Science STD 7 Chapter 7: Transportation in Animals and Plants - Exercises
1. Match structures given in Column I with 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.
- (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
- xylem
- phloem
- stomata
- root hair
- (b) Water absorption through roots can be increased by keeping the plants
- in the shade
- in dim light
- under the fan
- covered with a polythene bag
4. Why is transport of materials necessary in a plant or in an animal? Explain.
Transportation of materials is necessary in both plants and animals to ensure that all cells receive the essential substances they need and that waste products are removed. In animals, the circulatory system transports digested food, oxygen, and hormones to all parts of the body and carries waste products like carbon dioxide and urea for removal. In plants, the vascular tissues (xylem and phloem) transport water and minerals from the roots to the leaves and food prepared in the leaves to all other parts of the plant, including the roots.
5. What will happen if there are no platelets in the blood?
If there are no platelets in the blood, the process of blood clotting would not occur. As a result, in case of an injury or a cut, bleeding would not stop, which could lead to excessive blood loss and become life-threatening.
6. What are stomata? Give two functions of stomata.
Stomata are tiny pores present on the surface of leaves. They are surrounded by guard cells which control their opening and closing. The two main functions of stomata are: (1) To allow the exchange of gases (carbon dioxide and oxygen) during photosynthesis and respiration. (2) To release excess water in the form of water vapour through the process of transpiration.
7. Does transpiration serve any useful function in the plants? Explain.
Yes, transpiration serves several useful functions in plants. It creates a suction pull, similar to sucking water through a straw, which helps to pull water and dissolved minerals from the roots up to great heights in tall trees. This process also helps to cool the plant, much like sweating helps to cool the human body. However, plants lose a lot of water through this process.
8. What are the components of blood?
Blood is composed of a fluid called plasma in which different types of cells are suspended. The main components are: (1) Red Blood Cells (RBCs) which contain haemoglobin to carry oxygen. (2) White Blood Cells (WBCs) that fight against germs. (3) Platelets that help in blood clotting.
9. Why is blood needed by all the parts of a body?
Blood is needed by all parts of the body because it functions as the body's primary transport system. It transports essential substances like digested food and oxygen to the cells for energy and growth. It also carries waste materials like carbon dioxide and other waste products from the cells to the excretory organs for removal. Without blood, the body's cells would not get the necessary nutrients and oxygen, and waste would accumulate, leading to cell death and organ failure.
10. What makes the blood look red?
The blood looks red due to the presence of a red pigment called haemoglobin. Haemoglobin is found in the red blood cells and binds with oxygen to transport it throughout the body.
11. Describe the function of the heart.
The heart functions as a continuous pump for the circulatory system. Its rhythmic contraction and relaxation allow it to pump blood, which carries various substances, to all parts of the body. The heart ensures that oxygen-rich blood is transported to the body's cells and carbon dioxide-rich blood is returned to the lungs for purification.
12. Why is it necessary to excrete waste products?
It is necessary to excrete waste products because they are toxic and harmful to the body. If they are allowed to accumulate, they can poison the cells and interfere with the normal functioning of the body, leading to various diseases or even death.
13. Draw a diagram of the human excretory system and label the various parts.
The human excretory system consists of two kidneys, two ureters, a urinary bladder, and a urethra. The diagram should show these parts clearly and label them accurately.
Suggested Activities and Projects
1. Find out about blood groups and their importance.
Outline: This activity involves researching different blood groups (A, B, AB, O) and their importance, especially for blood transfusions. You would learn that blood groups are determined by specific antigens on red blood cells and that a person must receive blood from a compatible group to prevent a dangerous reaction. Blood banks classify and store blood according to these groups to ensure safe transfusions.
2. When a person suffers from chest pain, the doctor immediately takes an ECG. Visit a doctor and get information about ECG. You may even look up an encyclopaedia or the internet.
Outline: This activity focuses on understanding the use of an ECG (Electrocardiogram). You would learn that an ECG is a test that records the electrical activity of the heart. A doctor uses it to check for heart rhythm abnormalities, heart attacks, or other heart conditions. The information collected would describe how the test is performed and what the results indicate.