Question 1

Which of the following is the main circulatory fluid in our body?

Accepted Answer

Blood is the main circulatory fluid in our body. It flows through blood vessels and transports substances like digested food from the small intestine to other parts of the body. It also carries oxygen from the lungs to the cells and waste products away from the cells for removal.

Question 2

Which component of blood fights against germs that enter our body?

Accepted Answer

White Blood Cells (WBCs) fight against germs that enter our body. They act as part of the immune system, defending the body against infectious diseases and foreign invaders by engulfing them or producing antibodies.

Question 3

What is the function of blood platelets?

Accepted Answer

Platelets are responsible for the clotting of blood. When a person gets an injury and starts bleeding, platelets help form a blood clot at the wound site, which prevents further loss of blood and seals the cut.

Question 4

Which blood vessels carry oxygen-rich blood from the heart to all parts of the body?

Accepted Answer

Arteries carry oxygen-rich blood from the heart to all parts of the body. Since the blood flows at high pressure from the heart, arteries have thick, elastic walls to withstand this pressure.

Question 5

Which blood vessels have valves that allow blood to flow only towards the heart?

Accepted Answer

Veins are blood vessels that carry carbon dioxide-rich blood from all parts of the body back to the heart. They have valves that allow blood to flow only in one direction, towards the heart, preventing backflow.

Transportation in Animals and Plants — CBSE Class 7 Science Important Questions & Revision Notes