7. Transportation in Animals and Plants

Give reasons for the following:

Q1. Why can’t we survive without haemoglobin?

Ans:

1. Haemoglobin is a red pigment present in the red blood cells (RBC’s).
2. It binds with oxygen to transport it to all the parts of the body & the cells.
3. It will be difficult to provide oxygen to all the cells of the body without haemoglobin.
4. Thus, haemoglobin is very important for the body.

Q2. Why arteries have thick elastic walls?

Ans:

1. Arteries are blood vessels that carry oxygen-rich blood from the heart to all parts of the body.
2. The blood flow in the arteries is very rapid & at a high pressure.
3. Hence, the arteries have thick elastic walls.

Q3. Why do veins have valves?

Ans:

1. Veins are blood vessels which carry carbon dioxide-rich blood from all parts of the body back to the heart.
2. The veins have thin walls.
3. Hence, the veins have valves which allow blood to flow only towards the heart & thus prevent back flow of blood.

Q4. Why there is partition in the heart?

Ans:

1. The heart has four chambers.
2. The upper two chambers are called atria & the lower two chambers are called ventricles.
3. To avoid mixing of oxygenated & deoxygenated blood, the heart has partition between the chambers.

Q5. Sometimes in summer, white patches are formed on our clothes, especially in areas like underarms. Why?

Ans:

1. We sweat to maintain body temperature on a hot summer day.
2. The sweat contains water and salts.
3. These marks are left by salts present in the sweat.

Answer the following in short

Q1. What is plasma & its function?

Ans:

1. Blood is made up of a yellowish colour fluid called plasma.
2. It is 90% water.
3. Different types of cells & other components are suspended in the plasma.

Q2. What are the types of blood vessels?

Ans:

1. There are three types of blood vessels.
2. They are arteries, veins & capillaries.

Q3. What are capillaries?

Ans:

1. The arteries divide into smaller thin tube-like blood vessels on reaching the tissues.
2. These are called as capillaries.
3. The capillaries join to form veins which empty deoxygenated blood into the heart.

Q4. Where is the heart located & what is its size?

Ans:

1. The heart is located in the chest cavity with its lower tip slightly tilted towards the left.
2. It is roughly the size of our fist.

Q5. What is the function of pulmonary artery?

Ans:

The pulmonary artery carries deoxygenated blood from the right ventricle of the heart to the lungs.

Q6. What is the function of pulmonary vein?

Ans:

The pulmonary vein carries oxygenated blood from the lungs to the left atrium of the heart.

Q7. What is a heartbeat?

Ans:

1. The walls of the chambers of the heart are made up of muscles which contract and relax rhythmically.
2.  A rhythmic contraction followed by its relaxation constitutes a heartbeat.

Q8. What the human urine consists of?

Ans:

1. An adult human being normally passes about 1 to 1.8 litre of urine in 24 hours.
2. The urine consists of 95% water, 2.5% urea and 2.5% other waste products.

Q9. What is the function of the circulatory system?

Ans:

1. The circulatory system transports oxygen & nutrients to all the parts of the body.
2. It helps to dispose of waste products from the cells & various parts of the body.

Q10. What is excretion?

Ans:

Excretion is the process of removal of wastes produced in the cells of the living organisms.

Q11. What happens when you sweat?

Ans:

1. Sweat consists of water and salts which evaporate removing excess heat from the body.
2. Thus, sweating helps to cool the body.

Q12. What do kidneys do?

Ans:

1. Kidneys filter waste from the blood.
2. They produce urine to excrete waste.

Q13. How do root hair help in circulation in the plants?

Ans:

1. Root hair is in direct contact with water in the soil particles. 
2. They increase the surface area of the roots which increases absorption of water & minerals from the soil.

Q14. What is xylem & phloem?

Ans:

1. Xylem is the vascular tissue that transports water & minerals from the roots to the leaves in the plants.
2. Phloem is the vascular tissue that transports food in plants.

Q15. What is transpiration?

Ans:

1. Some water evaporates through the stomata present on the surface of the leaves.
2. This loss of water is called transpiration.

Answer the following questions

Q1. What is blood? What is the importance / function of blood?

Ans:

1. Blood is the fluid which flows in blood vessels.
2. It transports substances like digested food from the small intestine to the other parts of the body.
3. It carries oxygen from the lungs to the cells of the body.
4. It also transports waste for removal from the body.

Q2. What is a stethoscope & how is it used?

Ans:

1. Stethoscope is a device which amplifies the sound of the heart.
2. It consists of a chest piece that carries a sensitive diaphragm, two ear pieces and a tube joining the parts.
3. A doctor uses a stethoscope to listen to the sound of the heart to understand the condition of the heart.

Q3. How does circulation take place in hydra?

Ans:

1. Animals like hydra or sponges do not possess any circulatory system.
2. The water in which they live carries food and oxygen as it enters their bodies.
3. The water carries away waste materials and carbon dioxide as it moves out.
4. Thus, these animals do not need a circulatory fluid like the blood.

Q4. Explain the process of excretion in human body.

Ans:

The process of excretion in human body is as follows:

1. The blood containing both useful and harmful substances reaches the kidneys.
2. The blood capillaries in the kidneys filter this blood.
3. The useful substances are absorbed back into the blood.
4. The wastes are dissolved in water are removed as urine.
5. Then tubes called ureters pass the urine from into the urinary bladder.
6. Urine is stored in the bladder and is passed out through the urinary opening at the end of a muscular tube called urethra.
7. Thus, the kidneys, ureters, bladder and urethra form the excretory system.

Q5. What is dialysis?

Ans:

1. Sometimes a person’s kidneys may stop working due to infection or injury.
2. As a result of kidney failure, waste products start accumulating in the blood.
3. Such persons cannot survive unless their blood is filtered periodically through an artificial kidney.
4. This process is called dialysis.

Q6. Explain the process of circulation in plants.

Ans:

1. The plants have pipe-like vessels made of special cells, forming the vascular tissue. 
2. The vascular tissue for the transport of water and nutrients in the plant is called the xylem.
3. The xylem forms a continuous network of channels that connects roots to the leaves through the stem and branches. 
4. The food is transported to all parts of the plant through the vascular tissue called the phloem.
5. Thus, xylem and phloem transport substances in plants & form the circulatory system.

Q7. Difference between arteries & veins.

Ans: