Solution of Life Processes (Page No - 74 (Part - 2))- Biology by Lakhmir Singh, Class 10 | Extra Documents, Videos & Tests for Class 10 PDF Download

Question 52:
Describe the working of human blood circulatory system with the help of a suitable diagram which shows all the steps involved.
Solution :
Working of Human blood circulatory system takes place in the steps below:
(i) When the muscles of all the four chambers are relaxed, the pulmonary vein brings the oxygenated blood from the lungs in the left atrium of the heart.
(ii) When the left atrium contracts, the oxygenated blood is pushed into the left ventricle through valve V1.
(iii) When the left ventricle contracts, the oxygenated blood enters the main artery called aorta from which it goes to the different body organs through small branches called arterioles and capillaries. (iv) The main artery carries the blood to all the organs of the body head, arms etc except the lungs. The oxygenated blood gives off oxygen, digested food and dissolved materials to the body cells. The carbon dioxide produced in the cells enters the blood. The deoxygenated blood enters main vein called vena cava which carried it to the right atrium of the heart.
(v) When the right atrium contracts, the deoxygenated blood enters right ventricle through valve V2.
(vi) When the right ventricle contracts, the deoxygenated blood enters the lungs through pulmonary artery and releases carbon dioxide and absorbs fresh oxygen from air. The blood becomes oxygenated again and is sent to the left atrium of heart by pulmonary vein for circulation in the body. This whole process is repeated continuously. 

Diagram to show blood circulation in human body

Question 53:
(a) Name the red pigment which carries oxygen in the blood.
(b) Why is it necessary to separate oxygenated and deoxygenated blood in mammals and birds ?
(c) How many chambers are there in the heart of : (i) an amphibian, (ii) a mammal, and (iii) a fish ?
(d) Describe the circulatory system in a fish.
Solution :
(a) Haemoglobin.
(b) It is necessary to separate the oxygenated blood from mixing with deoxygenated blood as mammals and birds have high energy needs because they constantly require energy to maintain their body temperature.
(c)
(i) Three chambered heart.
(ii) Four chambered heart.(iii) Two chambered heart.
(d) The fish has a two chambered heart. Oxygenation of the blood takes place in the gills. The oxygenated blood from the gills is supplied to the body parts of the fish where oxygen is utilized and carbon dioxide enters into it making it deoxygenated. The deoxygenated blood returns to the heart to be pumped into gills again.

Question 54:
(a) What is lymphatic system ? What are its functions ?
(b) What is blood pressure ? What are the two factors used to express the blood pressure of a person ?
(c) Name the main nitrogenous waste in the human blood. How is it removed from the blood ?
Solution :
(a) Lymphatic system: A system of tiny tubes called lymph vessels (lymphatics) and lymph nodes (lymph glands) in the human body which transports the liquid called lymph from the body tissues to the blood circulatory system is called lymphatic system. Functions of lymphatic system:
(i) It takes part in the nutritive process of the body.
(ii) It protects the body by killing the germs drained out of the body tissues with the help of lymphocytes contained in the lymph nodes, by making antibodies.
(iii) It helps in removing the waste products like fragments of dead cells etc.
(b) Blood pressure: The pressure at which the blood is pumped around the body by the heart is called blood pressure. The two factors which expresses the blood pressure a person are systolic pressure and diastolic pressure.
(c) Urea is the main nitrogenous waste in human blood. It is removed from the body in the form of urine through the kidneys.

Question 55:
(a) Name the various organs of the human excretory system.
(b) Draw a neat labelled diagram of the human excretory system.
(c) What is the function of excretory system in humans ?
Solution :
(a) The excretory system of human beings consists of the following main organs: two kidneys, two ureters, bladder and urethra.

The human excretory system ( or urinary system) 

(c) The excretory system removes the poisonous waste substances from the body in the form of urine and maintains ionic balance called osmoregulation.

Question 56:
(a) Describe the mechanism of urine formation in human excretory system. Draw a labelled diagram to illustrate your answer.
(b) Where is urine carried through ureters ?
(c) What is urethra ?
Solution :
(a) Urine formation: The dirty blood containing waste like urea enters the glomerulus which filters the blood. During filtration, the substance like glucose, amino acids, salts, water, urea etc present in the blood pass into Bowman’s capsule and then enter the tubule of nephron. When the filtrate containing useful substances as well as the waste substances passes through the tubule, the useful substances like glucose, amino acids, most salts and water are reabsorbed into the blood through blood capillaries surrounding the tubule. Only the waste substances like urea, some unwanted salts and excess water remains behind in the tubule. This yellowish liquid is called urine.

Diagram to show the working of human excretory system

(b) Urinary bladder.
(c) Urethra is a tube which passes out the urine from the body collected in the urinary bladder.

Question 57:
(a) What is meant by dialysis ? What type of patients are put on dialysis ?
(b) Explain the principle of dialysis with the help of a labelled diagram.
Solution :
(a) Dialysis: The procedure used for cleaning the blood of a person by separating the urea from it is called dialysis. The patients with kidney failure are put on dialysis. (b) Principle of Dialysis: The blood from an artery in the patients arm is made to flow into the dialyser of a dialysis machine made of long tubes of selective permeable membrane (like cellulose) which are coiled in a tank containing dialysing Solution. The dialysing Solution contains water, glucose and salts in similar concentrations to those in normal blood. As the patient’s blood passes through the dialysing Solution most of the waste like urea present in it pass through the selectively permeable cellulose tubes into the dialysing Solution. The clean blood is pumped back into a vein of the patients arm.

The principle of the kidney dialysis machine

Question 58:
(a) Why is transport of materials necessary in an organism (plant or animal) ?
(b) What is the need of special tissues or organs for transport of substances in plants and animals ?
(c) How are water and minerals transported in plants ?
(d) How is food transported in plants ?
Solution :
(a) Transport in organisms (plants and animals) is necessary as it absorbs all essential substances and transports them to all parts so that they reach each and every cell of the body.
(b) Special tissues and organs are needed for the transport of substances in plants and animals because these tissues and organs can pick up the essential substances like food, oxygen, water, etc at one end of their body and carry them to all other parts.
(c) Water and minerals are transported to various parts of the plant by xylem tissues called xylem vessels and tracheids. Plants take in water from the soil through the roots. The water containing minerals called cell sap is carried by the xylem vessels to all the parts of the body. The roots have root hairs to absorb water and minerals from the soil by diffusion and then pass from cell to cell by osmosis through epidermis, root cortex, endodermis and then reach the root xylem. The water enters the root xylem into the stem xylem and then reaches the leaves from the petioles.

Diagram to show how water  (and dissolved minerals ) are 

transported from the soil up to the leaf of a plant

(d) Transportation of food in plants: The transport of food from the leaves to other parts of the plant is called translocation. Phloem tissue transports the food from the leaves to the other parts of the plant. The movement of food in phloem takes place by utilising energy. The sugar made in the leaves is loaded into the sieve tubes of phloem by using ATP. Water enters the sieve tube containing sugar which causes high pressure and pushes the food to all the parts of the plant having low pressure. This is how the food is transported according to the needs of the plant.