1. Match the structures given in Column I with the functions given in Column II.
Column I | Column II
(i) Stomata | (b) Transpiration
(ii) Xylem | (d) Transport of water
(iii) Root hairs | (a) Absorption of water
(iv) Phloem | (c) Transport of food
2. Fill in the blanks.
(i) The blood from the heart is transported to all parts of the body by the arteries.
(ii) Haemoglobin is present in red blood cells (RBCs).
(iii) Arteries and veins are joined by a network of capillaries.
(iv) The rhythmic expansion and contraction of the heart is called heartbeat.
(v) The main excretory product in human beings is urea.
(vi) Sweat contains water and salts.
(vii) Kidneys eliminate the waste materials in the liquid form called urine.
(viii) Water reaches great heights in the trees because of suction pull caused by transpiration.
3. Choose the correct option:
(a) In plants, water is transported through
(i) xylem
(b) Water absorption through roots can be increased by keeping the plants
(iii) under the fan
4. Why is transport of materials necessary in a plant or in an animal? Explain.
Answer: Transport of materials is necessary because plants and animals need food, water, and oxygen to reach all parts of their body. In animals, the blood carries these materials to the cells and also removes waste products like carbon dioxide. In plants, water and minerals are transported to the leaves, and food made in the leaves is sent to other parts of the plant.
5. What will happen if there are no platelets in the blood?
Answer: If there are no platelets in the blood, when we get a cut or injury, the blood will not clot. This can lead to excessive bleeding, as platelets help in forming clots to stop the bleeding.
6. What are stomata? Give two functions of stomata.
Answer: Stomata are tiny openings on the surface of leaves. They help in the following ways:
- They allow gases like oxygen and carbon dioxide to enter and leave the plant.
- They help in the process of transpiration, where water is released from the plant.
7. Does transpiration serve any useful function in the plants? Explain.
Answer: Yes, transpiration helps plants by cooling them down, much like sweating cools our bodies. It also creates a suction pull that helps move water from the roots to the leaves.
8. What are the components of blood?
Answer: Blood is made up of four main components:
- Plasma: The liquid part that carries nutrients, hormones, and waste products.
- Red Blood Cells (RBCs): They carry oxygen due to the presence of haemoglobin.
- White Blood Cells (WBCs): They fight against germs and infections.
- Platelets: They help in clotting the blood when we get a cut or injury.
9. Why is blood needed by all the parts of a body?
Answer: Blood is needed because it carries oxygen and nutrients to all the cells of the body, helping them to function properly. It also carries away waste products like carbon dioxide.
10. What makes the blood look red?
Answer: Blood looks red because of a substance called haemoglobin, which is found in red blood cells. Haemoglobin binds with oxygen, giving the blood its red color.
11. Describe the function of the heart.
Answer: The heart is a muscular organ that pumps blood throughout the body. It has four chambers that keep the oxygen-rich blood and the carbon dioxide-rich blood separate. The heart beats continuously, sending blood to the lungs to collect oxygen and then pumping it to the rest of the body.
12. Why is it necessary to excrete waste products?
Answer: It is necessary to excrete waste products because if they build up in the body, they can be harmful and make us sick. The body removes waste through the excretory system, which filters the blood and sends waste out in the form of urine.
13. Draw a diagram of the human excretory system and label the various parts.
You will need to draw the diagram based on the figure provided in your textbook (Figure 7.6). Be sure to label the kidneys, ureters, urinary bladder, and urethra.