Lakhmir Singh & Manjit Kaur Solutions: Life Processes - 4

Page No - 74

Question 39:
(a) How many types of blood vessels are there in the human body ? Name them.
(b) Why does the heart need valves ?
Solution :
(a) There are three types of blood vessels in the human body - arteries, veins and capillaries.
(b) The heart needs valves to prevent the backflow of blood so that blood flows only in one direction through the chambers and into the major vessels. Valves ensure efficient, unidirectional circulation and help maintain proper blood pressure within the heart.

Question 40:
A dialysis machine contains long tubes coiled in a tank containing dialysing solution :
(i) Of what substance are the tubes made ?
(ii) What does the dialysing solution contain ?
(iii) Name the main waste which passes into the dialysing solution.
Solution :
(i) The tubes are made of a selectively permeable membrane material such as cellulose.
(ii) The dialysing solution contains water, glucose and salts in concentrations similar to those in normal blood so that useful substances are not lost from the blood.
(iii) The main waste that passes into the dialysing solution is urea.

Question 41:
State the differences between artery, vein and capillary.
Solution :

Question 42:
(a) What are the upper parts of the heart called ?
(b) What are the lower parts of the heart called ?
(c) What is the name of blood vessels which connect arteries to veins ?
(d)
(i) Which side of the heart pumps blood into the lungs ? .
(ii) Which side of the heart pumps blood into entire body (except the lungs) ?
Solution :
(a) Atria (singular: atrium).
(b) Ventricles.
(c) Capillaries.
(d)
(i) Right side of the heart pumps deoxygenated blood into the lungs.
(ii) Left side of the heart pumps oxygenated blood into the entire body (except the lungs).

Question 43:
(a) What are the methods used by plants to get rid of their waste products ?
(b) How are waste products excreted in Amoeba ?
Solution :
(a) The various methods used by plants to get rid of their waste products are:
(i) Gaseous wastes such as oxygen and carbon dioxide are released through stomata in leaves and lenticels in stems.
(ii) Solid and liquid wastes may be removed when parts of the plant are shed, for example by falling leaves, peeling bark or fallen fruits.
(iii) Some plants secrete wastes in the form of gums and resins.
(iv) Certain wastes are released into the soil from the roots.
(b) Excretion in Amoeba: Carbon dioxide diffuses out across the cell membrane. Excess water and nitrogenous wastes are expelled using the contractile vacuole, which collects and pumps out these wastes.

Question 44:
(a) What is lymph ? State two major functions of lymph.
(b) What is meant by saying that the blood pressure of a person is 120/80 ?
Solution :
(a) Lymph is a pale yellow fluid that circulates through the lymphatic vessels. It flows from body tissues towards the heart. Major functions of lymph are:
(i) It aids nutrition by carrying absorbed fats and some dissolved substances from tissues to the blood.
(ii) It helps protect the body against infection: lymph nodes contain lymphocytes that destroy germs and produce antibodies.
(iii) It helps remove waste materials such as fragments of dead cells from tissues.
(b) A blood pressure reading of 120/80 mm Hg means the systolic pressure (maximum pressure when the heart contracts) is 120 mm Hg, and the diastolic pressure (minimum pressure when the heart relaxes) is 80 mm Hg.

Question 45:
What is hypertension ? Why is it caused ? What harm can it do ?
Solution :
High blood pressure is called hypertension. It is commonly caused by persistent constriction of small arteries, blockage of arteries, excess salt intake, obesity, stress or other health conditions, all of which increase resistance to blood flow. Prolonged or very high blood pressure can damage blood vessels, cause the rupture of an artery, and lead to internal bleeding. It also raises the risk of heart disease, stroke and kidney damage.

Question 46:
What are the various components of blood ? State their functions.
Solution :
The main components of blood and their functions are:
(i) Plasma: The liquid part of blood that carries dissolved substances such as proteins, digested food, hormones and salts from one part of the body to another.
(ii) Red blood corpuscles (RBCs): Carry oxygen from the lungs to body cells and transport a small amount of carbon dioxide back to the lungs; they contain haemoglobin which binds oxygen.
(iii) White blood corpuscles (WBCs): Defend the body against infections by destroying germs and producing antibodies.
(iv) Platelets: Small cell fragments that help in blood clotting to prevent excessive loss of blood after injury.

Question 47:
With which human organ systems (or human systems) are the following associated ?
(i) vena cava (ii) glomerulus (in') alveoli (iv) villi
Solution :
(i) Vena cava - Circulatory system.
(ii) Glomerulus - Excretory system.
(iii) Alveoli - Respiratory system.
(iv) Villi - Digestive system.

Question 48:
What is meant by 'systolic pressure' and 'diastolic pressure' ? What are their normal values ?
Solution :
Systolic pressure is the maximum pressure in the arteries when the heart contracts and pushes blood into the aorta. Diastolic pressure is the minimum pressure in the arteries when the heart relaxes between two beats. The normal values in a healthy adult are about 120 mm Hg (systolic) and 80 mm Hg (diastolic).

Question 49:
(a) What is meant by 'heart beat' ? What is the usual heart beat rate at rest ?
(b) What change occurs in heart beats if a person runs for a while ? Why ?
Solution :
(a) Heart beat: One complete contraction and relaxation of the heart is called a heart beat. The usual resting heart rate for an adult is about 72 beats per minute.
(b) When a person runs, the heart rate increases (the heart beats faster) because muscles need more oxygen and nutrients and produce more carbon dioxide. Faster heart beats increase blood flow to deliver oxygen and remove wastes more quickly.

Question 50:
(a) What is blood ? Why is it red ?
State the functions of blood in our body.
Name a circulatory fluid in the human body other than blood.
Solution :
(a) Blood is a red-coloured fluid that circulates throughout the body. It is red because red blood cells contain the pigment haemoglobin, which gives blood its red colour.
(b) Functions of blood:
(i) Carries oxygen from the lungs to body cells.
(ii) Carries carbon dioxide from body cells to the lungs for removal.
(iii) Transports digested food from the small intestine to all parts of the body.
(iv) Transports wastes such as urea from the liver to the kidneys for excretion as urine.
(v) Helps protect the body against disease by transporting white blood cells and antibodies.
(c) Another circulatory fluid in the human body is lymph.

Question 51:
(a) What is meant by human circulatory system ? Name the organs of the circulatory system in humans.
Draw a diagram of the human heart and label its parts.
What is meant by the terms 'single circulation' and 'double circulation' ?
Solution :
(a) The human circulatory system is the system responsible for the transport of materials (such as gases, nutrients and wastes) throughout the body. The main organs of the human circulatory system are the heart, arteries, veins and capillaries.
(b)

(c) Single circulation is a pattern where blood passes through the heart only once during each complete circuit of the body. Double circulation is where the blood passes through the heart twice during one complete circuit - once to get oxygenated in the lungs and once to deliver oxygen to the body.

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 heart chambers are relaxed, oxygenated blood from the lungs enters the left atrium through the pulmonary vein.
(ii) When the left atrium contracts, this oxygenated blood flows through the valve V1 into the left ventricle.
(iii) When the left ventricle contracts, blood is pumped into the aorta, the main artery, and is carried to body organs through branches called arterioles and capillaries.
(iv) In the body tissues, oxygen and digested food leave the blood and pass into cells. Cells release carbon dioxide and other wastes into the blood. The now deoxygenated blood collects into veins and is carried back to the heart by the vena cava, entering the right atrium.
(v) When the right atrium contracts, the deoxygenated blood passes through valve V2 into the right ventricle.
(vi) When the right ventricle contracts, blood is pumped into the pulmonary artery and sent to the lungs where it releases carbon dioxide and receives fresh oxygen. The oxygenated blood then returns to the left atrium by the pulmonary vein and the cycle repeats 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) Separation of oxygenated and deoxygenated blood is necessary in mammals and birds because these animals have high energy demands and require an efficient supply of oxygen to body cells; keeping the two blood types separate ensures tissues receive fully oxygenated blood.
(c)
(i) Amphibian - Three-chambered heart.
(ii) Mammal - Four-chambered heart.
(iii) Fish - Two-chambered heart.
(d) In fish, the heart has two chambers (one atrium and one ventricle). Blood is pumped from the heart to the gills where it becomes oxygenated. From the gills, oxygenated blood flows to the body to supply tissues and becomes deoxygenated; it then returns to the heart to be pumped to the gills again. This system is an example of single circulation.

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 network of vessels (lymphatics) and lymph nodes that transport the fluid called lymph from body tissues into the blood circulatory system. Functions of the lymphatic system:
(i) It helps in the transport of absorbed fats and contributes to nutrition.
(ii) It protects the body by trapping and destroying germs; lymph nodes contain lymphocytes that produce antibodies.
(iii) It helps remove waste materials such as fragments of dead cells from tissues.
(b) Blood pressure is the pressure at which the heart pumps blood around the body. The two factors used to express blood pressure are systolic pressure (pressure during heart contraction) and diastolic pressure (pressure during heart relaxation).
(c) Urea is the main nitrogenous waste in human blood. It is removed by the kidneys and excreted from the body as urine.

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 main organs of the human excretory (urinary) system are two kidneys, two ureters, the urinary bladder and the urethra.

The human excretory system (or urinary system)

(c) The excretory system removes poisonous waste substances from the blood and body, mainly in the form of urine, and helps to maintain the ionic and water balance of the body (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: Blood containing wastes such as urea enters the kidney and is filtered in the glomerulus. Filtration allows water, salts, glucose, amino acids and urea to pass into Bowman's capsule. This filtered fluid (the filtrate) then moves through the nephron tubule. Useful substances such as most glucose, amino acids, selected salts and much of the water are reabsorbed back into the blood through capillaries surrounding the tubule. The remaining fluid, containing urea, some unwanted salts and excess water, becomes urine. The urine is collected in the renal pelvis and passes down the ureter.

Diagram to show the working of human excretory system

(b) Urine is carried through the ureters to the urinary bladder where it is stored temporarily.
(c) The urethra is the tube through which urine is passed out of the body from 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 is a medical procedure that cleans a patient's blood by removing waste substances such as urea when the kidneys are not functioning properly. Patients with kidney failure are put on dialysis.
(b) Principle of dialysis: Blood from an artery in the patient's arm is passed through a dialysis machine containing long coiled tubes made of a selectively permeable membrane (for example, cellulose). These tubes are immersed in a dialysing solution that has concentrations of glucose and salts similar to normal blood. As the patient's blood flows inside the tubes, small waste molecules such as urea pass through the membrane into the dialysing solution, while larger useful molecules remain in the blood. The cleaned blood is then returned to a vein in the patient's 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 is necessary because essential substances (water, oxygen, nutrients) must reach every cell and waste products must be removed from them.
(b) Special tissues and organs are needed because they are adapted to pick up substances at one location and carry them efficiently to all other parts of the organism, ensuring every cell gets what it needs.
(c) Water and mineral transport: Water and dissolved minerals are taken up by root hair cells from the soil and move inward through root tissues to the root xylem. Xylem vessels and tracheids carry water and minerals upward from the roots to the stem and leaves. This movement is driven by transpiration pull, root pressure and capillary action.
(d) Transport of food (translocation): Food produced in the leaves (mainly as sugars) is loaded into the sieve tubes of the phloem. Water enters these tubes by osmosis, creating pressure that pushes the sap (sugar solution) towards parts of the plant that need or store food. This movement requires metabolic energy and is regulated according to the plant's needs.