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| Life process - Class X - CBSE Classes by saurabh |
LIFE PROCESS - PREVIOUS YEAR QUESTIONS FROM CBSE EXAMS
Also read: money and credit previous year questions.
Very short type
Q1. Mention the raw materials required for photosynthesis. (Board Term I, 2016)
Answer:
Raw materials required for photosynthesis are carbon dioxide (CO2), water, light and chloroplast.
Q2. State the location and function of gastric glands. (Board Term I, 2014)
Answer:Gastrifc glands are present in the wall of the stomach. They secrete gastric juices containing mucus, protein digesting enzymes pepsin, rennin and hydrochloric acid (HCl).
Q3.Name the glands present in the wall of the stomach that release secretions for digestion of food. Write the three components of secretion that are released by these glands. (Board Term I, 2014)
Answer:
Stomach’s muscular wall contains gastric glands. These glands secrete gastric juices which contain dilute hydrochloric acid, mucus and two protein digesting enzymes rennin and pepsin.
Q4.What is the role of saliva in the digestion of food ? (CBSE Delhi 2008, CCE 2014, 2016)
Answer:
Saliva moistens the ingested food with mucus, sterilises it with lysozyme and partially digests starch part of food into sugar with the help of salivary amylase or ptyalin.
Q5. Name the process in plants where water is lost as water vapour. (CBSE A.I. 2010)
Answer:
Transpiration
Q6. Rings of cartilage are present in trachea. Why ? (CCE 2016)
Answer:
To prevent the collapse of air passage after expiration.
Q7.Name the component of blood that helps in the formation of blood clot in the event of a cut.
(CBSE Foreign 2010)
Answer:
Blood platelets which release thromboplastin on rupturing.
Q8. State one difference between autotrophic and heterotrophic modes of nutrition.
(CBSE A.I. 2010, CCE 2012)
Answer:
In autotrophic nutrition, the food is self manufactured while it is obtained ready-made from outside in heterotrophic nutrition.
Q9.Name the green dot like structures in some cells observed by a student when a leaf peel was viewed under a microscope. What is this green colour due to? [CBSE 2010]
Answer:
The green dot like structures in some cells observed by a student when a leaf peel was viewed under a microscope are chloroplasts. The green colour is due to the presence of green pigment, chlorophyll.
Q10. In the experiment “Light is essential for photosynthesis” Why does the uncovered part of the leaf turn blue black after putting iodine solution? [CBSE 2010]
Answer:
Starch is produce in the uncovered part of the leaf which turns blue black in presence of iodine solution.
Q11. Why do aquatic animal’s breath faster than the terrestrial animals? [CBSE 2009]
Answer:
Because the dissolved oxygen is fairly low in water compared to the amount of oxygen in the air.
Q12. When a sports man runs, he gets muscle cramps. Why? [CBSE 2016]
Answer:
During running the sportsman require large amount of energy instantly. In order to release more energy, Pyruvate is converted into lactic acid in the absence of oxygen. Accumulation of lactic acid in the muscle causes cramps.
Q13. What advantages over an aquatic animal does a terrestrial organism have with regard to obtaining oxygen for respiration? [CBSE 2008]
Answer:
The amount of oxygen dissolved in water is very low, as compare to amount of oxygen in air. Thus, terrestrial organism has to make less efforts to obtain oxygen then an aquatic organism to obtain oxygen for respiration.
Q14. Name two ways in which glucose is oxidised to provide energy in various organism? [CBSE 2008]
Answer:
The two ways in which glucose is oxidised to provide energy in various organism are aerobic respiration pathway which uses oxygen to breakdown glucose completely into carbon dioxide and water and some use other pathways that do not involve oxygen which is called anaerobic respiration pathway.
Q15. What is the role of acid in our stomach ?
Answer:
HCl of gastric juice disinfects the food and acidifies it for proper functioning of proteolytic enzyme pepsin.
Short answer type
Q1. What is the function of trachea ? Why do the walls not collapse even when there is less air in it ?
(CCE 2010, 2012)
Answer:
Trachea is a tube that connects pharynx with lungs for carrying air to and from lungs. Trachea is lined by ciliated mucus secreting pseudostratified epithelium for trapping dust particles and microbes.
Trachea does not collapse in reduced air pressure due to support of C-shaped cartilaginous rings.
Q2.What is saliva? States its role in the digestion of food. [CBSE 2011]
Answer:
Saliva is a watery fluid secrete by the salivary gland in the mouth. In the mouth, Food get mixed up with saliva secrete by salivary gland. Saliva contain an enzyme Salivary amylase which breaks polysaccharide starch into disaccharide maltose(sugar).
Q3. State two differences between arteries and veins? [CBSE 2011]
Answer:
Arteries: They are vessels which carry blood away from the heart to various organ of the body.
Arteries have thick elastic walls; since the blood is under high pressure.
Veins: Vein collect the blood from the different organ and bring it back to the heart.
They don’t have thick wall, because the blood is no longer under pressure.
Q4. How is transportation of water in xylem tissue different from translocation of food in Phloem tissue? [CBSE 2009]
Answer:
Physical forces (like transpiration pull and root pressure) help in transportation of water ion Xylem while translocation of food help in Phloem is achieved by utilizing energy. No energy required for water transport in xylem, energy required for translocation of food in phloem.
Q5. Write one function each of the following components of the transport system in human being: (i) Blood vessels (ii) Blood platelets (iii) Lymph (iv) Heart [CBSE 2008]
Answer:
Function of the following components of the transport system in human being are as follow:
(i) Blood vessels: There are three types of blood vessels of different sizes involved in blood circulation viz. arteries, veins, and capillaries which are all connected to form a continuous closed system.
(ii) Blood Platelets: They help in coagulation of blood and are called thrombocytes.
(iii) Lymph: It carries digested and absorbed fat from intestine and drains excess fluid from extra cellular space back into the blood.
(iv) Heart: It is a pumping organ that receives blood from the veins and pumping it into the arteries.
Q6. Explain the process of nutrition in Amoeba. (CCE 2011, 2012)
Answer:
Amoeba ingests food particles with the help of its pseudopodia. The ingested food particle or phagosome fuses with lysosome to form food vacuole. The digested food passes out of the vacuole into cytoplasm. The undigested matter is thrown out.
Q7. Leaves of a healthy potted plant were coated with vaseline. Will this plant remain healthy for long ? Give reasons for your answer. (CCE 2011, 2015)
Answer:
The plant will not remain healthy for long. Vaseline covers the cuticle and blocks the stomata.
As a result
▪️It is unable to obtain oxygen from air for respiration,
▪️It is unable to perform photosynthesis as no carbon dioxide diffuses from air.
▪️In the absence of transpiration, the leaves get heated up and injured.
Q8. Name the cells that control the opening and closing of stomatal pore. Flow do they perform this function ?
(CCE 2016)
Answer:
Guard cells: Opening and closing of stomata is regulated by gain or loss of turgidity of their guard cells. During opening of stomata, guard cells withdraw K+ ions from surrounding epidermal cells, followed by absorption of water from them. As a result, guard cells swell up and become turgid. Their outer thin and elastic walls bend outwardly followed by outward movement of thicker inner walls. The latter creates a pore in between the two guard cells.
During closure movement of stomata, guard cells send out K+ ions. Water also passes out. Guard cells become flaccid. Their inner thick walls come to touch each other. The stomatal pore gets closed.
Q9. “The breathing cycle is rhythmic whereas exchange of gases is a continue process”. Justify the statement. (ii) What happen if conducting tubes of circulatory system develops a leak? State in brief how could this be avoided? (iii) How opening and closing stomata take place? [CBSE 2011]
Answer:
(i) Even through the breathing cycle is rhythmic the lungs always contain a residual volume of air so that absorption of oxygen and release of carbon dioxide becomes continuous.
(ii) The circulatory system will become inefficient if it develops a leak this could be avoided by maintaining a normal blood pressure.
(iii) When water flows into the guard cells the guard cell swell and the stomata pore open up. The guard cell shrink when water moves out and the stomata pore closes.
Q10. (a) What do you mean by double circulation of blood ? (CBSE A.I. 2007, Delhi 2008 C,CCE 2011, 2012)
(b) Why is it necessary ? (CBSE Delhi 2008 C)
Answer:
(a) Double circulation is the passage of same blood twice through heart, first from right side to lungs and back to left side for passage to rest of the body to be returned to right side. It consists of two components, pulmonary circulation (from heart to lungs and back) and systemic circulation (from heart to different parts of body and back). In pulmonary circulation deoxygenated blood is converted into oxygenated blood. In systemic circulation oxygenated blood is supplied to all parts of the body. It gets changed into deoxygenated form.
(b) Importance. Double circulation ensures supply of oxygenated blood to all body parts for efficient release of energy to ensure higher physical activity and thermoregulation of body. It also provides for direct passage of all deoxygenated blood to lungs for oxygenation.
Long Answer type
Q1. (a) List two differences between ‘holozoic nutrition’ and ‘saprophytic nutrition. Give two examples each of these two types of nutrition.
(b) State the roles of liver and pancreas.
(c) Name the organ which performs the following functions in humans :
Absorption of digested food
Absorption of water.
(d) Explain the statement, “Bile does not contain any enzyme but it is essential for digestion.”
(CBSE A.I. 2005, Delhi 2007, 2009)
Answer:
(a) Differences between Holozoic Nutrition and Saprophytic Nutrition
Holozoic Nutrition Saprophytic Nutrition
1. Type. It is ingestive type where solid food is taken in.
2. Digestion. It is internal.
Examples. Tiger, Cattle.
It is absorptive type of nutrition where simple soluble substances are taken in.
Digestion is external.
Examples. Rhizopus, Mushroom.
(b)
Role of Liver: Decomposition of haemoglobin, formation and secretion of bile for emulsification of fat. Formation of urea, heparin fibrinogen and prothrombin. Detoxification of chemicals and elimination of pathogens.
Role of Pancreas: Secretion of pancreatic juice having lipase, trypsin and amylase; secretion of hormones, insulin and glucagon.
(c)
Absorption of Digested Food. Ileum part of small intestine.
Absorption of Water. Large intestine.
(d) Role of Bile in Digestion.
Breaking of fat into fine globules or emulsification,
Neutralisation of acidity and making food alkaline for action of pancreatic and other enzymes.
Q2. (a) List three events that occur during the process of photosynthesis. State in brief the role of stomata in this process.
(b) Describe an experiment to show that sunlight is essential for photosynthesis.
(CBSE Delhi 2010, CCE 2010)
Answer:
(a) Three Events of Photosynthesis: Information is transmitted from one plant cell to another through plasmodesmata and hormones.
Role of Stomata in Photosynthesis. Inward diffusion of carbon dioxide and outword diffusion of oxygen.
(b) Sunlight is Essential for Photosynthesis: It is the source of energy for photosynthesis. Light is visible part of the electromagnetic radiations. It has a wavelength of 390-760 nm. Photosynthetically active radiations or PAR are 400-700 nm. Natural source of light is sun but artificial light can also provide energy to plants for their photosynthesis. Plants absorb light mostly in violet-blue and red parts of visible light. Violet-blue light carries more energy as compared to red light. Plants growing under shade of others receive mostly green and some violet light. They have lower rates of photosynthesis.
Light has two functions, photolysis of water and excitation of chlorophyll to emit electrons. Photolysis of water produces oxygen, protons and electrons. Electrons and protons (Hydrogen ions) help in producing ATP and NADPH2, popularly called assimilatory power.
Q3. (a) Name the enzyme present in saliva. Why is it important ?
(b) What is emulsification ?
(c) Name the substance that is oxidised in the body during respiration.
(d) Why are lungs divided into very small sac-like structures ? (CCE 2011)
Answer:
(a) Enzyme. Ptyalin or salivary amylase. It breaks down starch to form maltose sugar.
(b) Emulsification: Emulsification of fat is the conversion of large fat pieces into very fine fat globules which can be efficiently acted upon by lipase.
(c) Glucose
(d) To increase surface area for exchange of gases.
Q4. Explain how water and minerals are transported in plants. (CCE 2015)
Answer:
Water and minerals absorbed by the plant roots are passed into xylem as sap. Sap present in xylem is under tension or negative pressure as mesophyll and other cells of aerials parts lose water to the outside through transpiration.
Development of Negative Pressure. Loss of water by mesophyll and other cells of aerial parts in transpiration increases their suction pressure. They withdraw water from xylem channels. As there are billions of transpiring mesophyll cells withdrawing water from xylem channels, water present in xylem comes under negative pressure of 10-20 atmospheres. However, water column does not break due to
(a) Cohesive force amongst water molecules and
(b) Adhesion force between walls of xylem channels and water moecules.
Rise of Sap (Water and Minerals). Tension or negative pressure of water column results in upward pull just as cold-drink is sucked with the help of straw pipe. Since it develops due to transpiration, it is called transpiration pull. The mechanism of this ascent of sap was put forth by Dixon and Joly in 1894.
Q5. Explain why digestion of food is essential for all living beings. Mention the form in which energy derived from the food we eat is stored. (CCE 2015)
Answer:
(a) Food consists of complex components which cannot pass into body cells directly for nourishment. They are broken down into simpler absorbable form through the process of digestion. Digestion is intracellular in simple animals. It is intercellular inside a digestive tract in higher animals including humans. The digested materials are absorbed and transported by blood to all parts for picking up by individual cells for assimilation. The latter is then used for both release of energy and building of cellular components.
(b) Energy derived from food is stored as glycogen and fat.
Q6. (a) Explain the excretory system in human beings. (CCE 2011)
(b) List four strategies used by plants for excretion. (CCE 2011, 2016)
Answer:
(a) In human beings, the excretory system consists of a pair of kidneys, a pair of ureters, a urinary bladder and a urethra.
Kidneys are a pair of reddish brown bean-shaped structures that lie dorsally in the abdominal cavity. A renal artery and a renal vein occur on the concave hilus region of each kidney. About a million structural and functional units called nephrons occur in each kidney. Blood is filtered in the glomerular region of a nephron. Useful substances (e.g. glucose, amino acids, salts, water) are reabsorbed and urine passes into collecting ducts. Ureters are pulsatile drainage tubes that carry urine from the kidneys to the urinary bladder. Urinary bladder is a pear-shaped distensible sac that stores urine till its volume becomes 300-800 ml. Urethra is a fine tube that carries urine from urinary bladder to the outside.
(b) Excretion Strategies in Plants,
▪️Excess water is passed out through transpiration,
▪️Excess O2 formed during the day diffuses out of the leaves.
▪️Alkaloids, organic acids and tannins are the common secondary metabolites. Some of these are stored in the cell vacuoles of leaves which when old fall down,
Resins and gums alongwith other wastes are also deposited in old non-functional xylem.
Q7.(a) Explain in brief the mechanism of circulation of blood in the human body.
(b) “Lymph is another type of fluid involved in transportation”. Justify the statement by explaining the process.
(CCE 2011)
Answer:
(a) Deoxygenated blood is collected by superior vena cava from upper part of the body, by inferior vena cava from middle and lower parts of the body and coronary sinus from the walls of heart. All the three pour their blood into right auricle. Oxygenated blood is brought by pulmonary veins from the lungs. It is poured into left auricle. On being filled, the two auricles contract simultaneously and pass their bloods into ventricles, deoxygenated in right ventricle and oxygenated in left ventricle. The distended ventricles now undergo contraction or systole forcefully. Right ventricle passes blood to pulmonary arch which divides to form pulmonary arteries. Pulmonary arteries take the deoxygenated blood to lungs. Left ventricle passes blood to systemic aorta that supplies oxygenated blood to all parts of the body.
(b) Lymph is a fluid that is specialised to collect those materials from the tissues which cannot pass directly into blood, e.g., proteins, hormones, fats (from intestine). Lymph collects the same and pass them to blood in the region of subclavian veins. For passage of lymph, the lymphatic system has lymph capillaries, lymph vessels and lymph nodes.
Q8. (a) List the major steps involved in formation of urine and state in brief their functions.
(b) State how is the process of breathing brought about in our body. (CCE 2012, 2013)
Answer:
(a) Major Steps in Urine Formation,
Glomerular Filtration,
Ultrafiltration of blood passing through urine
Part which connects (i) and (ii).
Part from which urine is passed out glomerule produces a dilute filtrate having most of the small volume solutes of plasma. It passes into Bowman’s capsule and then renal tubule,
Formation of Urine. Useful solutes and a major part of water are reabsorbed while some waste products left in the blood are secreted into filtrate to form urine.
(b) Breathing In (Inhalation). Thoracic cavity enlarges due to
Straightening of diaphragm by contraction of phrenic muscles
Upward and outward expansion of ribcage due to contraction of external intercostal muscles. Enlargement of thoracic cavity causes expansion of lungs and decrease in air pressure in them. Outside air rushes into lungs to equalise pressure.
Q9. (a) The upward movement of water normally requires a pump in our houses, but in tall trees water rises up without any external support. Explain the mechanism.
Answer:
(a) Water and minerals absorbed by the plant roots are passed into xylem as sap. Sap present in xylem is under tension or negative pressure as mesophyll and other cells of aerials parts lose water to the outside through transpiration.
Development of Negative Pressure. Loss of water by mesophyll and other cells of aerial parts in transpiration increases their suction pressure. They withdraw water from xylem channels. As there are billions of transpiring mesophyll cells withdrawing water from xylem channels, water present in xylem comes under negative pressure of 10-20 atmospheres. However, water column does not break due to
Cohesive force amongst water molecules and
Adhesion force between walls of xylem channels and water moecules.
Rise of Sap (Water and Minerals). Tension or negative pressure of water column results in upward pull just as cold-drink is sucked with the help of straw pipe. Since it develops due to transpiration, it is called transpiration pull. The mechanism of this ascent of sap was put forth by Dixon and Joly in 1894.
Q10. (a) Write the name of different components of transports system in human beings and state their function in brief. (b) How is blood clot from, if a leak develops in the system of blood vessels? [CBSE 2017, 2018]
Answer:
(a) Arteries carry oxygenated blood from heart to various organs of the body. They are thick walled. Veins carry deoxygenated blood from various organs to the heart They are thin walled.
Blood: Oxygen is transported to the tissue of the body for the purpose of respiration. carbon dioxide is transported to the lungs by the blood plasma. The digested and the absorbed nutrient are transported to the tissue. Nitrogenous waste is transported to the kidney. The blood regulates the body temperature. It maintains the pH of the body tissue. It transported various hormone from one region to another and bring about the coordination. It maintains water balance to constant level. The lymphocytes produce antibodies against the invading antigens and protects from the diseases. Blood helps in rapid healing of wounds by forming a clot at the site of injury.
Heart: It is a pumping organ that receives blood from the veins and pumping it into the arteries.
(b) If there is a leak in the blood vessel due to injury then the blood platelets help plugs this leaks. The platelets make the clot by forming a mesh like structure over the leak in which other blood cells get entangled ultimately plugging the leak.
