NCERT Class 11-Biology: Chapter –18 Body Fluids and Circulation Part 7

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Question 3:

Explain different types of blood groups and donor compatibility by making a table.


1. There are two types of blood grouping which are ABO and Rh.

2. ABO grouping is based on the presence or absence of two antigens on the RBC’s which are A and B.

3. These are three alleles and .

4. Gene Codes for blood group A

5. Gene Codes for blood group B.

6. Gene Codes for blood group O.

7. Gene Codes for blood group AB.

8. People with blood group A, have antigen A on the surface of the RBC’s and produce antibodies against blood group B.

9. People with blood group B have antigen B on the surface of the RBC’s and produce antibodies against blood group A.

10. People with blood group AB have antigen A and B on the surface of the RBC’s and produce no antibodies.

11. People with blood group O have no antigens on the surface of RBC’s and produce antibodies against both A and B blood group.

People with Blood Group O
People with blood group O

Blood Group


Antigenon RBC surface

Antibodies against

Donate blood to

Receive Blood from




A & AB

A & O




B & AB

B & O





AB, A,B & O



A & B

A, B & AB


13. This shows that blood group AB is a universal recipient and blood group O is a universal donor.

Question 4:

Write short note on the following

a. Hypertension

b. Coronary Artery Disease


a. Hypertension:

It is the condition in which there is a constant increase in the normal blood pressure.It affects all the vital organs like heart, kidney and brain etc. Blood pressure equal to or above is considered hypertension.

Types of Hypertension:

1. Primary Hypertension: It is also known as Idiopathic Hypertension because the specific cause of the increased blood pressure is not known.

2. Secondary Hypertension: It is the type of hypertension with a known cause.

Risk Factors:

1. Alcohol

2. Diabetes

3. Obesity

4. Smoking

5. Excessive Sodium Intake


1. Increased intake of water.

2. Decreased intake of sodium or table salt.

3. Stress and Caffeine should be avoided.

b. Coronary Artery Disease:

Narrowing of the arterial lumen due to the build-up of fats and cholesterol which decreases the supply of oxygen to the body organs. It may also lead to the damaging of heart muscles.

Risk Factors:

1. Obesity

2. Smoking

3. Excess fat intake

4. Hereditary


1. Regular exercise

2. Eating healthy

3. Vitamin supplement

4. Aspirins or blood thinners

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