CBSE Class 10 Science Life Processes VBQs Set 02

Question. Autotrophic organisms include
(a) bacteria and virus
(b) bacteria and fungi
(c) green plants and some bacteria
(d) green plants and all bacteria
Answer: (c) green plants and some bacteria

Question. A gland not associated with the alimentary canal is
(a) liver
(b) salivary glands
(c) pancreas
(d) adrenal
Answer: (d) adrenal

Question. Which of the following are chiefly digested in the stomach?
(a) Carbohydrates
(b) Proteins
(c) Lipids
(d) Fats
Answer: (b) Proteins

Question. The process in which loss of water takes place in the form of water vapour through stomata is called
(a) transportation
(b) transpiration
(c) guttation
(d) translocation
Answer: (b) transpiration

Question. Many processes happen in the bodies of living organisms. Those processes which involve the building up of complex molecules from simpler ones are called anabolism. Those which involve the breakdown of complex molecules into simpler ones are called catabolism. Which of the following life processes can be considered as an example of anabolism?
(a) Digestion
(b) Respiration
(c) Transpiration
(d) Photosynthesis
Answer: (d) Photosynthesis

Question. Read the following two statements and answer the question.
1. Gastroparesis is a disease in which the muscles of the stomach become paralysed and cannot contract or relax.
2. Foods high in fat can delay the process of digestion and the emptying of the stomach.
Which of the following food would be advised to a patient suffering from gastroparesis?
(a) Soups and juices only
(b) Soups and chicken salads only
(c) Fried chicken and fried rice
(d) Ice cream and milk only
Answer: (a) Soups and juices only

Question. Opening and closing of stomata is due to:
(a) High pressure of gases inside the cells.
(b) Movement of water in and out of the guard cells.
(c) Stimulus of light in the guard cells.
(d) Diffusion of \( CO_2 \) in and out of the guard cells.
Answer: (b) Movement of water in and out of the guard cells.

Question. An incomplete equation for the digestion of starch using saliva is shown as: Saliva + Starch (in test tube) \( \to \) What will be the likely outcome of this?
(a) Saliva will convert starch into complex fat molecules.
(b) Saliva will convert starch into complex sugar molecules.
(c) Saliva will breakdown starch into simple sugar molecules.
(d) Saliva will breakdown starch into simple protein molecules.
Answer: (c) Saliva contains an enzyme called salivary amylase that breaks down starch which is a complex molecule to give simple sugar.

Very Short Answer Type Questions

Question. Explain the process of nutrition in Amoeba.
Answer: The mode of nutrition in Amoeba is holozoic. It feeds on unicellular plant or animal. The various steps of nutrition are ingestion, digestion, assimilation and egestion. When Amoeba comes in contact with food particles, it sends out pseudopodia, which engulfs the prey by forming a food cup, which is known as ingestion. When the tips of the encircling pseudopodia touch each other, the food is encaptured into a bag called food vacuole. The food vacuole serves as a temporary stomach secreting digestive juice, this step is known as digestion. The digested food gets absorbed and diffuses into the cytoplasm and then assimilated. Egestion of undigested food takes place at any point on the surface of the body.

Question. What is saliva? State its role in the digestion of food.
Answer: Saliva is a watery fluid secreted by the salivary glands in the mouth. In the mouth, food gets mixed up with saliva secreted by salivary glands. Saliva contains an enzyme salivary amylase which breaks polysaccharide starch into disaccharide maltose (sugar).

Question. What is the role of HCl in protein digestion?
Answer: HCl activates pepsinogen into active pepsin, which is a protease.

Question. Why is the inner wall of alimentary canal not digested although the digestive enzyme can digest all the materials that make cells?
Answer: The inner wall of alimentary canal is not digested because it has the following protective mechanisms:
(i) The gastric mucin secreted by the gastric mucosa acts as buffer, which reduces high gastric acidity and prevents injury to the inner wall of the alimentary canal.
(ii) The enzymes are secreted only when food is present in the alimentary canal and they are in an inactive form.

Question. Where are salivary glands situated in man? What are their functions?
Answer: Salivary glands are situated in the mouth of man and contains starch-digestive enzymes. Salivary glands secrete saliva and the mucin in saliva helps to lubricate the food for swallowing.

Question. State two functions performed by bile juice.
Answer: Bile juice is secreted by the liver. (i) It contains bile pigments, bile salts that emulsifies fat to fatty acids. (ii) Bile juice also neutralizes the acidic food in the stomach and makes it alkaline so that it can react with the enzymes of pancreatic juice.

Question. Write any two functions of large intestine in man.
Answer: Functions of large intestine in man are: (i) It serves to store the unabsorbed food remnants temporarily. (ii) It concentrates the contents by absorbing water. (iii) The movements of colon help to void the faeces through anus.

Question. How would digestion of food be affected if the bile duct is completely blocked? Explain.
Answer: If the bile duct is completely blocked, bile juice will not reach the small intestine and the digestion of fats will be affected.

Question. How would it affect the digestion of proteins and carbohydrates in the duodenum of man if there is a blockage in the pancreatic duct? Explain.
Answer: If there is a blockage in the pancreatic duct, the pancreatic juice which contains enzymes for the digestion of carbohydrates and proteins will not reach the small intestine.

Question. What are enzymes? Name any one enzyme of our digestive system and write its function.
Answer: Enzymes are biological catalysts. Catalysts are proteins that increase the rate of chemical reactions without being used up. For example: Amylase catalyses the breakdown of starch into sugars in the mouth and small intestine.

Question. Patients whose gall bladder are removed are recommended to eat less oily food. Why?
Answer: Gall bladder stores bile which helps in emulsification of lipids. In the absence of stored bile, emulsification of fats will be negligible/ affected/ less and thus fat digestion will be slow. Hence there are such diet restrictions.

Question. There are various muscles present in the human digestive system known as sphincters. Two examples of those are given below: 1. pyloric sphincter - at the junction of stomach and small intestine 2. anal sphincter - at the anus. Give ONE most likely consequence of malfunctioning of each of these sphincters.
Answer: Pyloric sphincter: Food getting into small intestine too fast causing poor absorption/poor digestion.
Anal sphincter: Involuntary release of feces from the body.

Question. (a) What is peristaltic movement? (b) ‘Stomata remain closed in desert plants during daytime’. How do they do photosynthesis?
Answer: (a) The relaxation of gut muscles to move the partially digested food downwards throughout the alimentary canal is called peristaltic movement. (b) In desert plants, stomata open at night and take in carbon dioxide (\( CO_2 \)). Stomata remain closed during daytime to prevent the loss of water by transpiration. They take carbon dioxide during the night time and convert it into intermediate product of photosynthesis. During the day time in the presence of sunlight this intermediate compound is convert into the final product of photosynthesis.

Question. In each of the following situations what happens to the rate of photosynthesis? (a) Cloudy days (b) Stomata gets blocked due to dust.
Answer: (a) In cloudy days photosynthesis is reduced due to low light intensity. (b) When stomata gets blocked due to dust, photosynthesis decreases by reducing gaseous exchange.

Short Answer Type Questions

Question. (a) Explain the process of nutrition in Amoeba. (b) If you chew chapatti for long after some time it taste sweet? Why is this so?
Answer: (a) The various steps of nutrition are ingestion, digestion, assimilation and egestion. When Amoeba comes in contact with food particles, it sends out pseudopodia, which engulfs the prey by forming a food cup, which is known as ingestion. When the tips of the encircling pseudopodia touch each other, the food is encaptured into a bag called food vacuole. The food vacuole serves as a temporary stomach secreting digestive juice, this step is known as digestion. The digested food gets absorbed and diffuses into the cytoplasm and then assimilated. Egestion of undigested food takes place at any point on the surface of the body.
(b) Chapatti contains starch which is converted to simple sugar by the action of enzyme salivary amylase. The salivary glands help in chemical digestion by secreting enzyme.

Question. (a) 1 ml of dilute starch solution (1% starch solution) is taken in test tube and 1 ml of saliva is added to it. After keeping the mixture for an hour, few drops of iodine solution are added to the test tube. Is there any change in the colour of the test tube? What does this tell you about the action of saliva on starch? (b) How would digestion of food be affected if the bile duct is completely blocked? Explain.
Answer: (a) There is no change in colour when iodine solution is added to the test tube. Saliva had broken down starch into simple sugar which does not react with iodine solution to produce any colour. (b) If the bile duct is completely blocked, bile juice will not reach the small intestine and the digestion of fats will be affected.

Question. (a) Where are salivary glands situated in man? What are their functions? (b) Name the first digestive organ that is associated with the breakdown of proteins in humans. What are its three releases?
Answer: (a) Salivary glands are situated in the mouth of man and contains starch-digestive enzymes. Salivary glands secrete saliva which helps to lubricate the food for swallowing and helps in digestion of starch. (b) The first digestive organ in humans is the stomach. It releases are enzymes, HCl and mucus.

Question. (a) Write the functions of large intestine in man. (b) What is dental caries? What are its adverse effect?
Answer: (a) The walls of large intestine absorbs water and electrolytes from the undigested food and forms and stores faeces. (b) It is the tooth decay which involves destruction of the enamel layer of the tooth by acids produced by the action of bacteria on sugar. If dental caries is not treated, it can spread to the dentine and pulp of the tooth, causing inflammation and infection of the tooth.

Question. (a) What are enzymes? Name any one enzyme of our digestive system and write its function. (b) Explain the cause of cramps after excessive physical exercise.
Answer: (a) Enzymes are biological catalysts, which increase the rate of chemical reactions without being used up. For example: Salivary amylase catalyses the breakdown of starch into sugars in the mouth and small intestine. (b) During excessive physical exercise, most of our energy in our muscles is produced by aerobic respiration. Anaerobic respiration in muscles provide only some extra energy which is needed under excessive physical exercise. The anaerobic respiration breakdown glucose into lactic acid. This lactic acid accumulates in the muscle. This accumulation of lactic acid in this muscles cause muscle cramps.

Question. In human alimentary canal, name the site of complete digestion of various components of food. Explain the process of digestion.
Answer: In small intestine, complete digestion of various components of food take place. The process of digestion of food in mouth, stomach and small intestine in human body are as follows:
Mouth: Digestion of food begins in the mouth. Saliva present in mouth contains a digestive enzyme, called salivary amylase, which breaks down starch into sugar.
Stomach: Stomach stores and mixes the food received from the oesophagus with gastric juices. The main components of gastric juice are hydrochloric acid, mucus and pepsin.

Question. State the role of the following in human digestive system: (a) Digestive enzymes (b) Hydrochloric acid (c) Villi
Answer: (a) Digestive enzymes digest the food we eat. (b) Hydrochloric acid creates an acidic medium to facilitate the action of enzyme pepsin. (c) Villi increases the surface area inside the small intestine to facilitate absorption of food.

Question. (a) How does Paramecium obtain its food? (b) List the role of each of the following in our digestive system: (i) Hydrochloric acid (ii) Trypsin (iii) Muscular walls of stomach (iv) Salivary amylase
Answer: (a) In Paramecium the cell has a definite shape and food is taken in at a specific spot. Food is moved to this spot by the movement of cilia which cover the entire surface of the cell. (b) (i) The hydrochloric acid creates an acidic medium in stomach which facilitates the action of protein digesting enzyme pepsin. (ii) Trypsin enzyme is secreted by pancreas for digesting proteins. (iii) Muscular walls of stomach contract periodically and help in the churning and mixing of food with the digestive enzymes and HCl acid. (iv) Salivary amylase enzyme is present in saliva and it breaks down starch which is a complex sugar to give simple sugar.

Question. Leaves of a healthy potted plant were coated with vaseline. Will this plant remain healthy for long? Give reasons for your answer.
Answer: The leaves of a healthy plant coated with vaseline would not stay healthy because vaseline coating will block the stomata. In the plant, there will be no intake of carbon dioxide from the surrounding to carry out the process of photosynthesis because the pores of stomata are blocked by the vaseline.

Long Answer Type Questions

Question. (a) Name the process and explain the type of nutrition found in green plants. List the raw materials required for this process. Give chemical equation for the mentioned process. (b) Write three events that occur during this process.
Answer: (a) – Photosynthesis is the process. – Green plants show autotrophic nutrition. – The raw materials required for photosynthesis are carbon dioxide and water and energy in the form of sunlight. – The equation is as follows: \( 6CO_2 + 12H_2O \xrightarrow[Sunlight]{Chlorophyll} C_6H_{12}O_6 + 6O_2 + 6H_2O \).
(b) The three events in photosynthesis are (i) Absorption of light energy by chlorophyll. (ii) Conversion of light energy to chemical energy and spliting of water molecules into hydrogen and oxygen. (iii) Reduction of carbon dioxide to carbohydrates.

Question. Define heterotrophic nutrition. What are the various types of heterotrophic nutrition? Give examples of each.
Answer: Heterotrophic Nutrition: The type of nutrition in which organisms derive their food (nutrients) from other living organisms. In heterotrophic nutrition, the energy is derived from the intake and digestion of the organic substances, normally of plant or animal tissue. Heterotrophic mode of nutrition are of different types:
(i) Saprotrophic Nutrition: It refers to the mode of nutrition in which organisms obtain nutrients from the dead and decaying organic matter, e.g., fungi, yeast and bacteria are called saprophytes.
(ii) Parasitic Nutrition: It refers to the mode of obtaining food synthesised by others. The organism which obtains food is called the ‘parasite’ and the organism from which food is absorbed is called the ‘host’. This nutrition is observed in fungi, bacteria, a few plants like Cuscuta and some animals like Plasmodium and roundworm.
(iii) Holozoic Nutrition: It refers to the mode of nutrition in which the complex organic matter in the form of solid food is ingested, digested and then absorbed into the cells and utilised, e.g., Amoeba, frog, human beings.

Practice Questions

Question. Amoeba shows the following kind of nutrition–
(a) Autotrophic
(b) Holozoic
(c) Saprotrophic
(d) Parasitic
Answer: (b) Holozoic

Question. Which of the following organisms have parasitic mode of nutrition?
(a) Penicillium
(b) Plasmodium
(c) Paramecium
(d) Rhizobium
Answer: (b) Plasmodium

Question. Why leaves become yellow in the absence of light?
Answer: In the absence of light, chlorophyll degrades and cannot be synthesized, leading to the loss of green color and revealing yellow pigments like xanthophylls and carotenes.

Question. Bile juice does not contain any digestive enzymes, yet it is essential for digestion, why so? Explain.
Answer: Bile juice contains bile salts which break down large fat globules into smaller ones (emulsification), increasing the efficiency of pancreatic lipase. It also creates an alkaline medium in the small intestine for pancreatic enzymes to function.

Question. Name two proteases in pancreatic juice. What are their specific roles?
Answer: Trypsin and Chymotrypsin. Their role is to break down proteins and peptones into smaller peptides.

Question. (a) Which enzyme initiates the digestion of proteins? Name the other enzyme produced by the same gland. (b) How would the digestion of proteins and carbohydrates be affected if the pancreatic duct is completely blocked?
Answer: (a) Pepsin initiates protein digestion in the stomach. The other enzyme produced by gastric glands is gastric lipase (in small amounts) and mucus/HCl are also released. (b) Digestion of proteins and carbohydrates will be severely impaired as enzymes like trypsin, chymotrypsin, and pancreatic amylase will not reach the duodenum.

Question. Name the main organs of the human digestive system in the order they participate in the process of digestion. Describe how digestion of carbohydrates and proteins take place in our body.
Answer: The order is Mouth, Oesophagus, Stomach, Small Intestine, Large Intestine, Anus. Carbohydrates are digested by salivary amylase in the mouth and pancreatic amylase in the small intestine into glucose. Proteins are digested by pepsin in the stomach and trypsin in the small intestine into amino acids.