10th Grade Science: Life Processes with Complimentary Ncert Solutions

• Solution:

  The inner lining of the small intestine undergoes a structural modification, forming villi, which are finger-like projections. These villi serve to increase the surface area for the absorption of digested food. Furthermore, they have a high vascularity, meaning they are well-supplied with blood vessels. Villi also contain lactease, which aids in the absorption of digested fats.

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• Solution:

  Aquatic creatures rely on the dissolved oxygen within water. However, due to the low solubility of oxygen in water, there is limited availability of oxygen for these organisms. Consequently, they must respire at a faster rate. Conversely, terrestrial animals obtain oxygen directly from the atmosphere, resulting in a comparatively slower respiratory rate.

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• Solution:

  The utilization of glucose for energy production is dependent on the presence of oxygen. When oxygen is available, glucose is aerobically broken down in mitochondria. However, in the absence of oxygen, glucose is broken down anaerobically in the cytoplasm, resulting in a smaller amount of energy.

  Aerobic Respiration refers to the complete oxidation of food in the presence of oxygen, leading to the formation of CO2, H2O, and the release of significant energy. On the other hand, Anaerobic Respiration involves the incomplete oxidation of food in the absence of oxygen. For instance, skeletal muscles respire anaerobically under intense exertion or during vigorous exercise to obtain additional energy. This process involves the partial breakdown of glucose, resulting in the production of CO2, ethyl alcohol, lactic acid, and energy.

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  Solution:

  Hemoglobin, present in red blood cells, exhibits a strong affinity for oxygen. It temporarily binds with oxygen to form oxyhemoglobin, facilitating the transportation of oxygen from the lungs to different parts of the body. As for CO2, it is highly soluble in water, hence it is primarily transported in a dissolved form within our blood plasma.

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• Solution:

  Within the lungs, the bronchus bifurcates into smaller and smaller tubes known as bronchioles, ultimately terminating in balloon-like structures called alveoli. These alveoli consist of thin, moist membranes that are abundantly supplied with blood, providing a significantly large surface area for gaseous exchange. It is worth noting that if the alveolar surface were spread out, it would cover an area of approximately 80 square meters.

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• Solution:

  The transportation systems in animals and plants exhibit distinct variations.

  1. Transportation in human beings:

  Human beings rely on a transport system consisting of blood, heart, blood vessels, and lymph. Blood facilitates the transportation of O2, CO2, salts, and nutrients throughout the body. The heart collects deoxygenated blood from various body parts and pumps oxygenated blood. Blood vessels, including arteries, veins, and capillaries, play a vital role. Arteries carry blood away from the heart, while veins collect blood from different organs. The exchange of materials between blood and surrounding cells occurs through the thin walls of capillaries. Lymph, another fluid involved in transportation, carries digested and absorbed fat from the intestine and drains excess fluid from the extracellular space back into the blood.

  2. Transportation in Plants:

  Plants have their own transport system that transports energy stores from leaves and raw materials from roots. This system comprises xylem and phloem. Xylem transports water and minerals obtained from the soil, while phloem transports the products of photosynthesis from the synthesis site to other parts of the plant.

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• Solution:

  Birds and mammals possess tissues with a high metabolic rate that requires the rapid delivery of oxygenated, nutrient-rich blood. To support this need, they maintain high blood pressure. In birds and mammals, double circulation is responsible for maintaining this high blood pressure by separating oxygenated and deoxygenated blood.

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• Solution:

  Highly organized plants have specific transport systems to move energy stores from leaves and raw materials from roots. These systems consist of independent, organized conducting tubes, namely xylem and phloem.

  (i) The xylem transports water and minerals from the roots to the leaves and other plant parts.

  (ii) The phloem transports the products of photosynthesis from the leaves to other plant parts, including the roots.

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• Solution:

  Vessels and tracheids in the xylem tissue of the root, stem, and leaves connect to form a continuous water-conducting channel that reaches all parts of the plant. The cells in contact with the soil in the root absorb ions. To balance the concentration difference between the root and soil, water moves into the root from the soil. Transpiration, the evaporation of water molecules from leaf cells, creates a suction force, pulling water from the xylem cells in the roots. Consequently, transportation aids in the absorption and upward movement of water and minerals from the roots to the leaves.

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• Solution:

  The process of moving soluble products of photosynthesis is referred to as translocation and it takes place through the phloem. In addition to photosynthesis products, the phloem also transports amino acids and various other substances. Translocation of food and other materials occurs within the sieve tubes with the assistance of neighboring companion cells, both in an upward and downward direction. Substances like sucrose are transferred within the phloem tissue utilizing ATP. This results in an increase in the osmotic pressure of the tissue, allowing water to move into it. The pressure created enables the movement of materials within the phloem towards tissues with lesser pressure, ensuring the plant's needs are met.

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  Kidneys are composed of numerous excretory units known as nephrons. Each nephron consists of a cup-shaped structure called Bowman's capsule at its upper end. At the lower end of the Bowman's capsule, there is a U-shaped tube called the tubule. Together, the Bowman's capsule and tubule form the nephron. One end of the tubule is connected to the Bowman's capsule, while the other end is connected to a urine-collecting duct in the kidney. Inside the Bowman's capsule, there is a cluster of blood capillaries called the glomerulus. The glomerulus is connected to the renal artery, which brings blood containing urea waste into it. The glomerulus then exits the Bowman's capsule, and the blood capillaries surround the tubule before joining a renal vein. The main function of the glomerulus is to filter the blood that passes through it. Small molecules such as glucose, water, amino acids, and minerals (excluding blood cells and proteins) pass through the glomerulus via a process called ultrafiltration. As the filtrate moves down the tubule, useful substances like glucose, amino acids, and most of the water are reabsorbed by the capillaries surrounding the tubule. However, waste materials like urea remain in the tubule, resulting in the formation of urine. The nephron carries the urine into the collecting duct of the kidney, from where it is transported to the ureter.

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  Plants eliminate excess water through transpiration. They also shed dead cells and sometimes even parts such as leaves as a means of getting rid of waste. Many waste products in plants are stored within cellular vacuoles, while others are stored as resins and gums in old xylem. Additionally, some plant wastes are excreted into the surrounding soil.

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  The production of urine is regulated by a hormone called anti-diuretic hormone (ADH), which is produced by the anterior pituitary gland. If the blood contains an excess amount of water, a more dilute urine is excreted. This means that less water is reabsorbed and more is expelled. On the other hand, if the blood has a low water content, concentrated urine is excreted. This process is known as osmoregulation.

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  • Response:

    (c) It is incorrect since autotrophs can only convert carbon dioxide and water into carbohydrates in the presence of sunlight. Autotrophs possess chlorophyll, a green pigment that has the ability to capture sun energy. This trapped energy is then used by autotrophs to create food through the process of photosynthesis, where they combine inorganic materials like CO2 and H2O. Any excess food is stored as starch. Autotrophs make up the primary trophic level in food chains.

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  • Response:

    (b) Yeast, mushroom, and bread mold are saprophytes, which means they break down and convert complex organic molecules in dead and decaying matter into simpler substances outside their body. They then absorb these simpler substances in a process known as saprotrophic nutrition. Green plants, on the other hand, are autotrophic organisms that produce their own food through photosynthesis. Amoeba and Paramecium are holozoic organisms that consume solid or fluid organic food, while Cuscuta, lice, and tapeworm are parasitic organisms that survive by deriving food from the bodies of other hosts.

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  • Response:

    (a) Heterotrophs are organisms that cannot produce their own food from inorganic substances like CO2 and water since they lack chlorophyll, which is necessary for capturing solar energy. Examples of heterotrophs include animals, most bacteria, and fungi. These organisms rely on other organisms for their food. Autotrophs, such as green plants, synthesize their own food through photosynthesis by utilizing solar energy.

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    (d) The sequential organs involved in the digestive system are the mouth, esophagus, stomach, small intestine, large intestine, and anus. Human nutrition occurs through the digestive system, which consists of the alimentary canal and associated glands.

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  • Response:

    (b) Human saliva contains an enzyme called salivary amylase, which breaks down starch found in food into sugar. The digestion of carbohydrates begins in the mouth. If saliva is absent, the breakdown of starch is affected. Protein digestion commences in the stomach with the enzyme pepsin and is completed in the small intestine by enzymes such as trypsin, chymotrypsin, carboxy peptidases, amino peptidases, and dipeptidases. Fats are broken down into smaller particles by bile in the small intestine and are further broken down into fatty acids and glycerol by enzymes called lipases, present in pancreatic juice. Absorption of vitamins occurs in the small intestine.

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  • Response:

                      (b) The gastric juice contains glands in the stomach wall that secrete mucus. This mucus plays a vital role in protecting the stomach wall from its own hydrochloric acid secretion. Without mucus, the acid would erode the inner lining of the stomach, leading to the formation of ulcers. Pepsin acts on proteins within the stomach, while salivary amylase, found in saliva, breaks down starch in the mouth. Bile aids in the emulsification of fat within the small intestine.

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  • Response:

       (a) Stomach                                       (b) Small intestine           (c) Large intestine            (d) Oesophagus                 (b) The small intestine receives bile from the liver, which is typically stored in the gall bladder. It has two primary functions: to alkalize the food and break down the fats present in the food into smaller globules through emulsification.

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                      (d) The presence of starch is confirmed when rice water turns blue-black in color. However, proteins or fats will not cause any color change in iodine solution when mixed with them.

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  • Response:

                      (d) In human beings, the small intestine serves as the site for complete digestion of food and is the primary region for absorbing digested food. Though digestion begins in the mouth cavity, further breakdown of food occurs in the stomach, resulting in a semi-solid paste. The undigested food then moves into the large intestine, where most of the water is absorbed.

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  • Response:

                      (d) The pancreas secretes pancreatic juice, which contains various digestive enzymes such as amylases, lipases, and trypsin. Amylase breaks down starch, trypsin digests proteins, and lipase breaks down emulsified fats.

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                      (b) Lime water turns milky due to the presence of carbon dioxide gas. When we blow air from our mouths into a test-tube, the lime water becomes milky because the air we exhale contains more CO2.

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  - Response:

                    (d) The process by which glucose is transformed into pyruvate (glycolysis) occurs within the cytoplasm of the cell. This marks the initial phase of respiration. Following glycolysis, pyruvate undergoes conversion into various compounds depending on whether oxygen is present or absent. This results in the breakdown of glucose through different pathways.

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  - Response:

                (b) Aerobic respiration, which relies on oxygen for the respiration process, takes place within the mitochondria. Once glycolysis occurs, pyruvate from the cytoplasm enters the mitochondria and undergoes oxidation through a series of reactions. This leads to the generation of a substantial amount of energy in the form of ATP, as well as the production of CO2 and H2O.

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