NCERT Solutions for Class 11 Biology Chapter 18

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

Ans: Components of the formed elements present in the blood are:  

• Erythrocytes: They play a significant role in the transportation of respiratory gasses. 

• Leucocytes: They help to fight against infections and are responsible for the immune system in the body.  

• Platelets: They help in the coagulation of blood. 

2. What is the importance of plasma proteins? 

Ans: Plasma is made up of proteins such as fibrinogens, globulins, and albumins. Fibrinogen plays a very important role in blood clotting. Globulin is an important plasma protein that protects the body from infectious agents. Albumin helps in maintaining osmotic balance.

3. Match column I with column II:  

Ans: 

4. Why do we consider blood as a connective tissue?  

Ans: As the different connective tissues, blood is also mesodermally derived and has an extracellular matrix known as plasma. It connects different body systems and takes part in the transportation of gas and varied nutrients within the body and the removal of the waste materials out of the body.  Hence, blood is taken into account as a connective tissue. 

5. What is the difference between lymph and blood? 

Ans: Differences between lymph and blood are:  

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

Ans: Double circulation- It is defined as the process in which blood passes 2 times through the heart during one complete cycle. This process involves two types of blood circulations:  

• Systemic circulation: In this method, the circulation of oxygenated blood takes place from the left ventricle of the heart to the aorta. Then a network of arteries, arterioles, and capillaries supplies this oxygenated blood to various tissues in the body. From tissues, the deoxygenated blood is collected by a system of venules, veins, and vena cava, and is emptied into the right atrium.

• Pulmonary circulation: Thi circulation involves the circulation of deoxygenated blood from the right ventricle to the pulmonary artery, which then carries blood to the lungs for getting oxygenated.  Then, the oxygenated blood from the lungs is carried by the pulmonary veins into the left atrium.  

Significance of double circulation: In double circulation,  complete separation of oxygenated and deoxygenated blood takes place which allows a more efficient supply of oxygen to the body cells. 

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 

Ans: 

(a) Differences between lymph and blood are:

b) Differences between the open and closed systems of circulation are:

c) Differences between Systole and Diastole are:

d) Difference between P-wave and T- wave

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

Ans: A comparative study of the structures of hearts of vertebrates reveals that there is an evolutionary change in the pattern of heart among the vertebrates. All of the vertebrates possess a  muscular chambered heart. The fishes have a 2-chambered heart; with an atrium and a ventricle,  which then evolved into the three-chambered heart in amphibians and reptiles which have two atria and one ventricle. In this type of heart, both the pureblood and impure blood get mixed in the ventricle. In cases of higher animals like aves, reptiles, and mammals, the heart further evolved out as a well-developed, 4-chambered structure with two atrium and two ventricles. All these groups of animals exhibit double circulation and hence there is no mixing of oxygenated and deoxygenated blood. 

9.  Why do we call our heart myogenic? 

Ans: The normal activities of our heart are autoregulated by specialized muscles known as nodal tissues. Due to this, the heart is known as myogenic. 

10. The sino-atrial node is called the pacemaker of our heart. Why?  

Ans: The sino-atrial (SA) node is a specialized bundle of neurons that have the ability to generate action potential without any external stimuli. This action potential is responsible for initiating and maintaining the rhythmic contraction of the heart. Due to this ability, the SA Node is called the pacemaker.

11. What is the significance of atrioventricular nodes and atrioventricular bundles in the functioning of the heart?  

Ans: Both the atrioventricular node (AVN) and the atrioventricular (AV) bundle are stimulated by the action potential triggered by the sinus node (SAN) and transmit the stimulus to the remaining parts of the heart, thereby helping to transmit the heartbeat to different parts of the heart. 

12. Define a cardiac cycle and the cardiac output.  

Ans: Cardiac cycle: The successive contraction and expansion of different heart chambers in a cyclical manner is called the cardiac cycle. 

Cardiac Output: The volume of blood that the heart pumps in one minute is called the cardiac output. The average cardiac output of a healthy man is 5 liters per minute.

13.  Explain heart sounds. 

Ans: The sounds that are made when the heart valves close and open are called heart sounds. A normal heart makes two distinctive sounds during each cardiac cycle, the first sound is called lub and the second sound is called dub. 

• Lub: This sound is produced by the closing of the tricuspid and bicuspid valves at the beginning of the systole. 

• Dub: This sound is produced by the closing of the half-moon keys at the beginning of the diastole.

14. Draw a standard ECG and explain the different segments in it.  

Ans: The electrocardiogram (ECG) is the graphical representation of the cardiac cycle generated by the electrogram. Below is a schematic of a standard EKG. Each ECG peak, represented by the letters P to T, corresponds to a certain electrical activity of the heart. 

• The first "P" peak indicates atrial depolarization (atrial contraction). 

• The following QRS complex represents the depolarization of the ventricles (ventricular contraction). 

• The final T wave represents ventricular repolarization (ventricular relaxation).

NCERT Solutions for Class 11 Biology Body Fluids and Circulation - Free PDF Download

Body Fluids and Circulation Class 11 NCERT Solutions aim towards helping students grasp the basic understanding of the concepts included in the chapter towards the betterment of performance in the final CBSE Board exams as well as entrance exams for medical colleges like NEET ( AIPMT), and other engineering and medical entrance examinations. These solutions are maintained in regulation with the latest versions of the CBSE guidelines and the Body Fluids and Circulation Class 11 NCERT textbook. The solutions come along with the NCERT Biology Class 11 Body Fluids and Circulations PDF and provide an answer to every question contained in the textbook.

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

Body Fluids and Circulation Class 11 NCERT is part of Unit 5 of the textbook comprising Human Physiology. This particular chapter will help students in understanding the process of blood circulation along with the characteristics of tissue fluids (blood and lymph). Other chief topics and concepts that are discussed in the chapter consist of double circulation, Cardiac process regulation, pathways relating to circulation, disorders concerning cardiac activity, plasma, the whole of the human circulatory system, blood groups, ECG, etc. 

CH 18 Bio Class 11 will familiarize you with the different types of organisms having separated circulatory structures depending upon the level of physical and mental complexity of the animal. It will also attempt to explain the health of the heart, blood transfusions, numerous blood particles along with healthy and unhealthy habits that are likely to affect the health of your heart.

Some of the most common and significant notes on the chapter relate to Cardiac output and ECG which are generally asked in exams.

Chapter 18 Biology Class 11 NCERT Solutions sufficiently emphasize on all of the aforementioned topics through simple diagrams, charts and easily comprehensible content. A student should thoroughly focus on the NCERT textbook and solutions to increase their understanding and assess situations with maximized potential.

NCERT Solutions for Class 11 Chapter 18 - Weightage Marks

Chapter 18 Bio Class 11 belongs to the Unit 5 of the NCERT textbook for Class 11 Biology which generally comes for 18 Marks in the final CBSE Board exam with special emphasis on this chapter. This particular unit is also fairly important while preparing for the NEET examination with the inclusion of 20% of the total grade. Therefore, it is required for students to fully understand the connotation of this chapter so that they can answer different types of questions wisely.

Following are the Main Topics that are Covered Under this Chapter:

• Blood

• Plasma 

• Blood Groups

• Element formation

• Blood Coagulation

• Tissue fluids

• Circulatory System in humans

• The cardiac cycle

• Electrocardiograph

• Double circulation

• Disorders concerning circulation 

• Cardiac activity and its regulation

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

It is extremely necessary for students to maintain an understanding of multiple topics after choosing certain subjects in Class 11th towards potential career interests but firstly for securing good marks in their exams. Following are some of the beneficial characteristics of the CBSE Class 11 Biology Chapter 18 NCERT Solutions in favor of achieving the aforementioned:

• NCERT Solutions for Class 11 Biology Chapter 18 Body Fluids and Circulation provide a thorough explanation of main topics and concepts.

• The language used for these solutions is very simple and can be easily understood by all.

• NCERT Solutions for Class 11 Body Fluids and Circulation assist students in completing one of their chief objectives concerning exams.

• These solutions have been designed by experts and professionals in the subject of biology to provide accuracy with no space for uncertainty.