NCERT Solutions for Class 10 Science Chapter 5 Life Processes latest edition includes answers of intext & exercise questions. All these NCERT solutions are prepared by expert teachers with detailed explanations of every important topic. It is important for the students to go through these NCERT solutions to get knowledge of the type of question asked on the Life Processes chapter.
NCERT Solutions for Class 10 Science Chapter 5 Intext Questions
Page Number: 81
Question 1: Why is diffusion insufficient to meet the oxygen requirements of multicellular organisms like humans?
Answer: In multi-cellular organisms, all the cells may not be in direct contact with the surrounding environment. Thus, simple diffusion will not meet the requirements of all the cells.
Question 2: What criteria do we use to decide whether something is alive?
Answer: Any visible movement such as walking, breathing, or growing is generally used to decide whether something is alive or not. However, a living organism can also have movements, which are not visible to the naked eye. Therefore, the presence of molecular movement inside the organisms used to decide whether something is alive or not.
Question 3: What are outside raw materials used for by an organism?
Answer: An organism uses outside raw materials mostly in the form of food (Since life on earth depends on carbon-based molecules, most of these food sources are also carbon-based) and oxygen. The raw materials required by an organism can be quite varied depending on the complexity of the organism and its environment.
Question 4: What processes would you consider essential for maintaining life?
Answer: Life processes such as nutrition, respiration, transportation, excretion, etc. are essential for maintaining life.
Page Number: 87
Question 1: What are the differences between autotrophic nutrition and heterotrophic nutrition?
Answer:
| Autotrophic nutrition | Heterotrophic nutrition | ||
| 1. | Food is synthesized from simple inorganic raw materials such as CO2 and water. | 1. | Food is obtained directly or indirectly from autotrophs. This food is broken down with the help of enzymes. |
| 2. | Presence of green pigment (chlorophyll) is necessary. | 2. | No pigment is required in this type of nutrition. |
| 3. | Food is generally prepared during day time. | 3. | Food can be prepared at all times. |
| 4. | All green plants and some bacteria have this type of nutrition. | 4. | All animals and fungi have this type of nutrition. |
Question 2: Where do plants get each of the raw materials required for photosynthesis?
Answer: The following raw materials are required for photosynthesis:
- The raw material CO2 enters from the atmosphere through stomata.
- Water is absorbed from the soil by the plant roots.
- Sunlight, an important component to manufacture food, is absorbed by the chlorophyll and other green parts of the plants.
Question 3: What is the role of the acid in our stomach?
Answer: Role of the acid (HCl) in our stomach
- Kills germs present in the food.
- Makes the food acidic, so that pepsin can digest protein.
OR
The acid in our stomach, primarily hydrochloric acid, plays several important roles:
- Digestion: It helps in the digestion of food, especially proteins, by breaking them down into smaller, more easily absorbed molecules.
- Killing Germs: The acidic environment kills most of the bacteria and other germs that enter the stomach with food, helping to prevent infections.
- Activating Enzymes: The acid activates an enzyme called pepsin, which further aids in protein digestion.
- Absorption of Nutrients: It helps in the absorption of certain essential nutrients, like Vitamin B12.
Overall, stomach acid is crucial for proper digestion and protecting the body from harmful pathogens.
Question 4: What is the function of digestive enzymes?
Answer: Digestive enzymes such as amylase, lipase, pepsin, trypsin, etc. help in the breaking down of complex food particles into simple ones. These simple particles can be easily absorbed by the blood and thus transported to all the cells of the body.
Question 5: How is the small intestine designed to absorb digested food?
Answer: The small intestine has millions of tiny finger-like projections called villi. These villi increase the surface area for food absorption. Within these villi, many blood vessels are present that absorb the digested food and carry it to the bloodstream. From the bloodstream, the absorbed food is delivered to each and every cell of the body.
Page Number: 91
Question 1: What advantage over an aquatic organism does a terrestrial organism have with regard to obtaining oxygen for respiration?
Answer: Since the amount of dissolved oxygen is fairly low compared to the amount of oxygen in the air, the rate of breathing in aquatic organisms is much faster than that seen in terrestrial organisms. Therefore, unlike aquatic animals, terrestrial animals do not have to show various adaptations for better gaseous exchange.
Question 2: What are the different ways in which glucose is oxidized to provide energy in various organisms?
Answer: Glucose is first broken down in the cell cytoplasm into three carbon molecule called pyruvate. Pyruvate is further broken down in the following ways to provide energy:
Question 3: How is oxygen and carbon dioxide transported in human beings?
Answer: Haemoglobin transports oxygen molecule to all the body cells for cellular respiration. The haemoglobin pigment present in the blood gets attached to O2 molecules that are obtained from breathing. It thus forms oxyhaemoglobin and the blood becomes oxygenated. This oxygenated blood is then distributed to all the body cells by the heart. After giving away O2 to the body cells, blood takes CO2 which is the end product of cellular respiration. Now the blood becomes deoxygenated. Since haemoglobin pigment has less affinity for CO2, CO2 is mainly transported in the dissolved form. This de-oxygenated blood gives CO2 to lung alveoli and takes O2 in return.
Question 4: How are the lungs designed in human beings to maximise the area for exchange of gases?
Answer: The exchange of gases takes place between the blood capillaries that surround the alveoli and the gases present in the alveoli. Thus, alveoli are the site for the exchange of gases. The lungs get filled up with air during the process of inhalation as ribs are lifted up and the diaphragm is flattened. The air that is rushed inside the lungs fills the numerous alveoli present in the lungs. Each lung contains 300-350 million alveoli. These numerous alveoli increase the surface area for gaseous exchange making the process of respiration more efficient.
Page Number: 96
Question 1: What are the components of the transport system in human beings? What are the functions of these components?
Answer: The main components of the transport system in human beings are the heart, blood, and blood vessels.
Heart pumps oxygenated blood throughout the body. It receives deoxygenated blood from the various body parts and sends this impure blood to the lungs for oxygenation.
Blood is a fluid connective tissue, it helps in the transport of oxygen, nutrients, CO2, and nitrogenous wastes.
Blood vessels (arteries, veins, and capillaries) carry blood either away from the heart to various organs or from various organs back to the heart.
Question 2: Why is it necessary to separate oxygenated and deoxygenated blood in mammals and birds?
Answer: Warm-blooded animals such as birds and mammals maintain a constant body temperature by cooling themselves when they are in a hotter environment and by warming their bodies when they are in a cooler environment. Hence, these animals require more oxygen (O2) for more cellular respiration so that they can produce more energy to maintain their body temperature. Thus, it is necessary for them to separate oxygenated and de-oxygenated blood, so that their circulatory system is more efficient and can maintain their constant body temperature.
Question 3: What are the components of the transport system in highly organized plants?
Answer: In highly organized plants, there are two different types of conducting tissues − xylem and phloem.
Xylem: Responsible for transporting water and dissolved minerals from the roots to the rest of the plant. It’s like the plant’s water pipeline.
Phloem: Carries sugars and other organic nutrients made in the leaves to different parts of the plant. It’s like the plant’s food distribution network.
These two systems work together to ensure that water, nutrients, and food are efficiently transported throughout the plant.
Question 4: How are water and minerals transported in plants?
Answer: The components of xylem tissue (tracheids and vessels) of roots, stems and leaves are interconnected to form a continuous system of water-conducting channels that reaches all parts of the plant. Transpiration creates a suction pressure, as a result of which water is forced into the xylem cells of the roots. Then there is a steady movement of water from the root xylem to all the plant parts through the interconnected water-conducting channels.
Question 5: How is food transported in plants?
Answer: Phloem transports food materials from the leaves to different parts of the plant body. The transportation of food in phloem is achieved by utilizing energy from ATP. As a result of this, the osmotic pressure in the tissue increases causing water to move into it. This pressure moves the material in the phloem to the tissues which have less pressure. This is helpful in moving materials according to the needs of the plant. For example, the food material, such as sucrose, is transported into the phloem tissue using ATP energy.
Page Number: 98
Question 1: Describe the structure and functioning of nephrons.
Answer: Nephrons are the basic filtering units of kidneys. Each kidney possesses a large number of nephrons, approximately 1-1.5 million. The main components of the nephron are glomerulus, Bowman’s capsule, and a long renal tubule.
Functioning of a nephron:
- capillaries associated with glomerulus.
- The water and solute are transferred to the nephron at Bowman’s capsule. In the proximal tubule, some substances such as amino acids, glucose, and salts are selectively reabsorbed and unwanted molecules are added in the urine.
- The filtrate then moves down into the loop of Henle, where more water is absorbed.
- From here, the filtrate moves upwards into the distal tubule and finally to the collecting duct. Collecting duct collects urine from many nephrons.
- The urine formed in each kidney enters a long tube called ureter. From ureter, it gets transported to the urinary bladder and then into the urethra.
Question 2: What are the methods used by plants to get rid of excretory products?
Answer: Plants use completely different strategies for excretion than those animals. They can get rid of excess water by transpiration. For other wastes, plants use the fact that many of their tissues consist of dead cells, and that they can even lose some parts such as leaves. Many plant waste products are stored in cellular vacuoles. Waste products may be stored in leaves that fall off. Other waste products are stored as resins and gums, especially in old xylem. Plants also excrete some waste substances into the soil around them.
Question 3: How is the amount of urine produced regulated?
Answer: The amount of urine produced is regulated mainly by the hormone ADH (Antidiuretic Hormone) which controls how much water the kidneys reabsorb. More ADH means less urine is produced, and less ADH means more urine. Other factors like fluid intake, salt levels, and kidney function also play a role.
NCERT Solutions for Class 10 Science Chapter 5 Exercise Questions
Question 1: The kidneys in human beings are a part of the system for
(a) nutrition.
(b) respiration.
(c) excretion.
(d) transportation.
Answer: (c) excretion.
Question 2: The xylem in plants are responsible for
(a) transport of water.
(b) transport of food.
(c) Transport of amino acids.
(d) Transport oxygen.
Answer: (a) transport of water.
Question 3: The autotrophic mode of nutrition requires
(a) carbon dioxide and water
(b) chlorophyll.
(c) sunlight.
(d) all of the above.
Answer: (c) sunlight.
Question 4: The breakdown of pyruvate to give carbon dioxide, water and energy takes place in
(a) cytoplasm.
(b) mitochondria.
(c) chloroplast.
(d) nucleus.
Answer: (b) mitochondria.
Question 5: How are fats digested in our bodies? Where does this process take place?
Answer: Fats are digested primarily in the small intestine where they get the secretions in the form of bile juice and pancreatic juice respectively from the liver and the pancreas. This process involves:
- Emulsification: Bile, produced by the liver and stored in the gallbladder, breaks down large fat globules into smaller ones, making them easier to digest.
- Enzymatic Digestion: Enzymes from the pancreas, particularly lipase, break these smaller fat globules into fatty acids and glycerol.
This digestion allows fats to be absorbed into the body for use as energy or storage.
Question 6: What is the role of saliva in the digestion of food?
Answer: Saliva is secreted by the salivary glands, located under the tongue. It makes the food soft for easy swallowing. It contains a digestive enzyme called salivary amylase, which breaks down starch into sugar.
Question 7: What are the necessary conditions for autotrophic nutrition and what are its byproducts?
Answer: Autotrophic nutrition takes place through the process of photosynthesis. Carbon dioxide, water, chlorophyll pigment, and sunlight are the necessary conditions required for autotrophic nutrition. Carbohydrates (food) and O2 are the byproducts of photosynthesis.
Question 8: What are the differences between aerobic and anaerobic respiration? Name some organisms that use the anaerobic mode of respiration.
Answer: Difference between Aerobic respiration and Anaerobic respiration:
| Aerobic respiration | Anaerobic respiration |
| It occurs in the presence of O2. | It occurs in the absence of O2 |
| It involves the exchange of gases between the organism and the outside environment. | The exchange of gases is absent. |
| It occurs in the cytoplasm and mitochondria. | It occurs only in the cytoplasm. |
| It always releases CO2 and H2O. | It produces alcohol and CO2. |
| It yields a large amount of energy. | The energy released is very low. |
Question 9: How are the alveoli designed to maximize the exchange of gases?
Answer: The alveoli are the small balloon-like structures present in the lungs. The walls of the alveoli consist of an extensive network of blood vessels. Each lung contains 300−350 million alveoli, making it a total of approximately 700 million in both lungs. The alveolar surface when spread out covers about 80 m2 area. This large surface area makes the gaseous exchange more efficient.
Question 10: What would be the consequences of a deficiency of haemoglobin in our bodies?
Answer: Haemoglobin is the respiratory pigment that transports oxygen to the body cells for cellular respiration. A deficiency of haemoglobin in the body can lead to anemia. This condition can cause symptoms like tiredness, weakness, shortness of breath, and paleness because hemoglobin is essential for carrying oxygen in the blood. Without enough of it, the body’s organs and tissues don’t get enough oxygen to work effectively.
Question 11: Describe double circulation in human beings. Why is it necessary?
Answer: Because both oxygen and carbon dioxide have to be transported by the blood, the heart has different chambers to prevent the oxygen-rich blood from mixing with the blood containing carbon dioxide. The human heart is divided into four chambers − the right atrium, the right ventricle, the left atrium and the left ventricle.
Oxygen-rich blood from the lungs comes to the thin-walled upper chamber of the heart on the left, the left atrium. The left atrium relaxes when it is collecting this blood. It then contracts, while the next chamber, the left ventricle, expands, so that the blood is transferred to it. When the muscular left ventricle contracts in its turn, the blood is pumped out to the body.
De-oxygenated blood comes from the body to the upper chamber on the right, the right atrium, as it expands. As the right atrium contracts, the corresponding lower chamber, the right ventricle, dilates. This transfers blood to the right ventricle, which in turn pumps it to the lungs for oxygenation. During this process blood goes twice through the heart. That’s why it is known as double circulation.
Double Circulation is necessary: The separation of oxygenated and de-oxygenated blood allows a more efficient supply of oxygen to the body cells. This efficient system of oxygen supply is very useful in warm-blooded animals such as human beings. As we know, warm blooded animals have to maintain a constant body temperature by cooling themselves when they are in a hotter environment and by warming their bodies when they are in a cooler environment. Hence, they require more O2 for more respiration so that they can produce more energy to maintain their body temperature.
Thus, the circulatory system of humans is more efficient because of the double circulatory heart.
Question 12: What are the differences between the transport of materials in xylem and phloem?
Answer: Difference between Xylem and Phloem:
| Xylem | Phloem |
| Xylem tissue helps in the transport of water and minerals. | Phloem tissue helps in the transport of food. |
| Water is transported upwards from roots to all other plant parts. | Food is transported in both upward and downward directions. |
| Transportation in xylem occurs with the help of simple physical forces such as transpiration pull. | Transport of food in phloem requires energy in the form of ATP. |
Question 13: Compare the functioning of alveoli in the lungs and nephrons in the kidneys with respect to their structure and functioning.
Answer:
| Aspect | Alveoli in Lungs | Nephrons in Kidneys |
| Structure | Tiny air sacs with thin walls, surrounded by blood capillaries. | Tiny filtering units composed of a glomerulus and a tubule, surrounded by capillaries. |
| Function | Exchange of gases – oxygen is absorbed into the blood, and carbon dioxide is released. | Filtration of blood – removal of waste and excess substances, reabsorption of needed materials. |
| Method of Transport | Diffusion based on oxygen and carbon dioxide concentration gradients. | Filtration under pressure, followed by selective reabsorption and secretion. |
| End Products | Tiny filtering units are composed of a glomerulus and a tubule, surrounded by capillaries. | Urine, which carries waste and excess substances out of the body. |
| Blood Supply | Supplied by the pulmonary arteries and veins. | Supplied by renal arteries and veins. |
| Regulation | Regulated by breathing rate and depth, responding to oxygen and carbon dioxide levels in the blood. | Regulated by hormones and kidney function, responding to body’s water and electrolyte needs. |