Column I	Column II
(i) Stomata	(a) Absorption of water
(ii) Xylem	(b) Transpiration
(iii) Root hairs	(c) Transport of food
(iv) Phloem	(d) Transport of water
	(e) Synthesis of carbohydrates

Ans:

(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.

1. The blood from the heart is transported to all parts of the body by the _________.

Ans: Arteries

1. Haemoglobin is present in _________ cells.

Ans: Red blood

1. Arteries and veins are joined by a network of _________.

Ans: Capillaries

1. The rhythmic expansion and contraction of the heart is called _________.

Ans: Heartbeat

1. The main excretory product in human beings is _________.

Ans: Urea

1. Sweat contains water and _________.

Ans: Salts

1. Kidneys eliminate the waste materials in the liquid form called _________.

Ans: Urine

1. The water reaches great heights in the trees because of suction pull caused by _________.

Ans: Transpiration

3. Choose the correct option:

1. In plants, water is transported through
2. xylem
3. phloem
4. stomata
5. root hair

Ans: (i) xylem

Xylem is a type of vascular tissue in plants that helps in the transport of water along with the dissolved nutrients from roots to other parts of the plant.

1. Water absorption through roots can be increased by keeping the plants
2. in the shade
3. in dim light
4. under the fan
5. covered with a polythene bag

Ans: (iii) under the fan

By placing the plants under a fan, there is an increase in the loss of water by transpiration, which in turn increases the rate of absorption of water through the roots.

4. Why is the transport of materials necessary in a plant or in an animal? Explain.

Ans:

• The transport of materials is important in a plant or in an animal, because their cells, which is the basic unit of life, require a constant supply of nutrients, oxygen, and water for the production of energy and its release during respiration. The cells need nutrients and oxygen for their metabolic processes.
• Also, transportation is needed to carry away the waste products produced by the cells due to their metabolic activities.
• Thus without transportation, the cells will neither receive the nutrients and oxygen nor be able to remove their metabolic wastes.

5. What will happen if there are no platelets in the blood?

Ans: The main role of platelets in our body is to help in the clotting of blood that helps to stop any bleeding. Without platelets, clotting will not occur. Thus, if an injury or a cut happens on the body, without platelets to form a clot, there will be severe blood loss due to excessive bleeding, which can also result in death.

6. What are stomata? Give two functions of stomata.

Ans: Stomata are the tiny openings in the surface of plants, found mainly on the lower surface leaves, and are also sometimes found on the plant stems too. Stomata are pores surrounded by specialised parenchymal cells, called guard cells that are used to control the gas exchange with the change in environmental conditions.

Stomata have two main functions:

• They help in gas exchange for the processes of respiration and photosynthesis.
• They also help in regulating water movement through transpiration.

7. Does transpiration serve any useful function in plants? Explain.

Ans:

• Transpiration is the movement of water through a plant and its evaporation from leaves. Simply put, it is the loss of water from a plant in the form of water vapour. Thus transpiration serves a very useful function in plants.
• This loss of water from the aerial parts of the plant creates a ‘transpiration pull’ that helps in the rise of water absorbed by the roots to higher parts of the plant.
• Another useful function of transpiration is helping in the cooling effect of plants, preventing drying out in the hot sun.

8. What are the components of blood?

Ans: Blood has two parts:

1. Fluid part – Plasma, which is majorly composed of water and contains chemicals, proteins, enzymes, salts, and gases dissolved in it.
2. Cellular part – RBC, WBC, and platelets.
   1. RBCs – Red Blood Cells, which are responsible for carrying oxygen and carbon dioxide with the help of haemoglobin to and from the cells.
   2. WBCs – White Blood Cells, which are a part of the immune system and maintain the immune response.
   3. Platelets are responsible for the clotting of blood.

9. Why is blood needed by all the parts of a body?

Ans:

• Blood is a connective tissue that connects all parts of the body.
• Blood helps to carry oxygen from the lungs to the cells and carbon dioxide produced by the cells is carried away from them to the lungs.
• It also helps to carry nutrients to various parts of the body for their absorption.
• Blood contains plasma that helps in clotting. It also helps in maintaining body temperature.
• WBCs that are responsible for the immune response are present in the blood, which helps us fight against diseases.
• Blood is also involved in the transport of hormones and the waste materials produced by the cells.

10. What makes the blood look red?

Ans: Blood appears red due to the presence of a pigment called haemoglobin, in the red blood cells. Haemoglobin is a protein complex containing iron that helps in the transport of oxygen in the human body. Iron is found abundant in our blood, which tends to reflect red light, making the blood look red. Thus we can say that haemoglobin makes the blood look red.

11. Describe the function of the heart.

Ans:

• The heart is said to be a vital organ in our body, which functions as a pump, pumping blood throughout the body.
• The heart is a part of the human circulatory system through which it pumps blood to transport nutrients, hormones, and oxygen to the cells via systemic circulation, and transports away carbon dioxide and other waste materials produced by the cells for their elimination.
• The heart pumps oxygenated blood from the lungs to organs and deoxygenated blood from the organs to the lungs for gas exchange.
• The heart also maintains blood pressure.

12. Why is it necessary to excrete waste products?

Ans: Waste products are produced as a result of metabolic processes in the cells, and they tend to be toxic. If they are not excreted, it will result in their buildup and accumulation in the cells that can result in toxicity and cause damage to cells and organs by preventing them from functioning normally. Thus we need to eliminate these waste products from our body by the process of excretion, with the help of kidneys.

13. Draw a diagram of the human excretory system and label the various parts.

Ans: