Page 98 - Ripples SCIENCE 7 - TEJPUR Edition 2024 Answer Key

6. How does sweating keep our body cool in summers?

Ans. Sweating helps keep our bodies cool during hot summers by releasing a watery fluid

called sweat, onto our skin. As this sweat evaporates, it takes away heat from our
body, cooling us down.

7. What is dialysis?
Ans. Dialysis is a medical treatment that helps remove waste products from the body of

people whose kidneys cannot function properly. It involves a machine used to clean

the blood & maintain proper balance of chemicals in the body.
8. What is the main function of a valve in the heart?

Ans. The valves present between different chambers of the heart ensure that the blood
flows only in a particular direction. They prevent the backflow of blood in the heart,

thereby maintaining a healthy blood circulation.

9. Name the organs of excretory system.
Ans. The organs of the excretory system include:

(a) Kidneys : Filter waste products & excess substances from the blood to form

urine.
(b) Ureters : Tubes that transport urine from the kidneys to the bladder.

(c) Bladder : Stores urine until it is excreted from the body through the urethra.

(d) Urethra : Tube through which urine exits the body from the bladder.
10. Name the four types of blood groups. Which blood group is known as ‘universal

donor’ and which is known as the ‘universal recipient’?
Ans. The four types of blood group are – A, B, AB and O.

‘O’ Blood group is known as ‘universal donor’ & ‘AB’ blood group is called ‘universal

receipient’.
F. Long-answer questions :

1. Explain the function of the kidney.
Ans. Function of the Kidney:

The kidneys remove urea from the blood through tiny filtering units called nephrons.

When blood that contains waste is brought to the kidneys, these nephrons remove
urea, salt and excess water from the blood. The filtered waste forms a liquid called

urine, which is transported to the urinary bladder via ureters. The purified blood

returns to the circulatory system.
2. Explain the function of the heart with the help of a diagram.

Ans. Heart pumps the blood in the blood vessels.

98