A-3, B-2, C-1, D-4
2. A-3, B-1, C-4, D-2
3. A-2, B-1, C-4, D-3
4. A-1, B-3, C-4, D-2

Answer: b. A-3, B-1, C-4, D-2

Discussion:

12. Which of the following represents the correct sequence of the origin and conduction of action potential?

1. Bundle of His ► Purkinje fibres ► SA node ► AV node
2. AV node ► SA node ► Bundle of His ► Purkinje fibres
3. SA node ► AV node ► Purkinje fibres ► Bundle of His
4. SA node ► AV node ► Bundle of His ► Purkinje fibres

Answer: d. SA node ► AV node ► Bundle of His ► Purkinje fibres

Discussion: The correct sequence of the origin and conduction of action potential is SA node ► AV node ► Bundle of His ► Purkinje fibres.

• The sinoatrial node generates the cardiac impulse. It is located in the right atrium.
• The atrioventricular node is in between the right atrium and the right ventricle.
• The bundle of His is situated in the interventricular septa.
• The bundle of His divides into 2 branches and gives rise to fine fibres called Purkinje fibres.

13. Artificial pacemaker is used to replace

1. AVN
2. Purkinje fibres
3. SAN
4. Bundle of His

Answer: c. SAN

Discussion: SA node (SAN) is the pacemaker of the heart. It generates the action potential required for the atria to contract. It is found in the wall of the right atrium near the opening of the superior vena cava.

Sometimes the SAN might get damaged or become defective. This can cause the heart to function improperly. In such a case, the surgical grafting of an artificial pacemaker in the chest of the ailing patient helps to restore and maintain the normal heartbeat.

14. Which of the following events does not take place during the ventricular systole?

1. Due to the ventricular systole, ventricular pressure decreases
2. During the end of ventricular systole, the semilunar valves open up
3. During the start of the ventricular systole, the bicuspid and tricuspid valves close
4. Due to the closure of the atrioventricular valves, dub sound is produced
5. Event 1 and 2 do not take place
6. Event 2 and 3 do not take place
7. Event 1 and 4 do not take place
8. All events take place

Answer: c. Event 1 and 4 do not take place

Discussion: The pressure inside the ventricles increases during ventricular systole. This results in the closure of the bicuspid and tricuspid valve. The closure of these atrioventricular valves produces the lub sound. As the pressure inside the ventricles increases, the semilunar valves open up. Consequently, blood is released into the systemic circulatory system.

After this stage, the pressure inside the ventricles falls and the ventricles relax. The semilunar valve closes during the end of the ventricular diastole. The closing of the semilunar valves produces the dub sound.

15. Match the following

1. A-1, B-2, C-3
2. A-3, B-1, C-2
3. A-2, B-3, C-1
4. A-3, B-2, C-1

Answer: d. A-3, B-2, C-1

Discussion: P wave in the ECG represents the electrical excitation of the atria (depolarisation) which causes contraction of both the atria. The QRS wave represents the depolarisation of the ventricles, which causes ventricular contraction. This contraction starts shortly after the Q wave and marks the beginning of the ventricular systole (a period of contraction of the ventricles). The T wave represents the return of ventricles from an excited state to a normal state (repolarisation). The end of the T wave marks the end of the systole.

Also Check:What does the QRS complex represent in ECG?

16. Red blood cells that do not contain A antigen but have Rh antigen on their surfaces are normally found in the person with blood type

1. A negative or B positive
2. B positive or O positive
3. O negative or B positive
4. AB positive or A positive

Answer: b. B positive or O positive

Discussion: ABO blood grouping is based on the presence or absence of two surface antigens A and B (glycoproteins that can induce an immune response). In addition to the ABO blood grouping system, the other prominent one is the Rh blood group system. If the Rh factor is present, an individual is ‘Rhesus positive’ (Rh +ve). If an Rh factor is absent, the individual is ‘Rhesus negative’ (Rh -ve).

Red blood cells that do not contain A antigens but have Rh antigens on their surfaces may or may not have B antigens. Hence, the blood type can be either B positive or O positive.

17. ⸻ blood group individuals are called universal donors

1. O
2. AB
3. A
4. B

Answer: a. O

Discussion: People with type O -ve blood are called universal donors because their red blood cells have no A, B or Rh antigens and can therefore be safely given to people of any blood group. As the O blood group has no antigen, it will not form agglutination with antibodies of other blood groups.

18. Calculate the cardiac output (ml) of an athlete if the volume of blood pumped by each ventricle per beat is 70 ml and the heart rate is 80 beats per minute.

1. 5040
2. 5400
3. 5600
4. 5800

Answer: c. 5600

Discussion: Stroke volume is the volume of blood that is ejected from each ventricle due to the contraction of the ventricles. Here, the given stroke volume is 70 ml and the heart rate (number of times the heart beats in one minute) is 80.

Cardiac output = Heart rate ✕ Stroke volume

80 ✕ 70

5600 ml

19. The normal blood pressure is ⸻, the condition when the blood pressure exceeds the normal is called as ⸻.

1. 120/80 mmHg, hypotension
2. 80/120 mmHg, blood tension
3. 120/80 mmHg, high blood pressure
4. 120/80 mmHg, hypertension

Answer: d. 120/80 mmHg, hypertension

Discussion: A sphygmomanometer is a device used to measure blood pressure. The normal blood pressure level is 120 mmHg/80 mmHg.

• 120 mmHg – It is the systolic or pumping pressure.
• 80 mmHg – It is the diastolic or resting pressure.

If the blood pressure of an individual is more than 120/80 or higher, it means the person has a condition called hypertension or high blood pressure. Prolonged high blood pressure leads to heart diseases.

20. Deposition of plaque in the blood vessels causes atherosclerosis. The plaque is due to the deposition of

1. Calcium
2. Fat
3. Fibrous tissue
4. All of the above

Answer: d. All of the above

Discussion: The blockage or narrowing of coronary arteries is called coronary artery disease or atherosclerosis. It affects the vessels that supply blood to the heart muscle. It is caused by the build-up of plaque, which is due to the deposition of

• Calcium
• Fat
• Fibrous tissue

This makes the lumen of arteries narrower and affects the supply of blood to heart muscles.

Explore the next chapter’s important questions with regards to NEET, only at BYJU’S. Do check here for the important notes on Body Fluids and Circulation.

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