CBSE Class 10 Science Life processes Sure Shot Questions Set 04

This page lists 25 sure shot questions with answers for CBSE Class 10 Science Chapter 5, Life Processes, chosen from the questions that are asked most often in school and board examinations. They cover nutrition and digestion, photosynthesis experiments, breathing and respiration, double circulation, transport in plants and the formation of urine, and the answers are written in clear steps with tables where comparison is needed.

Short Answer Sure Shot Questions

Question 1. Why do herbivores have longer small intestine than carnivores?
Answer:
Herbivores eat plant food such as grass, which has a lot of cellulose. Cellulose takes a long time to digest, so the herbivore’s small intestine is long and gives enough time and space for its complete digestion.
Carnivores eat meat, which is easy and quick to digest, so they have a shorter small intestine.
In simple words: Cellulose needs a long time to digest, so grass-eaters have a longer intestine.

Teacher's Note:
1. Name cellulose as the reason.
2. Contrast the two diets.

Question 2. Why is diffusion insufficient to meet the oxygen requirements of multicellular organisms like humans?
Answer:
A unicellular organism has its whole cell in direct contact with the surroundings, so oxygen reaches it easily by diffusion.
In a multicellular organism like a human being, a large number of cells, tissues and organs lie deep inside and are not in direct contact with the environment. Diffusion alone is too slow over such long distances to supply every cell quickly.
So humans need special respiratory organs (lungs) and a transport system (blood with haemoglobin).
In simple words: Deep cells cannot get oxygen fast enough by diffusion alone.

Teacher's Note:
1. Contrast unicellular and multicellular organisms.
2. Mention the lungs and blood as the solution.

Question 3. Why is it necessary to separate oxygenated and de-oxygenated blood in mammals and birds?
Answer:
Mammals and birds are warm-blooded animals. They need a lot of energy to keep their body temperature constant.
The separation of oxygenated and deoxygenated blood (a four-chambered heart) allows a highly efficient supply of oxygen to the body cells, so that more energy is released by respiration.
In simple words: Separate blood streams give the body more oxygen and so more energy to stay warm.

Teacher's Note:
1. Link warm-blooded with high energy needs.
2. Mention the four-chambered heart.

Question 4. What is the role of saliva in the digestion of food?
Answer:
Saliva is secreted by the salivary glands.
It moistens the food and helps in forming a bolus that can be swallowed easily.
It contains the enzyme salivary amylase (ptyalin), which breaks down starch into sugar (maltose) in the mouth: Starch → maltose.
In simple words: Saliva wets the food and begins the digestion of starch.

Teacher's Note:
1. Give both the lubricating and the enzyme role.
2. Write the enzyme and its food.

Question 5. What is the role of the acid in our stomach?
Answer:
The acid in the stomach is hydrochloric acid (HCl) from the gastric glands.
(i) It makes the medium acidic so that the enzyme pepsin can act on proteins.
(ii) It kills the bacteria that enter the body with the food.
In simple words: Stomach acid helps pepsin to work and kills germs.

Teacher's Note:
1. Give two roles.
2. Mucus protects the stomach wall from this acid.

Question 6. How are fats digested in our bodies? Where does this process take place?
Answer:
Fat digestion takes place in the small intestine.
Fats are present there as large globules. Bile juice from the liver breaks them into small globules (emulsification), which gives a larger surface for enzymes.
The enzyme lipase from the pancreas (and the intestinal juice) then converts them into fatty acids and glycerol.
In simple words: Bile breaks fat into tiny drops, and lipase changes them into fatty acids and glycerol in the small intestine.

Teacher's Note:
1. Name the organ, bile, emulsification and lipase.
2. Write the final products.

Question 7. What are the different ways in which glucose is oxidised to provide energy in various organisms?
Answer:
The first step is the same in all organisms: in the cytoplasm, glucose (6-carbon) is broken down into pyruvate (3-carbon) with the release of a little energy.
Then pyruvate is broken down in different ways:
(i) In the presence of oxygen (aerobic): in the mitochondria, pyruvate → carbon dioxide + water + energy (a large amount).
(ii) In the absence of oxygen in yeast (fermentation): pyruvate → ethanol + carbon dioxide + energy.
(iii) In the absence of oxygen in our muscles: pyruvate → lactic acid + energy.
In simple words: Glucose first becomes pyruvate; then it is broken down with oxygen, or without oxygen into alcohol or lactic acid.

Teacher's Note:
1. Start with the common first step in the cytoplasm.
2. Give the three paths and their products.

Question 8. How are the lungs designed in human beings to maximise the area for exchange of gases?
Answer:
The air passage divides into smaller and smaller tubes which end in millions of balloon-like alveoli.
The alveoli give a very large surface area, their walls are very thin, and each is surrounded by a rich network of blood capillaries. So oxygen from the alveolar air diffuses into the blood and carbon dioxide diffuses from the blood into the alveoli.
The lungs always keep some air (residual volume) so that there is enough time for oxygen to be absorbed and for carbon dioxide to be released.
In simple words: Millions of thin-walled alveoli with blood capillaries give a huge surface for gas exchange.

Teacher's Note:
1. Say large surface, thin walls and blood supply.
2. Name the alveoli.

Comparison and Mechanism Sure Shot Questions

Teacher's Note:
1. Write three rows in a table.
2. Add one example of each.

Teacher's Note:
1. Compare oxygen, products, energy and place.
2. Name yeast as an example.

Teacher's Note:
1. Write at least three points with what, direction and energy.
2. Name the cells of each tissue.

Teacher's Note:
1. Compare structure first, then function.
2. Name glomerulus and Bowman’s capsule.

Question 13. How do the guard cells regulate opening and closing of stomatal pores?
Answer:
Each stomatal pore is surrounded by two bean-shaped guard cells.
Opening: when water flows into the guard cells by osmosis, they swell up and become turgid. The thin outer walls bulge outward and pull the thick inner walls apart, so the pore opens.
Closing: when water leaves the guard cells, they shrink and become flaccid, and the pore closes.
So the pore opens and closes with the turgor of the guard cells. This controls the exchange of gases and the loss of water vapour.
In simple words: Guard cells fill with water to open the pore and lose water to close it.

Teacher's Note:
1. Use the words turgid and flaccid.
2. Mention both gas exchange and water loss.

Long Answer Sure Shot Questions

Question 14. Define the term transpiration. Design an experiment to demonstrate this process.
Answer:
Transpiration is the loss of water in the form of vapour from the aerial parts of a plant, mainly through the stomata of the leaves.
Experiment: Take a potted plant and cover the soil and the pot with a polythene sheet so that water cannot evaporate from the soil. Enclose the leafy shoot in a large transparent polythene bag and tie it. Keep the plant in the sunlight for about two hours.
Observation: water droplets collect on the inner wall of the bag.
Conclusion: the water vapour came from the leaves, which shows transpiration.
In simple words: A bag tied over the leaves collects the water vapour that the leaves give out.

Teacher's Note:
1. Cover the soil so that only the plant is the source of water.
2. State observation and conclusion.

Question 15. (i) What is translocation? Why is it essential for plants?
(ii) Where do the substances in plants reach as a result of translocation?
Answer:
(i) The transport of food (soluble products of photosynthesis) from the leaves to the other parts of the plant is called translocation. It takes place through the phloem and uses energy. It is essential because the food made in the leaves must reach all other parts for their growth, development and energy; without it these parts would starve.
(ii) The substances reach all the other tissues of the plant, such as the roots, stem, growing buds, flowers, fruits, seeds and storage organs.
In simple words: Translocation delivers the leaf-made food to every part of the plant.

Teacher's Note:
1. Name the phloem and mention energy.
2. Say why it is essential.

Question 16. What are the methods used by plants to get rid of excretory products?
Answer:
(1) Oxygen from photosynthesis and carbon dioxide from respiration are removed through the stomata.
(2) Excess water is lost from the leaves by transpiration.
(3) Some wastes are passed into the soil through the roots.
(4) Many wastes are stored in the vacuoles of cells.
(5) Some wastes are lost as gums, resins and latex.
(6) Some wastes are stored in leaves that fall off, or in the bark and old xylem (wood) that is shed from time to time.
In simple words: Plants release wastes through stomata and transpiration, and store or shed the rest.

Teacher's Note:
1. Give at least four methods.
2. Use the words stomata, vacuole and falling leaves.

Question 17. Explain the nutrition process in amoeba.
Answer:
Amoeba follows holozoic nutrition, which has these steps:
(1) Ingestion: it surrounds the food particle with its finger-like temporary projections, the pseudopodia, and engulfs it into a food vacuole.
(2) Digestion: enzymes are secreted into the food vacuole and break the complex food into simple, soluble substances.
(3) Absorption and assimilation: the digested food diffuses into the cytoplasm and is used for energy, growth and repair.
(4) Egestion: the undigested residue is thrown out through the cell surface at any point.
In simple words: Amoeba wraps food in a vacuole, digests it there and throws out the rest.

Teacher's Note:
1. Name the steps in order.
2. Use pseudopodia and food vacuole.

Question 18. Describe double circulation in human beings? Why is it necessary?
Answer:
In humans the blood passes through the heart twice in one complete round of the body, so this is called double circulation.
Pulmonary circulation: deoxygenated blood from the body enters the right atrium (through the vena cava), goes to the right ventricle and is pumped by the pulmonary artery to the lungs. Oxygenated blood returns by the pulmonary veins to the left atrium.
Systemic circulation: oxygenated blood goes from the left atrium to the left ventricle, and is pumped through the aorta to all parts of the body.
Why necessary: it keeps oxygenated and deoxygenated blood separate. This gives an efficient supply of oxygen and the high energy needed by warm-blooded animals to keep their body temperature constant.
In simple words: Blood goes to the lungs and back to the heart, and then to the body, so the heart pumps it twice.

Teacher's Note:
1. Describe the two loops in order.
2. Give the reason for the separation.

Question 19. What are the components of the transport system in human beings? What are the functions of these components?
Answer:
The transport system of human beings has these components:
(1) Heart: the pumping organ that pumps blood to all parts of the body.
(2) Blood: a fluid made of plasma and blood cells; it carries oxygen and nutrients to the cells and carries carbon dioxide and wastes away.
(3) Blood vessels: arteries carry blood from the heart to the organs, veins bring blood back to the heart, and capillaries are thin vessels that join arteries and veins and where exchange with the cells occurs.
(4) Lymph: carries digested fat from the intestine and drains excess fluid from the spaces between cells back into the blood.
In simple words: Heart, blood, vessels and lymph move materials around the body.

Teacher's Note:
1. Name the four parts and a function for each.
2. Name the three kinds of vessels.

Question 20. Describe the process of urine formation in kidneys.
Answer:
Urine is formed in the nephrons in three steps:
(1) Ultrafiltration: blood flows under high pressure through the glomerulus. Its liquid part, containing wastes and useful substances, filters into the cup-shaped Bowman’s capsule.
(2) Selective reabsorption: as the filtrate flows along the renal tubule, glucose, amino acids, salts and most of the water are reabsorbed into the blood.
(3) Tubular secretion: some more wastes, such as extra salts and drugs, pass from the blood into the tubule.
The urine from the nephrons is collected by the collecting ducts, flows through the ureter to the urinary bladder, is stored there, and is passed out through the urethra.
In simple words: Blood is filtered, the useful substances are taken back, and the rest goes out as urine.

Teacher's Note:
1. Write the three steps in order.
2. Trace the path to the urethra.

Question 21. Explain the mechanism of breathing.
Answer:
Breathing has two steps.
Inhalation (breathing in): the intercostal muscles contract and the ribs move upward and outward. The diaphragm contracts, flattens and moves down. The chest (thoracic) cavity becomes larger, the air pressure inside the lungs falls, and air from outside rushes in and fills the alveoli.
Exhalation (breathing out): the intercostal muscles relax so the ribs move down and inward, and the diaphragm relaxes and moves up to its dome shape. The chest cavity becomes smaller and the air is pushed out of the lungs.
In simple words: Ribs and diaphragm change the size of the chest, and this makes the air move in and out.

Teacher's Note:
1. Name ribs, intercostal muscles and the diaphragm.
2. Write what happens to the chest cavity in each step.

Question 22. How do autotrophs obtain food? Explain the process with the help of a balanced chemical equation.
Answer:
Autotrophs, such as green plants, make their own food by photosynthesis.
The raw materials are carbon dioxide, taken from the air through the stomata, and water with minerals, absorbed from the soil by the roots. The leaf pigment chlorophyll absorbs sunlight.
Equation: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ (in the presence of sunlight and chlorophyll).
The carbohydrate (glucose) formed is changed into starch and stored, and oxygen is released as a by-product.
In simple words: Plants use sunlight to turn carbon dioxide and water into glucose and oxygen.

Teacher's Note:
1. Show the equation with the condition written over the arrow.
2. Name the raw materials and how they enter.

Question 23. Describe an experiment to prove that CO₂ is necessary for photosynthesis.
Answer:
Procedure:
(1) Take two healthy potted plants of nearly the same size and keep them in a dark room for three days (to destarch them).
(2) Place each plant on a separate glass plate. Keep a watch glass containing potassium hydroxide (KOH) near one plant. KOH absorbs carbon dioxide.
(3) Cover both plants with separate bell jars and seal the bottoms with Vaseline so that the set-up is air-tight.
(4) Keep both in sunlight for about two hours. Then pluck a leaf from each plant, boil it in water and then in alcohol to remove the chlorophyll, and test it with iodine solution.
Observation: the leaf from the plant without KOH turns blue-black (starch present). The leaf from the plant with KOH does not.
Conclusion: carbon dioxide is necessary for photosynthesis.
In simple words: Without carbon dioxide (absorbed by KOH) the leaf makes no starch.

Teacher's Note:
1. Mention destarching and an air-tight set-up.
2. State observation and conclusion separately.

Question 24. (i) List three events that occur during the process of photosynthesis. State in brief the role of stomata in this process.
(ii) Describe an experiment to show that sunlight is essential for photosynthesis.
Answer:
(i) The three events are: (a) absorption of light energy by chlorophyll; (b) conversion of light energy into chemical energy and splitting of water molecules into hydrogen and oxygen; (c) reduction of carbon dioxide to carbohydrates.
Role of stomata: carbon dioxide enters the leaf, and oxygen leaves it, through the stomata (gaseous exchange).
(ii) Experiment: cover a part of a leaf of a destarched potted plant with black paper and keep the plant in the sun for about six hours. Pluck this leaf, boil it in water and then in alcohol to remove the chlorophyll, and add iodine solution.
Observation: the covered part does not turn blue-black, while the uncovered part turns blue-black. So starch is formed only where light fell, and sunlight is necessary for photosynthesis.
In simple words: The part of the leaf kept in the dark makes no starch.

Teacher's Note:
1. Write the three events in order.
2. Mention the iodine test and the colour change.

Question 25. Explain the digestion process in human beings?
Answer:
Digestion takes place in different parts of the alimentary canal:
(1) Mouth: saliva contains salivary amylase, which breaks starch into maltose.
(2) Oesophagus: no digestion takes place; the food (bolus) moves to the stomach by peristalsis.
(3) Stomach: the gastric juice has hydrochloric acid, the enzyme pepsin and mucus. Pepsin starts the digestion of proteins into peptones.
(4) Small intestine: it receives bile from the liver and pancreatic juice from the pancreas, and secretes intestinal juice. Bile emulsifies fats; trypsin acts on proteins, lipase on fats and amylase on starch. Digestion is completed here: carbohydrates into glucose, proteins into amino acids, and fats into fatty acids and glycerol.
(5) Large intestine: no digestion; water is absorbed and the undigested waste is passed out through the anus.
In simple words: Starch starts in the mouth, protein in the stomach, and everything finishes in the small intestine.

Teacher's Note:
1. Go through the canal from mouth to anus.
2. Name the enzyme of each part.