The NCERT Solutions for Class 11 Biology Chapter 15 Body Fluids and Circulation explores how blood and lymph function in the body. This chapter also explains the mechanism of blood clotting and the importance of various blood groups, such as A, B, and O. The structure of blood and the anatomy of the heart are described clearly, along with labelled diagrams. The NCERT Solutions provide detailed and easy-to-understand explanations for all the questions.
The Body Fluids and Circulation class 11 question answer describes the heart's structure and function, as well as the concept of double circulation. The regulation of cardiac activity gives students a detailed knowledge of the transportation of nutrients around the body. By studying the Body Fluids and Circulation chapter, they can understand how oxygen and waste are transported in the body. To make learning easier and build a strong foundation, students can make the most of the NCERT Class 11 Solutions.
Class 11 Biology Chapter 15 Body Fluids and Circulation Solutions (Exercise Questions)
The detailed answers to all the questions are given below. Students can use the Class 11 Biology Chapter 15 Body Fluids and Circulation question answer to strengthen their revision and score better in exams. Each solution is explained step by step and follows the NCERT guidelines which makes concepts clear.
Question 1. Name the components of the formed elements in the blood and mention one major function of each of them.
Answer:
The following formed elements were discovered in the blood:
(1) Erythrocytes: The most prevalent type of red blood cells, erythrocytes are coloured red by the red pigment known as haemoglobin. Every part of the body receives oxygen from erythrocytes. Some body parts, like the marrow of long bones, ribs, etc., continuously produce these. Each cubic millimetre of blood contains roughly 4–6 million red blood cells.
(2) Leukocytes: These are colourless cells devoid of haemoglobin. They are the largest cells in blood (larger than RBCs) .
(a) Granulocytes- These leukocytes have granules in their cytoplasm and include neutrophils, eosinophils, and basophils. Neutrophils are phagocytic cells that protect the body against various infecting agents. Eosinophils are associated with allergic reactions, while basophils are involved in inflammatory responses.
(b) Agranulocytes- Lymphocytes and monocytes are agranulocytes. Lymphocytes generate immune responses against infecting agents, while monocytes are phagocytic in nature.
(3) Platelets- These are small irregular bodies present in the blood. They contain essential chemicals that help in clotting. The main function of platelets is to promote clotting.
Question 2. What is the importance of plasma proteins?
Answer:
About 55% of blood is made up of plasma, the colourless fluid. It facilitates the transportation of waste materials, salts, food, and carbon dioxide, among other things. Proteins like albumins, globulins, and fibrinogens make up around 6.8% of plasma. The liver produces the plasma glycoprotein fibrinogen. It contributes to blood coagulation. One of the main proteins in plasma, globulin, shields the body from pathogens. One of the main proteins in plasma that keeps the fluid volume in the vascular space constant is albumin.
Question 3. Match Column I with Column II :
| Column I | Column II |
|---|
| (a) Eosinophils | (i) Coagulation |
| (b) RBC | (ii) Universal Recipient |
| (c) AB Group | (iii) Resist Infections |
| (d) Platelets | (iv) Contraction of the Heart |
| (e) Systole | (v) Gas transport |
Answer:
The correct matching is a-iii, b-v, c-ii, d-i, e-iv
| Column I | Column II |
|---|
| (a) Eosinophils | (iii) Resist Infections |
| (b) RBC | (v) Gas transport |
| (c) AB Group | (ii) Universal Recipient |
| (d) Platelets | (i) Coagulation |
| (e) Systole | (iv) Contraction of Heart |
Question 4. Why do we consider blood as a connective tissue?
Answer:
For the following reasons, we view blood as connective tissue:
- The body's other organs are held together, connected, or supported by connective tissues.
- They are the body's most prevalent and plentiful tissue.
- Gases, nutrients, and hormones are all transported by blood between the body's organs.
- It circulates throughout the body.
- Blood is, therefore, regarded as connective tissue.
Question 5. What is the difference between lymph and blood?
Answer:
Blood
- Blood is a red colour connective tissue.
- It consists of hemoglobin, red blood cells, white blood cells, and platelets. It circulates via arteries, veins, and capillaries.
- Blood transports gases and nutrients to various parts of the body.
Lymph
- Lymph is a white-coloured fluid in the body.
- It has white blood cells known as lymphocytes and flows through vessels called lymph.
- The lymph system facilitates the interchange of gases and nutrients between the body's cells and blood.
Question 6. What is meant by double circulation? What is its significance?
Answer:
Double circulation occurs when blood flows through the heart twice in a single cycle. Although it can be found in birds, mammals, amphibians, and reptiles, it is most noticeable in birds and mammals because of their four-chambered hearts:
- Atrium on the right
- The right ventricle
- Atrium on the left
- The left ventricle
The circulation of blood is separated into:
Systemic circulation: Blood that has been oxygenated leaves the left ventricle and travels to the aorta, then passes through arteries to reach bodily tissues before returning to the right atrium as deoxygenated blood.
Pulmonary circulation: Blood that has lost oxygen travels from the right ventricle to the lungs for oxygenation before returning to the left atrium.
By separating oxygenated and deoxygenated blood, double circulation guarantees an effective oxygen supply.
Question 7. (a) Write the differences between Blood and Lymph
Answer:
Blood | Lymph |
| Red liquid connective tissue that circulates in blood vessels. | White tissue fluid that circulates in lymphatic vessels. |
| Red due to the presence of haemoglobin. | Colourless or pale yellow due to the absence of haemoglobin. |
| Contains red blood cells (RBCs), white blood cells (WBCs), platelets, plasma, and haemoglobin. | Contains white blood cells (mainly lymphocytes), proteins, and plasma but lacks RBCs and platelets. |
| Transports oxygen, nutrients, hormones, and waste products throughout the body. | Helps in immunity, removal of waste, and exchange of nutrients and gases between blood and cells. |
| Travels through arteries, veins, and capillaries. | Travels through lymphatic vessels. |
| Circulated by the heart. | Moves slowly without a central pump, relying on muscle movement and valves. |
Question 7. (b) Write the differences between Open and Closed system of Circulation
Answer:
Open circulatory system:
- The blood vessels open into spaces and not into capillaries.
- Blood comes in direct contact with tissues.
Closed circulatory system:
- Blood flows through capillaries.
- It is connected by arteries and veins.
Question 7. (c) Write the differences between Systole and Diastole
Answer:
Systole:
- It is the heart's chambers contracting.
- It raises the heart's internal blood pressure.
- When the chambers are in systole, blood is pumped out.
Diastole:
- It is the heart's chambers relaxing.
- The heart's blood pressure drops.
- The chambers in diastole receive blood.
Question 7. (d) Write the differences between the P-wave and the T-wave
Answer:
P-Wave:
- P-wave represents the depolarisation or electrical excitation of the atria.
- Blood is pumped into the ventricles.
T-Wave
- The T-wave represents the repolarisation of the ventricles.
- Blood is received by the atria.
Question 8. Describe the evolutionary change in the pattern of heart among the vertebrates.
Answer:
- In vertebrates, the heart has changed from having two chambers in fish to having four chambers in mammals and birds.
- In fish, deoxygenated blood is pumped to the gills for oxygenation by the heart's two chambers.
- Amphibians have three chambers, a ventricle, two atria, and a mixture of oxygenated and deoxygenated blood in the ventricle.
- In reptiles, blood mixing is decreased by an incomplete septum.
- The four-chambered hearts of crocodiles, birds, and mammals guarantee that oxygenated and deoxygenated blood are completely separated.
This development increases the availability of oxygen and effectively controls blood flow.
Question 9. Why do we call our hearts myogenic?
Answer:
Because the cardiac impulse starts in the heart's muscles, the organ is known as myogenic. The heart beats as a result of impulses produced by the SA node, a specialized cardiac tissue, spreading throughout the heart walls.
"Genic" means coming from, and "myo" means muscle.
Question 10. The sino-atrial node is called the pacemaker of the heart. Why?
Answer:
The sino-atrial node is referred to as the heart's pacemaker due to its ability to generate a cardiac impulse. The cardiac impulse and action potential are produced by the sinoatrial node. The atria and ventricles then contract or relax as a result of this cardiac impulse spreading throughout them.
The maximum number of action potentials that the SA node can produce is roughly 70–75 per minute. It also regulates the heart's rhythmic contractions.
Question 12. Define the cardiac cycle and the cardiac output.
Answer:
Cardiac cycle
- The alternating contraction and relaxation of the heart chambers, which is also referred to as diastole and systole, is what causes the blood to circulate in the heart.
- There is a relaxation or expansion phase (diastole) after each contraction phase (systole).
- The cardiac cycle, which lasts 0.8 seconds, is the sequence of events that take place during a single heartbeat.
Cardiac Output
- The cardiac output is the volume of blood pumped by each ventricle in a minute.
Question 13. Explain heart sounds.
Answer:
Every heartbeat is followed by a series of heart sounds.
- Every cardiac cycle produces the sounds "lub" and "dub."
- The first low-pitched sound, "lub," is produced when the tricuspid and bicuspid valves close.
- The second high-pitched sound, "dub," is produced when the semi-lunar valves close.
- For the diagnosis of heart-related conditions, these sounds are important.
Question 14. Draw a standard ECG and explain the different segments in it.
Answer:
The heart's activity during a cardiac cycle is represented graphically by an ECG. Electrocardiograph, or ECG. Assume that a patient has three electrical leads attached to the device—one to the left ankle and one to each wrist—and that the device is continuously monitoring the patient's heart activity. Several leads are connected to the chest area for a thorough assessment of the heart's performance.
Every ECG peak is denoted by a letter, ranging from P to T, which represents a distinct electrical activity of the heart.
The P-wave is a representation of the electrical excitation (or depolarisation) of the atria, which causes both atria to contract.
The QRS complex stands for the ventricles' depolarisation, which starts the ventricular contraction. Shortly after, the contraction begins.
T-wave symbolises the ventricles' repolarisation or transition from an excited to a normal state.
The systole ends when the T-wave ends. Naturally, one can calculate a person's heartbeat rate by counting the number of QRS complexes that occur in a specific amount of time. For a given lead configuration, the ECGs from different people have a similar shape, so any deviation from this shape suggests a potential abnormality or illness. It is, therefore, very important from a clinical standpoint.
NCERT Solutions for Class 11: Subject-wise
Important Question of NCERT Chapter 15 Body Fluids and Circulation
The chapter explores the mechanisms by which substances like oxygen and nutrients are transported, and the function of the Human Circulatory System. Doing practice of the questions given in the NCERT Solutions for Class 11 Biology Chapter 15 Body Fluids and Circulation improves understanding.
Question: Arrange the following blood vessels in descending order of their average pressure.
Aorta, artery, arteriole, capillary, venule, vein.
Choose the correct option:
A. Aorta > arteriole > venule > artery > vein > capillary.
B. Aorta > artery > arteriole > capillary > venule > vein.
C. Capillary > arteriole > venule > artery > vein > aorta.
D. Capillary > vein > venule > arteriole > artery > aorta.
Answer: The correct answer is option (B) Aorta > artery > arteriole > capillary > venule > vein.
Explanation:
In terms of average pressure, the correct arrangement is as follows: Aorta > artery > arteriole > capillary > venule > vein. The aorta, being the largest artery, experiences the highest pressure as it receives blood directly from the left ventricle. The pressure gradually decreases as blood flows through the arteries, arterioles, and capillaries. The pressure is lowest in the venules and veins, where blood returns to the heart.
