Human Circulatory System Class-6 Srijan ICSE Biology Solutions Chapter-6

Human Circulatory System Class-6 Srijan ICSE Biology Solutions Chapter-6 Veer Bala Rastogi Srijan Publishers Solutions. We Provide Step by Step Solutions of  Fill in the blanks, Give functions, Define the following, Differentiate between the following, Match the following, True and False, MCQs and Answer these Questions of Veer Bala Rastogi Srijan Biology Publishers. Visit official Website CISCE for detail information about ICSE Board Class-6.

Human Circulatory System Class-6 Srijan ICSE Biology Solutions Chapter-6

Board ICSE
Class 6th
Subject Biology
Book Name Srijan
Chapter-6 Human Circulatory System
Unit-1 Human Circulatory System
Topic Solution of exercise questions
Session 2023-24

Human Circulatory System ICSE Class-6th Srijan

Biology Solutions Chapter-6

 A. Fill in the blanks with suitable words:

1. The red blood cells have red colour due to the presence of hemoglobin.

2. White blood cells are called soldiers of the body.

3. Pulmonary veins carry oxygenated blood.

4. Arteries have thick walls and narrow lumen.

5. The Capillaries are the fine connecting vessels between arteries and veins.

B. Give one word for the following:

Question: 1. The valves present on the opening between right auricle and right ventricle.

Answer: Tricuspid valve

Question: 2. The muscles that form heart walls.

Answer: The myocardium

Question: 3. The heart chamber that receives oxygenated blood from lungs.

Answer: Left atrium

Question: 4. The blood group which has both types of antigens.

Answer: Type AB

C. Define these terms:

Question: 1. Cardiac cycle

Answer: The cardiac cycle is a series of pressure changes that take place within the heart. These pressure changes result in the movement of blood through different chambers of the heart and the body as a whole.

Question: 2. Heartbeat

Answer: Heartbeat is the pulsation of heart. That is heartbeat is the regular movement of your heart as it pumps blood around your body.

Question: 3. Antigen

Answer: An antigen is any substance that causes your immune system to produce antibodies against it. This means your immune system does not recognize the substance, and is trying to fight it off. An antigen may be a substance from the environment, such as chemicals, bacteria, viruses, or pollen.

Question: 4. Antibody

Answer: Antibodies are proteins that protect you when an unwanted substance enters your body. Produced by your immune system, antibodies bind to these unwanted substances in order to eliminate them from your system.

D. Differentiate between the following:

Question: 1. Artery and vein


Arteries Veins
1. Arteries are bright red. 1. Veins are blue in color.
2. Arteries carry blood away from heart. 2. Veins carry blood towards the heart.
3. Arteries carry oxygenated blood 3. Veins carry deoxygenated blood.
4. Arteries are more muscular in comparative to veins 4. Veins are less muscular in comparative to arteries.
5. Arteries contain high blood pressure. 5. Veins contain low blood pressure
6. Arteries are divided into arterioles. 6. Veins are divided into venules.
Question: 2. RBC and WBC


1. They are called erythrocytes. 1. They are called leucocytes.
2. They are non-nucleated and biconcave. 2. They are nucleated and irregular in shape.
3. They are produced in the bone marrow. 3. They are produced in the lymph nodes, the spleen, etc.
4. Their life span is 120 days 4. Their life span is up to 120 days in the body.
Question: 3. Lub and dub sounds of heart


Lub sound Dub sound
1. The first sound of a heartbeat. 1. The second sound of a heartbeat.
2. The lub sound corresponds with ventricular systole. 2. The dub sound corresponds with atrial systole.
3. Closure of the atrioventricular valve produces a loud lub sound. 3. Closure of aortic and pulmonary valve produces soft dub sound.
Question: 4. Systole and diastole


Systole Diastole
1. It happens when the heart muscle contracts and the blood moves to the aorta and pulmonary artery. 1. It happens when the heart muscle relaxes between two contractions and the heart is filled with blood.
2. Systole reduces the volume of the heart as all the blood gets pumped out. 2. Diastole increases the heart volume and makes it normal as the blood comes back in.

E. Answer these questions:

Question: 1. What are the main parts of human circulatory system?

Answer: The parts of your circulatory system are your:

  • Heart, a muscular organ that pumps blood throughout your body.
  • Blood vessels, which include your arteries, veins and capillaries.
  • Blood, made up of red and white blood cells, plasma and platelets.
Question: 2. Describe the functions of blood in short.

Answer: The functions of blood in short:

1) It carries  and  in our body.
2) Nutrient and waste product are carried by it.
3) It protects our body from disease causing pathogens
4) If body gets injured it stop bleeding by making blood clots.
5) Carries antigens and antibodies.
6) Maintains  body temperature.

Question: 3. What is ABO blood group system? Who discovered it?

Answer: AB Blood Group:

  1. Karl Landsteiner discovered in the AB blood group in 1901.
  2. In 1900 he discovered that red blood cells agglutinate when mixed in the test tube with serum from a different person.
  3. In 1909 identified and named the blood group A, AB, B, and O.
  4. He received the Nobel Prize in 1930.
  5. According to the AB blood group, there are three types of blood groups A, B, and O depending on the presence or absence of antigens A, B, and O.
Question: 4. What is heartbeat? Why does the heart make lub-dub sound?

Answer: Heartbeat is the pulsation of heart. That is heartbeat is the regular movement of your heart as it pumps blood around your body.

This sound comes from the valves shutting on the blood inside the heart. The first sound (the lub) happens when the mitral and tricuspid valves close. The next sound (the dub) happens when the aortic and pulmonary valves close after the blood has been squeezed out of the heart.

Question: 5. How is oxygen transported by blood in animals?

Answer: Red blood cells contain haemoglobin which helps in transporting oxygen in animals. RBCs are flattened discs, which gives them a much greater surface area with which to exchange oxygen in the lungs and with body cells.

Question: 6. What are the ways for keeping the heart healthy?

Answer: The ways for keeping the heart healthy:

  • Eat healthy.
  • Get active.
  • Stay at a healthy weight.
  • Quit smoking and stay away from secondhand smoke.
  • Control your cholesterol and blood pressure.
  • Drink alcohol only in moderation.
  • Manage stress.

F. State whether the following statements are true or false. If false, rewrite the correct form of statements:

Statements True/False
1. Clumping occurs between mismatched blood groups. T
2. Capillary wall is formed of many layers of cells. F
3. Veins have valves in their lumen. T
4. Low fat diet is good for heart. T
5. Antigens are present in the plasma and antibodies on the RBCs. F
6. Blood in the arteries flows under pressure and with jerk. T

G. Match the columns:

Column A Column B
1. Blood group O (a) Joint relaxation
2. Blood clotting (b) Universal donor
3. Veins (c) Blood platelets
4. Aorta (d) Valves
5. Diastole (e) Semilunar valves


Column A Column B
1. Blood group O (a) Universal donor
2. Blood clotting (b) Blood platelets
3. Veins (c) Valves
4. Aorta (d) Semilunar valves
5. Diastole (e) Joint relaxation

H. Encircle the odd one out. Give reasons for your choice:

Question: 1. Arteries, veins, capillaries, ureters

Answer: Odd one out: ureters

Give reasons: This is because rest all are types of blood vessels.

Question: 2. Heartbeat, pulse, blood pressure, cardiac cycle

Answer: Odd one out: blood pressure

Give reasons: heartbeat, pulse ,cardiac cycle -these all are functions of heart . But blood pressure is not a function of heart.

Question: 3. RBCs, WBCs, antibodies, platelets

Answer: Odd one out: antibodies

Give reasons: RBC, platelets and WBC are three types of blood cells whereas anti-A is a type of antibody present in the blood plasma.

I. Give reasons for the following:

Question: 1. Ventricles have thicker walls than auricles. 

Answer: Ventricles have thicker walls than auricles because they have to pump blood to different organs and the pressure with which the blood flows through them is more than the auricles.

Question: 2. Openings of auricles into ventricles are guarded by valves.

Answer: Atrioventricular valves:

  1. Valves are connective tissue flaps that are linked to the papillary muscles of the ventricles by multiple connective tissue cords.
  2. They ensure unidirectional flow and prevent the backflow of blood.
  3. The valves present between the auricles and ventricles are called atrioventricular valves/ cuspid valves.
  4. These are of two types: Tricuspid and bicuspid (Mitral) valves.
  5. Tricuspid valves are present between the right auricle and ventricle.
  6. Bicuspid valves are present between the left auricle and ventricle.
  7. When auricles contract, the cuspid valves open.
Question: 3. Arteries have thick walls.

Answer: Arteries carry oxygenated blood from the heart to the different body parts. Blood emerges from the heart under high pressure. In order to withstand this pressure, arteries have thick walls.

Question: 4. Leucocytes are called soldiers of our body.

Answer: Leukocytes are white blood cells that lack hemoglobin. Leukocytes are of two types, namely granulocytes and agranulocytes. They are responsible for protecting our bodies from infections and foreign invaders. They are found in blood and the lymphatic system. They are the first to act in case of an infection and thus are referred to as soldiers of the human body.

Question: 5. Valves are present in veins but not in arteries.

Answer: Arteries carry blood from the heart to the different parts of the body and therefore it needs to be in higher pressure. For this, they have a narrower lumen. This causes the blood in the arteries to have higher pressure and due to this high pressure there is less chance of backflow of blood and valves need not be present. However, the pressure of the blood flowing through the veins is not high. So, to prevent backflow of blood valves are present in the veins.

J. Multiple Choice Questions:

1. Blood cells which transport oxygen are

(a) Platelets

(b) WBCs

(c) RBCs

(d) Thrombocytes

Answer: option (c) RBCs is correct.

2. The blood group which can receive blood from all the four blood groups is

(a) O

(b) AB

(c) A

(d) B

Answer: option (b) AB is correct.

3. Human heart is

(a) two-chambered

(b) three-chambered

(c) four-chambered

(d) five-chambered

Answer: option (c) four-chambered is correct.

4. Pulmonary vein carries

(a) Oxygenated blood

(b) Deoxygenated blood

(c) Ammonia-rich blood

(d) Glucose-rich blood

Answer: option (a) Oxygenated blood is correct.

5. Sphygmomanometer is used to measure

(a) Heartbeat

(b) Pulse rate

(c) Blood pressure

(d) Blood group

Answer: option (c) Blood pressure is correct.

6. Pulse rate is

(a) 72 times per minute

(b) 72 times per second

(c) 78 times per minute

(d) 78 times per second

Answer: option (a) 72 times per minute is correct.

K. Diagram-based questions:

1. Draw labelled diagrams of three types of blood vessels showing difference between their lumen.

three types of blood

There are three types of blood vessels: Arteries carry blood away from your heart. Veins carry blood back toward your heart. Capillaries, the smallest blood vessels, connect arteries and veins.

— : End of  Human Circulatory System Class-6 Srijan ICSE Biology Solutions Chapter-6:–

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