NCERT Exemplar Class 11 Biology Solutions Chapter 18 Body Fluids and Circulation

Which of the following cells does not exhibit phagocytic activity?
(a) Monocytes
(b) Neutrophil
(c) Basophil
(d) Macrophage

Answer:

The answer is option (c) Basophil
Explanation: Basophils are involved in inflammatory reactions and the secretion of histamine, serotonin,
etc. It does not exhibit phagocytic activity.

Question:2

One of the common symptoms observed in people infected with Dengue fever is
(a) Significant decrease in RBC count
(b) Significant decrease in WBC count
(c) Significant decrease in platelets count
(d) Significant increase in platelets count

Answer:

The answer is the option (c) Significant decrease in platelets count
Explanation: Low platelet count is one of the ways to diagnose Dengue Fever. It attacks the platelets in our body, reducing them.

Question:3

Which among the followings is correct during each cardiac cycle?
(a) The volume of blood pumped out by the Rt and Lt ventricles is same.
(b) The volume of blood pumped out by the Rt, and Lt ventricle is different
(c) The volume of blood received by each atrium is different
(d) The volume of blood received by the aorta and pulmonary artery is different

Answer:

The answer is the option (a) The volume of blood pumped out by the Rt and Lt ventricles is same.

Explanation: After oxygenation, the volume of the blood entering the lung is the same as the volume of blood leaving it. In the case of varying volume, the heart is susceptible to heart failure due to different pressure.

Question:4

Cardiac activity could be moderated by the autonomous neural system.

Tick the correct answer:

(a) The parasympathetic system stimulates the heart rate and stroke volume
(b) The sympathetic system stimulates the heart rate and stroke volume
(c) The parasympathetic system decreases the heart rate but increases stroke volume
(d) The sympathetic system decreases the heart rate but increases stroke volume

Answer:

The answer is the option (b) The sympathetic system stimulates the heart rate and stroke volume

Explanation: Neural signals from the sympathetic nerves can increase the rate of heartbeat, the strength of the ventricular contraction in the heart, thereby stimulating heart rate and stroke volume.

Question:5

Mark the pair of substances among the following which is essential for coagulation of blood.
(a) Heparin and calcium ions
(b) Calcium ions and platelet factors
(c) Oxalates and citrates
(d) Platelet factors and heparin

Answer:

The answer is the option (b) calcium ions and platelets factors
Explanation- calcium ions and platelets facilitate the conversion of fibrinogen into fibrin so that the blood can coagulate.

Question:6

ECG depicts the depolarisation and repolarisation processes during the cardiac cycle. In the ECG of a normal healthy individual one of the following waves is not represented.

(a) Depolarisation of atria
(b) Repolarisation of atria
(c) Depolarisation of ventricles
(d) Repolarisation of ventricles

Answer:

The answer is the option (b) Repolarisation of atria

Explanation: In a normal ECG, P-wave depolarization of atria, QRS complex-ventricular depolarization, T-wave repolarization of ventricles are depicted. Therefore, the repolarization of atria is not shown.

Question:7

Which one of the following types of cells lack nucleus in humans?
(a) RBC
(b) Neutrophils
(c) Eosinophils
(d) Erythrocytes

Answer:

The answer is option (a) RBC

Explanation- RBCs are the only mammalian cells that do not contain nucleus and mitochondria.

Question:8

Which one of the following blood cells is involved in antibody production?
(a) B-Lymphocytes
(b) T-Lymphocytes
(e) RBC
(d) Neutrophils

Answer:

The answer is option (a) B-Lymphocytes
Explanation- The primary function of B-Lymphocytes is to create antibodies against soluble antigens in the human body.

Question:9

The cardiac impulse is initiated and conducted further up to ventricle. The correct sequence of conduction of impulse is

Answer:

The answer is option (c)

Explanation: The contraction starts in the SA Node; the wave of contraction reaches the AV Node then via the AV Bundle the impulse of contraction is spread, and finally, the Purkinje Fiber stimulates the heartbeat.

Question:10

Agranulocytes responsible for the immune response of the body are
(a) Basophils
(b) Neutrophils
(c) Eosinophils
(d) Lymphocytes

Answer:

The answer is the option (d) Lymphocytes
Explanation- Lymphocytes are responsible for producing antibodies and immune response.

Question:11

The second heart sound (dubb) is associated with the closure of
(a) Tricuspid valve
(b) Semilunar valves
(c) Bicuspid valve
(d) Tricuspid and bicuspid valves.

Answer:

The answer is the option (b) Semilunar valve
Explanation: The bicuspid valve, tricuspid valve and both together are associated with the first heart sound, and the semilunar valve is associated with the second.

Question:12

Which of the following correctly explains a phase/ event in the cardiac cycle in a standard electrocardiogram?
(a) QRS complex indicates atrial contraction.
(b) QRS complex indicates ventricular contraction.
(c) The time between S and T represents atrial systole.
(d) P-wave indicates the beginning of ventricular contraction.

Answer:

The answer is option (b) QRS complex indicates ventricular contraction
Explanation: The QRS wave starts with a downward deflection and continues as an upright triangular wave with downward waves as its base. It indicates ventricular depolarization or contraction.

Question:13

Which of the following statements is incorrect?
(a) A person of ‘O’ blood group has anti ‘A’ and anti ‘B’ antibodies in his blood plasma.
(b) A person of ‘B’ blood group can’t donate blood to a person of ‘A’ blood group.
(c) Blood group is designated based on the presence of antibodies in the blood plasma.
(d) A person of AB blood group is a universal recipient.

Answer:

The answer is the option (c) Blood group is designated on the basis of the presence of antibodies in the blood Plasma.

Explanation: Blood group is based on the presence or absence of antigens A and B on RBCs and presence or absence of two natural antibodies present in plasma.

Question:14

What would be the cardiac output of a person having 72 heartbeats per minute and a stroke volume of 50 mL?

(a) 360 mL
(b) 3600 mL
(c) 7200 mL
(d) 5000 mL

Answer:

The answer is option (b), 3600 mL

Explanation:
Cardiac output= Stroke volume X heart rate
=50×72=3600mL

Question:15

Match the terms given under Column ‘A’ with their functions given under Column ‘B’ and select the
answer from the options given below:

Options:
(a) A – (ii), B – (i), C – (iii), D – (iv)
(b) A – (iii), B – (i), C – (iv), D – (ii)
(c) A – (iii), B – (i), C – (ii), D – (iv)
(d) A – (ii), B – (i), C – (iii), D – (iv)

Answer:

The answer is the option (b) A – (iii), B – (i), C – (iv), D – (ii)

Explanation:

Question:16

Read the following statements and choose the correct option

Statement 1: Atria receive blood from all parts of the body, which subsequently flows to ventricles.

Statement 2: Action potential generated at the sino-atrial node passes from atria to ventricles.

a) Action mentioned in Statement 1 is dependent on action mentioned in Statement 2
b) Action mentioned in Statement 2 is dependent on action mentioned in Statement 1
c) Action mentioned in Statements 1 and 2 is independent of each other.
d) Action mentioned in Statements 1 and 2 is synchronous.

Answer:

The answer is the option (d) Action mentioned in Statements 1 and 2 are synchronous.
Explanation:
Right atria receive blood from the superior vena cava and the left atria from the lungs. The blood then flows into the ventricles. The contraction in Atria moves from SA nodes to AV nodes and then the Purkinje Fibers thereby making the two statements synchronous.

Access Answers to NCERT Exemplar Class 11 Science Chapter 18 Body Fluids and Circulation (Very Short Answer)

The detailed answers to the Very Short Answer questions are given below:

Question:1

Name the blood component which is viscous and straw coloured fluid.

Answer:

Plasma.

Question:2

Complete the missing word in the statement given below:

(a) Plasma without __________ factors is called serum.
(b) __________and monocytes are phagocytic cells.
(c) Eosinophils are associated with__________ reactions.
(d) ___________ions play a significant role in clotting.
(e) One can determine the heartbeat rate by counting the number of __________ in an ECG.

Answer:

(a) blood Clotting
(b) Neutrophils
(c) allergic
(d) Calcium
(e) QRS

Question:3

Given below is the diagrammatic representation of a standard ECG. Label its different peaks.

Answer:

Question:4

Name the vascular connection that exists between the digestive tract and liver.

Answer:

Hepatic portal system

Question:5

Given below are the abnormal conditions related to blood circulation. Name the disorders.

(a) Acute chest pain due to failure of O₂ supply to heart muscles
(b) Increased systolic pressure

Answer:

(a) Angina Pectoris
(b) Hypertension or blood pressure

Question:6

Which coronary artery disease is caused due to narrowing of the lumen of arteries?

Answer:

Atherosclerosis

Question:7

Define the following terms and give their location?
(a) Purkinje fibre
(b) Bundle of His

Answer:

(a) The conducting fibres which stimulate impulses are called Purkinje fibres. They are present in the ventricular myocardium.
(b) Bundle of His are special fibres including the Purkinje fibre originating from the AV node. It is found in the well of the right atrium.

Question:8

State the functions of the following in blood
(a) Fibrinogen
(b) Globulin
(c) Neutrophils
(d) Lymphocytes

Answer:

(a) Fibrinogen helps in converting fibrin for blood clotting.
(b) They help in immunity.
(c) They help in destroying foreign materials.
(d) They are responsible for stimulating immune responses.

Question:9

What physiological circumstances lead to erythroblastosis foetalis?

Answer:

Erythroblastosis foetalis is caused by Rh incompatibility or mismatching, which is observed between the Rh-negative blood of a pregnant mother with Rh +ve blood of the fetus. This could cause anaemia or even the death of the fetus. The mother can also be at equal risk.

Question:10

Explain the consequences of a situation in which blood does not coagulate.

Answer:

If blood does not coagulate, it can lead to excessive loss of blood, leading to Hemorrhage.

Question:11

What is the significance of the time gap in the passage of action potential from the sino-atrial node to the ventricle?

Answer:

It allows the relaxation of the ventricles, which leads to a decrease in ventricular pressure causing the semilunar valves to close and hence prevents the blood from backflowing into the ventricles.

Question:12

How will you interpret an electrocardiogram (ECG) in which time taken in QRS complex is higher?

Answer:

If QRS complex is higher, it will be an indication of myocardial infarction or heart attack.

Get Answers to NCERT Exemplar Class 11 Science Chapter 18 Body Fluids and Circulation (Short Answer)

The detailed answers to the Short Answer questions are given below:

Question:1

The walls of ventricles are much thicker than atria. Explain.

Answer:

The walls of ventricles are much thicker as they exert more pressure in the pumping of blood to most of the body parts. The left ventricle has three times thicker walls than the right. The atria is a collecting chamber and is thus thin-walled.

Question:2

Differentiate between
(a) Blood and Lymph
(b) Basophils and Eosinophils
(c) Tricuspid and bicuspid valve

Answer:

(a)

(b)

(c)

Question:3

Briefly describe the followings:
(a) Anaemia
(b) Angina Pectoris
(c) Atherosclerosis
(d) Hypertension
(e) Heart failure
(f) Erythroblastosis foetalis

Answer:

(a) Decrease in the total number of RBCs which is less than normal causes anaemia. Another cause for it is the lesser than normal quantity of haemoglobin.

(b) Pain emerging in the chest region due to insufficient oxygen supply to the hearts is called angina pectoris.

(c) It is a disease in which there is a deposition of plaque due to high cholesterol levels. It blocks the coronary arteries leading to various heart diseases.

(d) It is a disorder in which the blood pressure is higher than normal, which is 120/80.

(e) Heart failures occur when the heart is congested and is unable to pump blood to meet the needs of the body. It is different from a heart attack.

(f) Erythroblastosis foetalis is caused by Rh incompatibility or mismatching, which is observed between the Rh-negative blood of a pregnant mother with Rh +ve blood of the fetus. This could cause anaemia or even the death of the fetus. The mother can also be at equal risk.

Question:4

Explain the advantage of the complete partition of ventricle among birds and mammals and hence leading to double circulation.

Answer:

It results in complete separation of oxygenated and deoxygenated blood, which leads to double circulation (systemic and pulmonary circulation), allowing the more efficient supply of oxygen into the cells and not mixing the two blood.

Question:5

What is the significance of the hepatic portal system in the circulatory system?

Answer:

Significance of the Hepatic Portal System:
(a) Drugs that are metabolized by the liver are enhanced by the hepatic portal system.
(b) It helps in removing harmful materials like ammonia by converting it into urea from the body.
(c) It helps in the transportation of proteins that are produced by the liver

Question:6

Explain the functional significance of the lymphatic system?

Answer:

Significant functions of the lymphatic system:
(a) It helps in collecting the interstitial fluid from tissues.
(b) Lymph nodes produce WBC and antibodies that are essential for immunity of the human body.
(c) It transports many important digested fats, hormones, fat-soluble vitamins etc.
(d) The lymphatic system plays an essential role in the absorption of fat.

Question:7

Write the features that distinguish between the two
(a) Plasma and Serum
(b) Open and closed circulatory system
(c) Sino-atrial node and Atrio-ventricular node

Answer:

Question:8

Thrombocytes are essential for the coagulation of blood. Comment.

Answer:

Thrombocytes or platelets play an essential role in blood coagulation. Thrombocytes forms the bulk of the blood clot. They coalesce together to form the clot. Fibrin develops a mesh around the cluster of platelets. Therefore, along with fibrin, platelets are also essential for blood coagulation.

Question:9

Answer the following
(a) Name the major site where RBCs are formed.
(b) Which part of the heart is responsible for initiating and maintaining its rhythmic activity?
(c) What is specific in the heart of crocodiles among reptilians?

Answer:

(a) In adults- bone marrow and in embryos- liver.

(b) Sino-Atrial Node

(c) Most of the reptiles have three-chambered hearts, but crocodiles have four-chambered hearts

Know Answers to NCERT Exemplar Class 11 Science Chapter 18 Body Fluids and Circulation (Long Answer)

The detailed answers to the Long Answer questions are given below:

Question:1

Explain Rh-incompatibility in humans.

Answer:

Rh grouping of blood is based on the presence and absence of the Rh factor in the blood. If it is present, blood is said to be Rh-positive, if not, it is said to be Rh-negative. If the Rh factor is present, then the blood group is said to be Rh-positive; otherwise, it is called Rh-negative.
Rh incompatibility or mismatching is observed between the Rh-negative blood of a pregnant mother with Rh +ve blood of the fetus. It is known as Erythroblastosis Foetalis. This could cause anaemia or even the death of the fetus. The mother can also be at equal risk.

Question:2

Describe the events in the cardiac cycle. Explain “double circulation”.

Answer:

The cardiac cycle comprises one heartbeat, which can also be understood as the contraction and relaxation of cardiac muscles per cycle. The contraction phase of atria and ventricles is called the systole, and the relaxation is called the diastole. The stages are as follows-

1. Atrial systole: The contraction wave contracts the atria stimulated by the SA node, and the blood is moved into the ventricles as the bicuspids and tricuspids are open.

2. Ventricular systole: The beginning of the ventricular systole is stimulated by the AV node. The bicuspid and tricuspid valves close, making the first heart sound. The complete ventricular contraction occurs, the semilunar valves open, and the blood is forced into the pulmonary trunk and aorta.

3. Beginning of ventricular diastole: The ventricles relax, and as the semilunar valves close, the second heart sound is created.

4. Joint diastole: As the ventricles relax, the tricuspid and bicuspid valves are forced open, and the blood can now move freely to the ventricles.

Double Circulation: In a cardiac cycle, blood flows through the heart twice, and this circulation is called double circulation. It results in complete separation of oxygenated and deoxygenated blood, which leads to the systemic and pulmonary circulation, allowing the more efficient supply of oxygen into the cells and not mixing the two blood.

Question:3

Explain different types of blood groups and donor compatibility by making a table.

Answer:

Question:4

Write a short note on the following
(a) Hypertension
(b) Coronary Artery Disease

Answer:

(a) Hypertension is increased blood pressure. It is a disorder in which the blood pressure is higher than normal, which is 120/80 mm Hg. The first denomination indicates systolic blood pressure and the lower one is diastolic blood pressure. If the blood pressure is more than 140/90 mm Hg or more, then the person is said to have a blood pressure problem or hypertension. It can have adverse effects on the heart, kidneys, liver and even brain.

(b) Atherosclerosis is related to coronary arteries. It reduces the volume of the blood that is supplied to the cardiac muscles. This condition is also known as coronary artery disease (CAD). CAD can lead to heart attacks and even heart failures.

Question:5

In the diagrammatic presentation of heart given below, mark and label, SAN, AVN, AV bundles, bundle of His and Purkinje fibres.

Answer: