Class 10 NCERT Solutions Life Processes - NCERT Solutions prepared for CBSE students by the best teachers in Delhi.
Question 1: Why is diffusion insufficient to meet the oxygen requirements of multi-cellular organisms like humans?
Answer: 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.
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 life processes is a fundamental criterion that can be 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 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.
Question 5: What are the differences between autotrophic nutrition and heterotrophic nutrition?
Answer: Autotrophic nutrition Heterotrophic nutrition
(i) Food is synthesised from simple inorganic raw materials such as CO2and water.
(i) Food is obtained directly or indirectly from autotrophs. This food is broken down with the help of enzymes.
(ii) Presence of green pigment (chlorophyll) is necessary.
(ii) No pigment is required in this type of nutrition.
(iii)Food is generally prepared during day time.
(iii)Food can be prepared at all times.
(iv)All green plants and some bacteria havethis type of nutrition.
(iv)All animals and fungi have this type of nutrition.
Question 6: 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 7: What is the role of the acid in our stomach?
Answer: The hydrochloric acid present in our stomach dissolves bits of food and creates an acidic medium. In this acidic medium, enzyme pepsinogen is converted to pepsin, which is a proteindigesting enzyme.
Question 8: 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 9: 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 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 and every cell of the body.
Question 10: What advantage over an aquatic organism does a terrestrial organism have with regard to obtaining oxygen for respiration?
Answer: Terrestrial organisms take up oxygen from the atmosphere whereas aquatic animals need to utilize oxygen present in the water. Air contains more O2 as compared to water. Since the content of O2 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.
Question 11: 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 a three carbon molecule 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.
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