NCERT Class 10: Science-Intext Solutions

Chapter 06-Life Process-Intext Solutions

NCERT Book – Page Number- 95
Q.1. Why is diffusion insufficient to meet the oxygen requirements of multicellular organisms like humans?
Ans. Multicellular organisms such as humans possess complex body designs. They have specialised cells and tissues for performing various necessary functions of the body such as intake of food and oxygen. Unlike unicellular organisms, multicellular cells are not in direct contact with the outside environment. Therefore, diffusion cannot meet their oxygen requirements.
Q.2. What criteria do we use to decide whether something is alive?
Ans. 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 movement, which is not visible to the naked eye. Therefore, the presence of life processes is a fundamental criterion that can be used to decide whether something is alive or not.
Q.3. What are outside raw materials used for an organism?
Ans. An organism uses outside raw materials mostly in the form of food and oxygen. The raw materials required by an organism can be quite varied depending on the complexity of the organism and its environment.
Q.4. What processes would you consider essential for maintaining life?
Ans. Life processes such as nutrition, respiration, transportation, exertion, etc. control, coordination are essential for maintaining life.
NCERT Book – Page Number- 101

Q.1. What are the differences between autotrophic nutrition and heterotrophic nutrition?

Q.2. Where do plants get each of the raw materials required for potosynthesis?
Ans. The following raw materials are required for photosynthesis :
• The raw materials like $ CO_{2}$ enters from the atmosphere through stomata.
• Water is absorbed from the soil by the roots of plants.
• Sunlight, an important component to manufacture food, is trapped by the chlorophyll found in green parts of the plants.
Q.3. What is the role of the acid in our stomach?
Ans. The hydrochloric acid that is secreted in our stomach dissolves bits of food and creates an acidic medium. In this acidic medium, pepsinogen is converted to anzymepepsin which is a protein digesting enzyme.
Q.4. What is the function of digestive enzymes?
Ans. Digestive enzymes such as amylase, lipase, pepsin, trypsin, etc. help in the breaking down of complex food particles into simpler ones. These simple particles can be easily absorbed by the blood and thus transported to all the cells of the body.
Q.5. How is the small intestine designed to absorb digested food?
Ans. The small intestine has millions of tiny finger-like projections called villi. These villi increase the surface area for more efficient food absorption. Within these villi, many blood vessels are present that absorb the digested food and carry it to the blood stream. From the blood stream, the absorbed food is delivered to each cell of the body.

NCERT Book – Page Number- 105

Q.1. What advantage over an aquatic organism does a terrestrial organism have with regard to obtaining oxygen for respiration?
Ans. Terrestrial organisms take up oxygen from the atmosphere whereas aquatic animals need to utilise oxygen present in the water. Air contains more $ O_{2}$ as compared to water. Since the content of $ O_{2}$ in air is high, the terrestrial animals do not have to breathe faster to get more oxygen. Therefore, unlike aquatic animals, terrestrial animals do not have to show various adaptations for better gaseous exchange.
Q.2. What are the different ways in which glucose is oxidised to provide energy in various organisms?
Ans. Glucose is first broken down in the cell cytoplasm into a three carbon molecules called pyruvate. Pyruvate is further broken down by different ways to provide energy. The breakdown of glucose by different pathways can be illustrated as follows:

In yeast and human muscle cells, the breakdown of pyruvate occurs in the absence of oxygen
whereas in mitochondria, the breakdown of pyruvate occurs in the presence of oxygen.
Q.3. How is oxygen and carbon dioxide transported in human beings?
Ans. Haemoglobin transports oxygen molecules to all the body cells for cellular respiration. The haemoglobin pigment present in the blood gets attached to four $ O_{2}$ 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 $ O_{2}$ to the body cells, blood takes away $CO_{2}$ which is the end product of cellular respiration. Now the blood becomes deoxygenated. Since haemoglobin pigment has less affinity for $CO_{2}$, $CO_{2}$ is mainly transported in the dissolved form. This deoxygenated blood gives $CO_{2}$ to lung alveoli and takes $ O_{2}$ in return.

Q.4. How are the lungs designed in human beings to maximise the area for exchange of gases?
Ans. The exchange of gases takes place between the blood of the capillaries that surround the alveoli and the gases present in the alveoli. Thus, alveolus is the site for exchange of gases. The lungs get filled up with air during the process of inhalation as ribs are lifted up and 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.

NCERT Book – Page Number- 110

Q.1. What are the components of the transport system in human beings? What are the functions of these components?
Ans. The main components of the transport system in human beings are the heart, blood, and blood vessels.
• The 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.
• Being a fluid connective tissue, blood helps in the transport of oxygen, nutrients, $CO_{2}$ and nitrogenous wastes.
• Arteries, veins and capillaries are the blood vessels. Arteries carry the blood away from the heart to various organs and veins carry the blood from various organs back to the heart. The capillaries deliver the pure blood to the cells and take the impure blood from them.
Q.2. Why is it necessary to separate oxygenated and deoxygenated blood in mammals and birds?
Ans. 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 $(O_{2})$ for more cellular respiration so that they can produce more energy to maintain their body temperature. That is why it is necessary for them to separate oxygenated and deoxygenated blood, so that their circulatory system becomes more efficient and maintains their constant body temperature.
Q.3. What are the components of the transport system in highly organised plants?
Ans. In highly organised plants, there are two different types of conducting tissues – xylem and phloem. Xylem tissues conduct water and minerals obtained from the soil (via roots) to the rest of the plant. Phloem transports food materials from the leaves to different parts of the plant body.

Q.4. How are water and minerals transported in plants?
Ans. 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 plants.

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.
Q.5. How is food transported in plants?
Ans. Phloem transports food materials from the leaves to different parts of the plant body. The transportation of food in phloem is achieved by utilising energy from ATP. As a result the osmotic pressure in the tissue increases causing water to move into it. This pressure moves the materials 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.

NCERT Book – Page Number- 112

Q.1. Describe the structure and functioning of nephrons.
Ans. Nephrons are the basic filtering units of kidneys. Each kidney possesses 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
• The blood enters the kidney through the renal artery, which branches into many 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. Each collecting duct collects urine from many nephrons.
• The urine formed in each kidney enters a long tube called ureter. Through ureters, it gets collected into the urinary bladder and then passes out through the urethra.
Q.2. What are the methods used by plants to get rid of excretory products?
Ans. Plants can get rid of excess of water by transpiration. Waste materials may be stored in the cell vacuoles or as gum and resin, especially in old xylem. It is also stored in the leaves that later fall off.
Q.3. How is the amount of urine produced regulated?
Ans. The amount of urine produced depends on the amount of excess water and dissolved wastes present in the body. Some other factors such as habitat of an organisms and hormone such as Antidiuretic hormone (ADH) also regulates the amount of urine produced.