The Circulatory System
Solutions for Biology, Class 6, ICSE
Choose The Odd One
1 questionGiven below are sets of four terms. Choose the odd one and write the category of the remaining terms :
- Erythrocytes, Leukoplasts, Leukocytes, Thrombocytes
- Arteries, Atria, Capillaries, Veins
- Heart, Kidney, Blood vessels, Blood
- RBCs, WBCs, Haemoglobin, Platelets
- Diaphragm, Left atrium, Right ventricle, Pulmonary artery
Answer:
Odd one — Leukoplasts
Category of the remaining terms — Corpuscles (Blood cells)Odd one — Atria
Category of the remaining terms — Blood vesselsOdd one — Kidney
Category of the remaining terms — Parts of Circulatory SystemOdd one — Haemoglobin
Category of the remaining terms — Corpuscles (Blood cells)Odd one — Diaphragm
Category of the remaining terms — Parts of the heart
Fill In The Blanks
1 questionFill in the blanks with suitable words :
- The colour of a red blood cell is due to ...............
- The two lower chambers of the heart are called ...............
- The blood plasma contains dissolved substances such as ............... and ...............
- The ............... artery takes the blood from the ventricles to the lungs.
- The instrument used to find out the blood pressure is known as ...............
- The blood loaded with carbon dioxide from the body comes into the ............... of the heart.
- The oxygen-rich blood from the lungs comes into ............... of the heart.
- The oxygen-rich blood is pumped into different parts of the body through ...............
- The carbon dioxide loaded blood from the right ventricle is pumped into the lungs through ............... artery.
Answer:
- Haemoglobin
- Ventricles
- Nutrients, Proteins, waste products and Hormones
- Pulmonary
- Sphygmomanometer
- Right Auricle
- Left Ventricles
- Aorta
- Pulmonary
Long Answer Questions
9 questionsAnswer:
The three kinds of blood vessels found in human beings are Arteries, Veins and Capillaries.
Below diagram shows the differences between Artery, Vein and Capillaries:

Arteries | Veins | Capillaries |
---|---|---|
An artery is a vessel which carries the blood away from the heart to other parts of the body. | A vein is a vessel which carries the blood from an organ towards the heart. | Capillaries are the terminal branches of an artery, which rejoin to form a vein. |
An artery has thick, elastic and more muscular walls. | A vein has thin and less muscular walls with valves. | Walls of the capillary are made up of single layer of cells (endothelium) with no muscles. |
The blood in it flows with jerk and under great force. | The valves prevent the back flow of the blood flowing towards the heart. | The wall of capillary is very thin, to enable an exchange of nutrients waste products and gases between the blood and the body fluids. |
Answer:
Difference between White blood cells and Red blood cells:
White Blood Cells | Red Blood Cells |
---|---|
WBCs are amoeboid having irregular shape. | RBCs are circular or biconcave disc shaped. |
WBCs have distinct oval or lobed nucleus. | RBCs do not have nucleus at maturity. |
WBCs are larger than RBCs. | RBCs are small in size. |
RBCs have red colour due to the presence of haemoglobin protein. | WBCs are colourless and they lack haemoglobin. |
RBCs carry oxygen from lungs to all the body tissues and cells and remove carbon dioxide produced in the cells and carry it back to the lungs. | WBCs provide immunity by destroying the disease causing germs and producing antibodies. |
Answer:
These blood vessels seen on the outside of the hands are Veins. Usually, arteries are deeply placed in the body whereas Veins are placed more superficially.
Given alongside is a diagram of human heart showing its internal structure. Label the parts marked 1 to 5, and answer the following questions.

(a) Which type of blood is carried by the blood vessel marked 2?
(b) Name the main artery which takes the blood from heart to different parts of the body?
(c) Which chamber of the heart receives oxygenated blood from the lungs?
Answer:
The marked parts are:
- Left pulmonary artery
- Superior vena cava
- Left pulmonary vein
- Right auricle
- Left ventricle
a) Deoxygenated blood is carried by the blood vessel marked 2 (Superior vena cava).
b) Aorta
c) Left auricle
Answer:
Differences between arteries and veins on the basis of their structure:
Arteries | Veins |
---|---|
Arteries have thick, elastic and muscular walls to withstand high pressure. | Veins have thin and less muscular walls as the blood pressure is lower. |
They lack valves (except the pulmonary trunk and the aorta). | Valves are usually present to prevent the backflow of blood. |
Arteries are usually, deeply placed in the body. | Veins are usually placed more superficially. |
Answer:
Differences between atria and ventricles on the basis of their location in the heart:
Atria | Ventricles |
---|---|
The atria are the two upper chambers of the heart. | The ventricles are the two lower chambers of the heart. |
Answer:
Differences between Blood groups 'AB' and 'O' on the basis of antigens:
Blood group 'AB' | Blood group 'O' |
---|---|
The persons whose RBCs have both types of antigens, i.e. both A and B, belong to the 'AB' blood group. | The persons whose RBCs have no antigens, i.e., neither A nor B have the 'O' blood group. |
Answer:
Differences between pulmonary and systemic circulation on the basis of direction of blood flow:
Pulmonary Circulation | Systemic Circulation |
---|---|
In pulmonary circulation, the blood flows from the heart to the lungs and back to the heart. | In systemic circulation, the blood flows from the heart to the entire body (except lungs) and back to the heart. |
Answer:
Differences between pulmonary artery and pulmonary vein on the basis of the kind of blood they carry:
Pulmonary Artery | Pulmonary Vein |
---|---|
The pulmonary artery carries deoxygenated blood from the heart to the lungs. | The pulmonary vein carries oxygenated blood from the lungs back to the heart. |
Match The Following
1 questionAnswer:
Column A | Column B |
---|---|
(i) Haemoglobin | (c) Oxygen carrier |
(ii) Heart | (d) Pumping organ |
(iii) Leukocytes | (a) Antibodies |
(iv) Atria | (e) Receiving chambers |
(v) Ventricles | (b) Distributing chambers |
Multiple Choice Questions
10 questionsAnswer:
Narrow tube made up of endothelium only
Reason — Blood capillary is narrow blood vessel whose walls have a single layer of cells called endothelium.
Answer:
Vena cavae
Reason — The Superior Vena Cava and the Inferior Vena Cava brings deoxygenated blood from the upper and lower parts of the body to the right auricle of the heart.
Short Answer Questions
15 questionsAnswer:
Difference between Platelets and WBCs:
Platelets | WBCs |
---|---|
Platelets help in clotting of blood. | WBCs provide immunity by destroying the disease causing germs and producing antibodies. |
Platelets are the smallest of the blood cells. | WBCs are larger than RBCs and Platelets. |
Platelets does not have a nucleus. | WBCs have a distinct oval or lobed nucleus. |
Answer:
Difference between Pulmonary artery and Pulmonary vein:
Pulmonary artery | Pulmonary vein |
---|---|
The Pulmonary artery arises from the right ventricle of the heart. | The Pulmonary vein drains blood in the left atrium of the heart. |
It carries deoxygenated blood from the right auricle of the heart to each lung. | It carries oxygenated blood from each lung to the left atrium of the heart. |
Answer:
Difference between Vena cava and Aorta:
Vena cava | Aorta |
---|---|
Vena cava is a large vein. | Aorta is the largest artery. |
It carries deoxygenated blood from the upper and lower parts of the body to the right auricle of the heart. | It leaves the left auricle of the heart carrying oxygenated blood to all parts of the body through its branches. |
Answer:
Difference between RBC and WBC:
RBC | WBC |
---|---|
RBC do not have nucleus at maturity. | WBC have a large distinct oval or lobed nucleus . |
WBC are larger than RBC. | RBC are small in size. |
RBC have red colour due to the presence of haemoglobin protein. | WBC are colourless and they lack haemoglobin. |
RBC carry oxygen from lungs to all the body tissues and cells and remove carbon dioxide produced in the cells and carry it back to the lungs. | WBC provide immunity by destroying the disease causing germs and producing antibodies. |
Answer:
Three differences between an Artery and a Vein are:
Artery | Vein |
---|---|
Arteries carry blood away from the heart to various body parts. | Veins carry blood from different body parts to the heart. |
Arteries have thick elastic and more muscular walls. | Veins have thin and less muscular walls. |
Arteries carry oxygenated blood (except the pulmonary artery). | Veins carry deoxygenated blood (except the pulmonary vein). |
Answer:
Blood is a red coloured fluid which consists of two parts:
- Liquid part — The liquid part of the blood is called Plasma. Plasma is yellow in colour. 90% of Plasma is water and the remaining 10% consists of dissolved proteins, nutrients, waste product and hormones.
- Cellular part — The cellular part of the blood is called Corpuscles. The corpuscles are of three types:
- Red Blood Cells (RBCs) — RBCs are also called as Erythrocytes. They carry oxygen from lungs to all the body tissues and cells and remove carbon dioxide produced in the cells and carry it back to the lungs. RBCs are circular or biconcave disc shaped. A mature RBC does not contain nucleus. Haemoglobin present in RBCs helps in transport of oxygen and gives them the red colour.
- White Blood Cells (WBCs) — WBCs are also called Leukocytes. They are colourless and lack haemoglobin. They are larger than RBCs and have a distinct oval or lobed nucleus. WBCs provide immunity by destroying the disease causing germs and producing antibodies
- Platelets — The platelets are also called Thrombocytes. They are round in shaped and the smallest in size. They help in the clotting of blood which prevents excessive blood loss and direct entry of disease causing germs into the blood through cuts and wounds.
Answer:
Haemoglobin is an iron and protein compound present in the Red Blood Cells (RBCs). It acts as the Oxygen carrier as it binds with Oxygen transporting it to all the body tissues and cells. It also helps to remove carbon dioxide produced in the cells and carry it back to the lungs.
Answer:
Dengue fever is one such disease in which the number of platelets reduces to 25,000 - 30,0000 per cu mm of blood. The major symptoms of dengue are high fever, rashes or red spots on body, vomiting, pain in abdomen or back of the eyes and muscles.
Answer:
- Blood, Blood vessels and Heart
- Arteries, Veins and Capillaries
- Erythrocytes (RBCs), Leukocytes (WBCs), Thrombocytes (Platelets)
- Pulmonary Circulation and Systemic Circulation
- A, B, AB, and O
Answer:
Haemoglobin — Haemoglobin is an iron and protein compound that is found within the Red Blood cells. It acts as the "oxygen-carrier".
Capillaries — Capillaries are the terminal branches of an artery, which rejoin to form a vein.
Aorta — The aorta is the largest artery in the body and carries oxygenated blood from the left ventricle to all parts of the body through its branches.
Universal donor — A person with O blood group can give blood to a person of any blood type and is therefore called a universal donor.
Blood pressure — The pressure exerted by the blood on the walls of the arteries while flowing through them is called blood pressure.
Correct the following statements by changing the first/ last word only :
- Robert Hooke identified the different types of blood groups.
- A faster heart beat is usually an indication of hypotension.
- WBCs produce special substances called antigens.
- Thrombocytes contain haemoglobin.
- Arteries possess valves.
Answer:
- Karl Landsteiner identified the different types of blood groups.
- A faster heart beat is usually an indication of hypertension.
- WBCs produce special substances called antibodies.
- Erythrocytes contain haemoglobin.
- Veins possess valves.
Answer:
Erythrocytes contain an iron and protein compound called Haemoglobin that acts as the "oxygen-carrier".
The Thrombocytes help in the clotting of blood which prevents excessive blood loss and direct entry of disease causing germs into the blood through cuts and open wounds.
Arteries are crucial blood vessels that carry the blood away from the heart (oxygenated blood) to different parts of the body.
The vena cava's primary role is to return deoxygenated blood from the body back to the heart.
The heart, acting as a pump, pushes and receives the blood to and from the whole body through the blood vessels.