NCERT Solutions for Class 11 Biology Chapter 18 : Body Fluids and Circulation

Q: Q1. What concepts can I learn from Body Fluids and Circulation NCERT Solutions for Class 11 Biology?

Answer: 18.1 – Blood 18.2 – Lymph (Tissue Fluid) 18.3 – Circulatory Pathways 18.4 – Double Circulation 18.5 – Regulation of Cardiac Activity 18.6 – Disorders of Circulatory System

Q: Q2. What are the advantages of Toppr NCERT Solutions for Class 11 Biology Chapter 18 Body Fluids and Circulation

Answer: Referring to NCERT Solutions for CBSE Class 11 Biology Chapter 18 Body Fluids and Circulation is beneficial during exam preparations. These well-prepared solutions allow students to have a better understanding of the chapter. By downloading Toppr NCERT Solutions for Class 11 Biology Chapter 18, students can find the explanation to the exercise questions asked in the exam. The material is prepared by subject matter experts to help students understand how to write answers in the exam.

Question 1

Name the components of the formed elements in the blood and mention one major function of each of them ?

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Blood is a fluid connective tissue.It is composed of plasma(55%) and formed elements/blood corpuscles(45%).

There are three types of formed elements(blood corpuscles):

1) Erythrocytes (red cells)

2) Leukocytes (white cells)

3) Platelets (thrombocytes)

Erythrocytes (RBC) - Most abundant type of blood cells. Their main function is transport of respiratory gases,mainly oxygen, but they also carry some carbon dioxide.

They also maintain the viscosity and pH of blood.

Leukocytes (WBC) - These cells have an important function in defence and immunity. They detect foreign or abnormal (antigenic) material and destroy it, through a range of defence mechanisms.

There are two main types:

Granulocytes (polymorphonuclear leukocytes)- neutrophils, eosinophils and basophils

Agranulocytes - monocytes and lymphocytes

Platelets (Thrombocytes) - These are very small discs, 2-4 micrometer in diameter. They are responsible for coagulation or clotting of blood.

Answer

Blood is a fluid connective tissue.It is composed of plasma(55%) and formed elements/blood corpuscles(45%).

There are three types of formed elements(blood corpuscles):

1) Erythrocytes (red cells)

2) Leukocytes (white cells)

3) Platelets (thrombocytes)

Erythrocytes (RBC) - Most abundant type of blood cells. Their main function is transport of respiratory gases,mainly oxygen, but they also carry some carbon dioxide.

They also maintain the viscosity and pH of blood.

Leukocytes (WBC) - These cells have an important function in defence and immunity. They detect foreign or abnormal (antigenic) material and destroy it, through a range of defence mechanisms.

There are two main types:

Granulocytes (polymorphonuclear leukocytes)- neutrophils, eosinophils and basophils

Agranulocytes - monocytes and lymphocytes

Platelets (Thrombocytes) - These are very small discs, 2-4 micrometer in diameter. They are responsible for coagulation or clotting of blood.

Question 2

What is the importance of plasma proteins?

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Plasma is the colourless fluid of blood which helps in the transport of food, CO

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, waste products, and salts. It constitutes about 55% of blood. About 6.8% of the plasma is constituted by proteins such as fibrinogens, globulins, and albumins.

Fibrinogen is a plasma glycoprotein synthesised by the liver. It plays a role in the clotting of blood.

Globulin is a major protein of the plasma. It protects the body against infecting agents.

Albumin is a major protein of the plasma. It helps in maintaining the fluid volume within the vascular space.

Answer

Plasma is the colourless fluid of blood which helps in the transport of food, CO

_{2}

, waste products, and salts. It constitutes about 55% of blood. About 6.8% of the plasma is constituted by proteins such as fibrinogens, globulins, and albumins.

Fibrinogen is a plasma glycoprotein synthesised by the liver. It plays a role in the clotting of blood.

Globulin is a major protein of the plasma. It protects the body against infecting agents.

Albumin is a major protein of the plasma. It helps in maintaining the fluid volume within the vascular space.

Question 3

Match the column :

List 1EosinophilsRBCAB GroupPlateletsSystole

List 2CoagulationUniversal RecipientResist infectionsContraction of heartGas transport

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Eosinophils are type of white blood cells which fight (resist) infections.

RBC is a component of blood that works to transport gases (oxygen & carbon dioxide) in the body.

The blood groups are mainly of four types, namely, A, B, AB, and O. In all of these AB is the Universal recipient and O is the universal donor.

Platelets are part of the blood that helps in coagulation (blood clotting).

Systole: It is the time period when the heart contracts.

Answer

Eosinophils are type of white blood cells which fight (resist) infections.

RBC is a component of blood that works to transport gases (oxygen & carbon dioxide) in the body.

The blood groups are mainly of four types, namely, A, B, AB, and O. In all of these AB is the Universal recipient and O is the universal donor.

Platelets are part of the blood that helps in coagulation (blood clotting).

Systole: It is the time period when the heart contracts.

Question 4

Why do we consider blood as a connective tissue?

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Connective tissues have cells scattered throughout an extracellular matrix. They connect different body systems. Blood is considered as a type of connective tissue because it connects the body systems, transports oxygen and nutrients to all the parts of the body, and removes the waste products. Blood has an extra-cellular matrix called plasma, with red blood cells, white blood cells, and platelets floating in it.

Answer

Connective tissues have cells scattered throughout an extracellular matrix. They connect different body systems. Blood is considered as a type of connective tissue because it connects the body systems, transports oxygen and nutrients to all the parts of the body, and removes the waste products. Blood has an extra-cellular matrix called plasma, with red blood cells, white blood cells, and platelets floating in it.

Question 5

What is the difference between blood and lymph?

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BLOOD	LYMPH
1. It is the red-colored fluid connective tissue that contains RBCs.	1. It is a colorless fluid connective tissue in which RBCs are absent.
2. It is associated with the circulation of oxygen and carbon dioxide.	2. It helps in body defence and is a part of immune system.
3. It contains plasma, RBCs, WBCs, platelets, and proteins.	3. It contains plasma, fewer WBCs, and platelets. It lacks proteins.

Answer

BLOOD	LYMPH
1. It is the red-colored fluid connective tissue that contains RBCs.	1. It is a colorless fluid connective tissue in which RBCs are absent.
2. It is associated with the circulation of oxygen and carbon dioxide.	2. It helps in body defence and is a part of immune system.
3. It contains plasma, RBCs, WBCs, platelets, and proteins.	3. It contains plasma, fewer WBCs, and platelets. It lacks proteins.

Question 6

What is meant by double circulation? What is its significance?

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Double circulation is a process during which blood passes twice through the heart during one complete cycle. This type of circulation is found in amphibians, reptiles, birds, and mammals. However, it is more prominent in birds and mammals as in them the heart is completely divided into four chambers – the right atrium, the right ventricle, the left atrium, and the left ventricle.

The movement of blood in an organism is divided into two parts:

(i) Systemic circulation

(ii) Pulmonary circulation

Systemic circulation involves the movement of oxygenated blood from the left ventricle of the heart to the aorta. It is then carried by blood through a network of arteries, arterioles, and capillaries to the tissues. From the tissues, the deoxygenated blood is collected by the venules, veins, and vena cava, and is emptied into the left auricle.
Pulmonary circulation involves the movement of deoxygenated blood from the right ventricle to the pulmonary artery, which then carries blood to the lungs for oxygenation. From the lungs, the oxygenated blood is carried by the pulmonary veins into the left atrium.

Hence, in double circulation, blood has to pass alternately through the lungs and the tissues.

Significance of double circulation:

The separation of oxygenated and deoxygenated blood allows a more efficient supply of oxygen to the body cells. Blood is circulated to the body tissues through systemic circulation and to the lungs through the pulmonary circulation.

Answer

Double circulation is a process during which blood passes twice through the heart during one complete cycle. This type of circulation is found in amphibians, reptiles, birds, and mammals. However, it is more prominent in birds and mammals as in them the heart is completely divided into four chambers – the right atrium, the right ventricle, the left atrium, and the left ventricle.

The movement of blood in an organism is divided into two parts:

(i) Systemic circulation

(ii) Pulmonary circulation

Systemic circulation involves the movement of oxygenated blood from the left ventricle of the heart to the aorta. It is then carried by blood through a network of arteries, arterioles, and capillaries to the tissues. From the tissues, the deoxygenated blood is collected by the venules, veins, and vena cava, and is emptied into the left auricle.
Pulmonary circulation involves the movement of deoxygenated blood from the right ventricle to the pulmonary artery, which then carries blood to the lungs for oxygenation. From the lungs, the oxygenated blood is carried by the pulmonary veins into the left atrium.

Hence, in double circulation, blood has to pass alternately through the lungs and the tissues.

Significance of double circulation:

The separation of oxygenated and deoxygenated blood allows a more efficient supply of oxygen to the body cells. Blood is circulated to the body tissues through systemic circulation and to the lungs through the pulmonary circulation.

Question 7

Write the differences between.

(a) Blood and Lymph

(b) Open and closed system of circulation

(c) Systole and diastole

(d) P- wave and T- wave

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(a) Blood and Lymph

Lymph	Blood
It is a colourless fluid.	It is red-coloured fluid.
It contains plasma and lesser number of WBCs and platelets.	It contains plasma, RBCs, WBCs, and platelets.
It transports nutrients from the tissue cells to the blood, through lymphatic vessels.	It transports nutrients and oxygen from one organ to another.
It helps in body defence and is a part of the immune system.	It helps in the circulation of oxygen and carbon dioxide.

(b) Open and Closed system of circulation

Open system of circulation	Closed system of circulation
In this system, blood is pumped by the heart, through large vessels, into body cavities called sinuses.	In this system, blood is pumped by the heart, through a closed network of vessels.
The body tissues are in direct contact with blood.	The body tissues are in indirect contact with blood.
Blood flows at low pressure.	Blood flows at high pressure.
Blood flow cannot be regulated.	Blood flow can be regulated
This is present in arthropods and molluscs.	This is present in annelids, echinoderms, and vertebrates.

(c) Systole and Diastole

Systole	Diastole
It is the contraction of the heart chambers to drive blood into the aorta and the pulmonary artery.	It is the relaxation of the heart chambers between two contractions.
Systole decreases the volume of the heart chambers and forces the blood out of them.	Diastole brings the heart chambers back into their original sizes to receive more blood

(d) P-wave and T-wave

P-wave	T-wave
In an electrocardiogram (ECG), the P-wave indicates the activation of the Sino-atrial node.	In an electrocardiogram (ECG), the T-wave represents ventricular relaxation.
During this phase, the impulse of contraction is generated by the SA node, causing atrial depolarisation.	During this phase, the ventricles relax and return to their normal state.
It is of atrial origin.	It is of ventricular origin.

Answer

(a) Blood and Lymph

Lymph	Blood
It is a colourless fluid.	It is red-coloured fluid.
It contains plasma and lesser number of WBCs and platelets.	It contains plasma, RBCs, WBCs, and platelets.
It transports nutrients from the tissue cells to the blood, through lymphatic vessels.	It transports nutrients and oxygen from one organ to another.
It helps in body defence and is a part of the immune system.	It helps in the circulation of oxygen and carbon dioxide.

(b) Open and Closed system of circulation

Open system of circulation	Closed system of circulation
In this system, blood is pumped by the heart, through large vessels, into body cavities called sinuses.	In this system, blood is pumped by the heart, through a closed network of vessels.
The body tissues are in direct contact with blood.	The body tissues are in indirect contact with blood.
Blood flows at low pressure.	Blood flows at high pressure.
Blood flow cannot be regulated.	Blood flow can be regulated
This is present in arthropods and molluscs.	This is present in annelids, echinoderms, and vertebrates.

(c) Systole and Diastole

Systole	Diastole
It is the contraction of the heart chambers to drive blood into the aorta and the pulmonary artery.	It is the relaxation of the heart chambers between two contractions.
Systole decreases the volume of the heart chambers and forces the blood out of them.	Diastole brings the heart chambers back into their original sizes to receive more blood

(d) P-wave and T-wave

P-wave	T-wave
In an electrocardiogram (ECG), the P-wave indicates the activation of the Sino-atrial node.	In an electrocardiogram (ECG), the T-wave represents ventricular relaxation.
During this phase, the impulse of contraction is generated by the SA node, causing atrial depolarisation.	During this phase, the ventricles relax and return to their normal state.
It is of atrial origin.	It is of ventricular origin.

Question 8

Describe the evolutionary change in the pattern of heart among the vertebrates.

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Heart is a hollow muscular organ present in all vertebrates which pump blood to whole of the body. Evolutionary change in the heart is observed on the basis of separation of oxygenated and deoxygenated blood for efficient oxygen transport to the body.

Fish heart- It is made up of 2 chambers- one auricle and one ventricle. Since there is no division of auricles and ventricles, deoxygenated blood passes through it which enters the gills for oxygenation. It has two additional chambers such as sinus venosus and conus arteriosus.

Amphibian heart- It has 3 chambers- 2 auricles and one ventricle. The auricles are divided by a septum while ventricle is undivided. Additional chambers such as sinus venosus and conus arteriosus are also present. The deoxygenated blood from whole body enters the right auricle while oxygenated blood enters the left auricle from the lungs and ultimately two types of blood get mixed up in ventricle.

Reptilian heart- It is incompletely 4 chambered except in crocodiles, alligators and gharials. They have only one accessory chamber called sinus venosus. The reptilian heart also shows mixed blood circulation.

Avian and mammalian hearts- It is made up of four chambers- 2 auricles and two ventricles. These two pairs of chambers separate oxygenated and deoxygenated blood. The upper two chambers are called atria and the lower two chambers are called ventricles. The chambers are separated by a muscular wall that prevents the mixing of the blood rich in oxygen with the blood rich in carbon dioxide.

Answer

Heart is a hollow muscular organ present in all vertebrates which pump blood to whole of the body. Evolutionary change in the heart is observed on the basis of separation of oxygenated and deoxygenated blood for efficient oxygen transport to the body.

Fish heart- It is made up of 2 chambers- one auricle and one ventricle. Since there is no division of auricles and ventricles, deoxygenated blood passes through it which enters the gills for oxygenation. It has two additional chambers such as sinus venosus and conus arteriosus.

Amphibian heart- It has 3 chambers- 2 auricles and one ventricle. The auricles are divided by a septum while ventricle is undivided. Additional chambers such as sinus venosus and conus arteriosus are also present. The deoxygenated blood from whole body enters the right auricle while oxygenated blood enters the left auricle from the lungs and ultimately two types of blood get mixed up in ventricle.

Reptilian heart- It is incompletely 4 chambered except in crocodiles, alligators and gharials. They have only one accessory chamber called sinus venosus. The reptilian heart also shows mixed blood circulation.

Avian and mammalian hearts- It is made up of four chambers- 2 auricles and two ventricles. These two pairs of chambers separate oxygenated and deoxygenated blood. The upper two chambers are called atria and the lower two chambers are called ventricles. The chambers are separated by a muscular wall that prevents the mixing of the blood rich in oxygen with the blood rich in carbon dioxide.

Question 9

Why do we call our heart myogenic?

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In the human heart, contraction is initiated by a specially modified heart muscle known as the sinoatrial node. It is located in the right atrium. The SA node has the inherent power of generating a wave of contraction and controlling the heartbeat.
Hence, it is known as the pacemaker. Since the heartbeat is initiated by the SA node and the impulse of contraction originates in the heart itself, the human heart is termed as myogenic. The hearts of vertebrates and mollusks are also myogenic.

Answer

In the human heart, contraction is initiated by a specially modified heart muscle known as the sinoatrial node. It is located in the right atrium. The SA node has the inherent power of generating a wave of contraction and controlling the heartbeat.
Hence, it is known as the pacemaker. Since the heartbeat is initiated by the SA node and the impulse of contraction originates in the heart itself, the human heart is termed as myogenic. The hearts of vertebrates and mollusks are also myogenic.

Question 10

Sino-atrial node is called as the pacemaker of our heart. Why?

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The sino-atrial (SA) node is a specialised bundle of neurons located in the upper part of the right atrium of the heart. The cardiac impulse originating from the SA node triggers a sequence of electrical events in the heart, thereby controlling the sequence of muscle contraction that pumps blood out of the heart. Since the SA node initiates and maintains the rhythmicity of the heart, it is known as the natural pacemaker of the human body.

Answer

The sino-atrial (SA) node is a specialised bundle of neurons located in the upper part of the right atrium of the heart. The cardiac impulse originating from the SA node triggers a sequence of electrical events in the heart, thereby controlling the sequence of muscle contraction that pumps blood out of the heart. Since the SA node initiates and maintains the rhythmicity of the heart, it is known as the natural pacemaker of the human body.

NCERT Solutions for Class 11 Biology Chapter 18 : Body Fluids and Circulation

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