The 'Life Processes' chapter stands as a cornerstone of the Class 10 Science curriculum. As a part of the 'World of Living' unit, it commands a significant weightage of 25 marks in the CBSE board examination, making its thorough preparation non-negotiable for aspiring high-scorers. A deep understanding of the concepts within this chapter not only ensures academic success but also lays a robust foundation for future studies in biology.
In recent years, the Central Board of Secondary Education (CBSE) has initiated a significant paradigm shift in its assessment methodology. The focus has moved away from rote memorization towards competency-based learning. This modern approach prioritizes the evaluation of a student's analytical skills, problem-solving abilities, and the capacity to apply learned concepts to real-life scenarios. Consequently, success in the board examinations now hinges on genuine conceptual clarity rather than superficial knowledge.
This compendium has been meticulously curated to align with this new educational philosophy. The 50 very short answer questions (VSAQs) presented here have been selected after a rigorous analysis of numerous previous years' question papers. The selection criteria were based on the frequency of appearance, the fundamental importance of the concept being tested, and strict adherence to the latest NCERT and CBSE syllabus for the 2025-26 academic The provided solutions are crafted not merely to give an answer but to build the analytical and application-based understanding that the CBSE now seeks to assess.
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| very short answer questions for CBSE Class 10 |
Section 1: Nutrition
Nutrition is the fundamental process by which an organism acquires and utilizes food to obtain energy for maintenance, growth, and repair. The syllabus broadly categorizes nutrition into two modes: autotrophic, where organisms synthesize their own food from simple inorganic substances (e.g., plants through photosynthesis), and heterotrophic, where organisms depend on other organisms for their food (e.g., animals, fungi). The following questions explore the critical aspects of both these modes as frequently tested in board examinations. Curated VSAQs and Solutions
1. Mention the raw materials required for photosynthesis.
Solution: The primary raw materials required for photosynthesis are: Carbon Dioxide (CO_2): Obtained from the atmosphere through stomata. Water (H_2O): Absorbed from the soil by the roots. Sunlight: Trapped by the chlorophyll pigment in the leaves. Chlorophyll: The green pigment present in chloroplasts that absorbs light energy.
2. Write the balanced chemical equation for the process of photosynthesis.
Solution: The balanced chemical equation for photosynthesis is: 6CO_2 + 12H_2O \xrightarrow[\text{Chlorophyll}]{\text{Sunlight}} C_6H_{12}O_6 + 6O_2 + 6H_2O Here, carbon dioxide and water are converted into glucose (food), with oxygen and water released as by-products.
3. How do guard cells regulate the opening and closing of stomatal pores? Solution: The opening and closing of stomatal pores are regulated by the turgor pressure within the guard cells. When water flows into the guard cells from surrounding cells, they become turgid (swollen) and bow outwards, causing the pore to open. Conversely, when the guard cells lose water, they become flaccid (limp) and shrink, causing the pore to close. This mechanism is a prime example of how a biological structure (guard cells) facilitates a critical function (gas exchange and transpiration).
4. In the experiment to prove that carbon dioxide is necessary for photosynthesis, what is the function of potassium hydroxide (KOH) solution?
Solution: In this experiment, potassium hydroxide (KOH) solution is used to absorb all the carbon dioxide present inside the bell jar. This creates an environment devoid of CO_2 for the part of the leaf inside the jar. The subsequent negative result for the starch test in this part of the leaf proves that carbon dioxide is an essential raw material for photosynthesis.
5. Name the green dot-like structures in a leaf cell and state what this green colour is due to.
Solution: The green dot-like structures observed in a leaf cell are chloroplasts. The green colour is due to the presence of a pigment called chlorophyll within these chloroplasts, which is responsible for absorbing sunlight for photosynthesis.
6. What is the mode of nutrition in Amoeba?
Solution: Amoeba exhibits a holozoic mode of nutrition. This involves the ingestion of complex solid organic food, followed by its digestion, absorption, assimilation, and egestion. Amoeba uses temporary finger-like extensions called pseudopodia to engulf its food particle.
7. Differentiate between parasitic and saprophytic nutrition with one example each.
Solution: Parasitic Nutrition: The organism (parasite) derives its nutrition from another living organism (host) without killing it, but causing it harm. Example: Cuscuta (amarbel) on plants, or tapeworms in animals. Saprophytic Nutrition: The organism obtains its nutrition by breaking down dead and decaying organic matter outside its body and then absorbing the nutrients. Example: Fungi like mushrooms and bread mould (Rhizopus).
8. Name the enzyme present in human saliva and state its function.
Solution: The enzyme present in human saliva is salivary amylase (also known as ptyalin). Its function is to begin the chemical digestion of starch (a complex carbohydrate) into simpler sugars (maltose) in the mouth.
9. What is the role of hydrochloric acid (HCl) in the human stomach?
Solution: Hydrochloric acid (HCl) in the stomach serves two main functions: It creates an acidic medium (pH 1.5-3.5) which is essential for the activation and functioning of the protein-digesting enzyme, pepsin. It kills most of the harmful bacteria and other pathogens that may enter the body along with food.
10. Why is the small intestine in herbivores longer than in carnivores?
Solution: Herbivores consume plants, which are rich in cellulose. The digestion of cellulose is a complex and time-consuming process. Therefore, herbivores have a longer small intestine to provide a larger surface area and more time for the complete digestion and absorption of cellulose. Carnivores, on the other hand, eat meat, which is primarily protein and is easier and faster to digest, hence they have a shorter small intestine.
11. What is the specific function of the villi in the small intestine?
Solution: The primary function of villi is to increase the surface area for the absorption of digested food. These small, finger-like projections lining the inner wall of the small intestine are richly supplied with blood vessels, which allows them to efficiently absorb the digested nutrients and transport them into the bloodstream. This structure-function relationship is a key adaptation for maximizing nutrient uptake.
12. Name the part of the alimentary canal that receives bile from the liver. What is the function of bile?
Solution: The small intestine receives bile from the liver. Bile performs two crucial functions: It emulsifies large fat globules into smaller fat droplets, increasing the surface area for the enzyme lipase to act upon and digest them. It makes the acidic food coming from the stomach alkaline, creating the optimal pH for the pancreatic and intestinal enzymes to function.
13. What is the mode of nutrition in fungi?
Solution: Fungi exhibit a saprophytic (or saprotrophic) mode of nutrition. They secrete digestive enzymes onto dead and decaying organic matter, breaking it down externally into simpler soluble forms, which are then absorbed by the fungal hyphae.
14. Where does the digestion of starch begin in the human body?
Solution: The digestion of starch begins in the mouth. The enzyme salivary amylase, present in saliva, starts breaking down starch into simpler sugars.
15. What would happen if the mucus is not secreted by the gastric glands?
Solution: If mucus were not secreted by the gastric glands, the inner lining of the stomach would be exposed to the highly corrosive action of hydrochloric acid (HCl) and the protein-digesting enzyme pepsin. This would lead to the erosion of the stomach wall, causing acidity, gastritis, and potentially peptic ulcers.
Section 2: Respiration
Respiration is a vital life process that involves the breakdown of food molecules to release energy in the form of ATP (Adenosine Triphosphate). It is crucial to distinguish breathing (the physical act of gas exchange) from cellular respiration (the chemical process of energy release within cells). Cellular respiration can be aerobic (occurring in the presence of oxygen) or anaerobic (occurring in the absence of oxygen), following different metabolic pathways to break down glucose. Curated VSAQs and Solutions
16. Differentiate between aerobic and anaerobic respiration based on their end products.
Solution: Aerobic Respiration: The end products are carbon dioxide (CO_2), water (H_2O), and a large amount of energy (approx. 38 ATP). Anaerobic Respiration: The end products in yeast are ethanol, carbon dioxide (CO_2), and a small amount of energy (2 ATP). In human muscle cells, the end product is lactic acid and a small amount of energy.
17. Name the site of the breakdown of glucose into pyruvate in a cell.
Solution: The breakdown of a six-carbon glucose molecule into a three-carbon molecule called pyruvate occurs in the cytoplasm of the cell. This process is known as glycolysis and is the common first step for both aerobic and anaerobic respiration.
18. What causes muscle cramps during sudden, vigorous physical activity?
Solution: During vigorous physical activity, the demand for oxygen by the muscle cells can exceed the supply. In this situation, the muscle cells switch to anaerobic respiration to produce energy. This process results in the accumulation of lactic acid in the muscles, which causes fatigue and painful cramps.
19. Why are the rings of cartilage present in the trachea (windpipe)?
Solution: The trachea is supported by C-shaped rings of cartilage. These rings are rigid and prevent the airway from collapsing when there is less air in it during exhalation, thus ensuring an unobstructed passage for air to and from the lungs.
20. How are the alveoli designed to maximize the exchange of gases?
Solution: The alveoli are designed for maximum gas exchange in several ways: Large Surface Area: The lungs contain millions of alveoli, providing a vast surface area (about 80 square meters) for diffusion. Thin Walls: The walls of the alveoli and the surrounding capillaries are extremely thin (one-cell thick), minimizing the diffusion distance for gases. Rich Blood Supply: They are covered by an extensive network of blood capillaries, ensuring efficient transport of gases to and from the bloodstream.
21. Why is the rate of breathing in aquatic organisms much faster than in terrestrial organisms?
Solution: This difference is due to the principle of efficiency in obtaining oxygen. The concentration of dissolved oxygen in water is significantly lower than the concentration of oxygen in the air. To obtain the required amount of oxygen from this low-oxygen medium, aquatic organisms like fish must pass a large volume of water over their gills, resulting in a much faster rate of breathing compared to terrestrial organisms.
22. Name the respiratory pigment in human beings and state its role.
Solution: The respiratory pigment in human beings is hemoglobin. Its primary role is to bind with oxygen in the lungs and transport it via the bloodstream to all the body tissues where it is required for cellular respiration. Hemoglobin has a very high affinity for oxygen, making it an extremely efficient oxygen carrier. This molecule is a perfect example of the link between the respiratory and transport systems.
23. When air is blown from the mouth into a test tube containing lime water, the lime water turns milky. What does this indicate?
Solution: Lime water (calcium hydroxide solution) turns milky (forms a white precipitate of calcium carbonate) in the presence of carbon dioxide. This observation indicates that the air we exhale is rich in carbon dioxide, which is a waste product of cellular respiration in our body.
24. Where does the breakdown of pyruvate using oxygen take place?
Solution: In aerobic respiration, the complete breakdown of pyruvate using oxygen takes place inside the mitochondria. This process releases a large amount of energy, which is stored in ATP molecules.
25. What advantage does a terrestrial organism have over an aquatic organism with regard to obtaining oxygen for respiration?
Solution: The primary advantage for a terrestrial organism is the high concentration of oxygen in the atmosphere (about 21%) compared to the very low concentration of dissolved oxygen in water. This allows terrestrial organisms to expend less energy in the process of breathing to meet their metabolic demands.
26. Why do woody plants carry out gaseous exchange through lenticels?
Solution: In older, woody stems, the epidermis is replaced by a layer of bark which is impermeable to gases. Lenticels are small pores in the bark that allow for the exchange of respiratory gases (oxygen and carbon dioxide) between the internal tissues of the stem and the atmosphere.
27. What is the residual volume of air in the lungs? State its importance.
Solution: Residual volume is the volume of air that remains in the lungs even after a forceful exhalation. Its importance is that it allows for the continuous exchange of gases between the blood and the alveoli, even during exhalation, and prevents the lungs from collapsing.
Section 3: Transportation
In complex multicellular organisms, simple diffusion is inadequate for transporting essential substances like oxygen, nutrients, and hormones to all cells and for removing waste products. This necessitates a specialized transport system. In humans, this is the circulatory system, comprising the heart, blood, and blood vessels. In plants, the vascular tissues, xylem and phloem, perform this function. Curated VSAQs and Solutions
28. Name the component of blood that helps in the formation of a blood clot.
Solution: Platelets (or thrombocytes) are the components of blood responsible for initiating the process of blood clotting at the site of an injury, thereby preventing excessive blood loss.
29. State one structural difference between an artery and a vein.
Solution: Arteries have thick, elastic, muscular walls to withstand the high pressure of blood being pumped from the heart. In contrast, veins have thinner walls as the blood pressure within them is much lower. Additionally, veins have valves to prevent the backflow of blood, which are absent in arteries.
30. What is meant by 'double circulation' in the human heart?
Solution: Double circulation is a system in which blood flows through the heart twice for each complete circuit of the body. It consists of two circuits: Pulmonary Circulation: Moves deoxygenated blood from the heart to the lungs and brings oxygenated blood back to the heart. Systemic Circulation: Moves oxygenated blood from the heart to the rest of the body and brings deoxygenated blood back to the heart.
31. Which blood vessel carries deoxygenated blood from the heart to the lungs?
Solution: The pulmonary artery carries deoxygenated blood from the right ventricle of the heart to the lungs for oxygenation. This is a critical exception to the general rule that arteries carry oxygenated blood. The defining characteristic of an artery is that it carries blood away from the heart, irrespective of its oxygenation status.
32. What is the function of valves present in the heart?
Solution: The valves in the heart ensure that blood flows in only one direction. They open to allow blood to pass from the atria to the ventricles and from the ventricles into the major arteries, and then close to prevent any backflow of blood during the contraction of the heart chambers.
33. What is lymph or tissue fluid?
Solution: Lymph is a colorless fluid that is formed when some plasma, proteins, and blood cells escape from the blood capillaries into the intercellular spaces in the tissues. It collects waste products and drains back into the bloodstream through the lymphatic system. It also plays a vital role in the body's immune system.
34. What is the function of xylem tissue in plants?
Solution: The primary function of xylem tissue is the transport of water and dissolved minerals from the roots to all other parts of the plant, such as the stem and leaves. It also provides mechanical strength and support to the plant body.
35. Name the tissue that transports soluble products of photosynthesis in a plant.
Solution: Phloem is the vascular tissue responsible for transporting the soluble products of photosynthesis (mainly sucrose) from the leaves (the site of production) to other parts of the plant like roots, fruits, and seeds for use or storage.
36. Define 'translocation' as it relates to plants.
Solution: Translocation is the process of transporting food, synthesized in the leaves during photosynthesis, to various storage organs and growing parts of the plant. This transport occurs through the phloem tissue and requires energy in the form of ATP.
37. Name the process in plants by which water is lost in the form of water vapour.
Solution: The process is called transpiration. It is the evaporative loss of water from the aerial parts of the plant, primarily through the stomata on the leaves.
38. How does transpiration help in the upward movement of water in tall plants?
Solution: Transpiration creates a suction pressure, often called the 'transpirational pull,' from the top of the plant. This process involves fundamental principles of physics. As water evaporates from the leaf surfaces, it generates a negative pressure potential in the xylem. Due to the cohesive forces between water molecules and the adhesive forces between water and the xylem walls, this pull is transmitted down the entire water column, effectively drawing water up from the roots against gravity.
39. Which chamber of the human heart has the thickest muscular wall?
Solution: The left ventricle has the thickest muscular wall. This is because it is responsible for pumping oxygenated blood with high pressure to all parts of the body through the systemic circulation, which requires a much stronger contractile force than any other chamber.
40. What do the pulmonary veins transport?
Solution: The pulmonary veins transport oxygenated blood from the lungs back to the left atrium of the heart. This is the other major exception to the general rules of blood vessels, as veins typically carry deoxygenated blood. The defining characteristic of a vein is that it carries blood towards the heart.
Section 4: Excretion
Excretion is the biological process of removing harmful nitrogenous metabolic wastes from the body to maintain a constant internal environment, a state known as homeostasis. It is important to distinguish this from egestion, which is the removal of undigested food. In humans, the primary excretory system involves the kidneys, which filter blood to produce urine. Plants also have mechanisms to remove their waste products. Curated VSAQs and Solutions
41. Define excretion.
Solution: Excretion is the biological process by which an organism removes harmful metabolic waste products, such as urea, uric acid, and ammonia, from its body.
42. Name the basic filtration unit present in the human kidney.
Solution: The basic filtration and functional unit of the human kidney is the nephron. Each kidney contains approximately one million nephrons.
43. What is the procedure used in artificial kidneys to clean the blood of a person called?
Solution: The procedure is called hemodialysis, or simply dialysis. It involves filtering a patient's blood through a machine (a dialyzer or artificial kidney) to remove waste products like urea and excess salts when their own kidneys are unable to perform this function.
44. Which blood vessel has blood with a lower concentration of nitrogenous waste: the renal artery or the renal vein? Give a reason.
Solution: The renal vein has blood with a lower concentration of nitrogenous waste. This is because the renal artery brings unfiltered blood containing a high concentration of urea to the kidney. The kidney then filters this blood, removing the urea and other wastes to form urine. The purified blood, now with very little urea, exits the kidney through the renal vein. This question directly tests the understanding of the kidney's primary function: blood purification.
45. List two ways by which plants excrete their waste products.
Solution: Plants excrete their waste products in several ways: Gaseous Wastes: Carbon dioxide (from respiration) and oxygen (from photosynthesis) are removed through stomata and lenticels. Stored Wastes: Some solid and liquid wastes are stored in cell vacuoles or in leaves, bark, and fruits, which are then shed from the plant. Wastes may also be stored as gums and resins, especially in old xylem.
46. Name the hormone responsible for the reabsorption of water in the nephron. Solution: The hormone responsible for regulating the reabsorption of water in the collecting duct of the nephron is the Antidiuretic Hormone (ADH), also known as vasopressin.
47. What is the main nitrogenous waste in human blood that is removed by the kidneys?
Solution: The main nitrogenous waste product in human blood is urea. It is produced in the liver from the breakdown of proteins and is then transported by the blood to the kidneys for filtration and removal in urine.
48. Why do fishes die when taken out of water?
Solution: Fishes respire through gills, which are adapted to extract dissolved oxygen from water. When a fish is taken out of water, its delicate gill filaments stick together and collapse, drastically reducing the surface area available for gas exchange. As a result, the fish cannot absorb sufficient oxygen from the air and dies from suffocation.
49. Name the excretory organ in Amoeba.
Solution: Amoeba, being a unicellular organism, does not have a specialized excretory organ. Waste products like ammonia and carbon dioxide are removed directly from the cell into the surrounding water by the process of diffusion through its cell membrane. The contractile vacuole also plays a role in osmoregulation, expelling excess water.
50. What constitutes the urine formed in the nephron?
Solution: Urine is primarily composed of water (about 95%), urea (about 2.5%), and other dissolved waste products such as uric acid, creatinine, and various mineral salts (ions like sodium, potassium, and chloride).
Conclusion: Strategic Insights for Exam Excellence This curated compendium of 50 high-impact VSAQs provides a strategic pathway to mastering the 'Life Processes' chapter. The analysis of these questions from previous board examinations reveals several recurring themes and patterns that, when understood, can significantly enhance exam performance. A prominent pattern is the emphasis on the relationship between structure and function; questions frequently assess how a biological component, such as the alveoli or intestinal villi, is structurally adapted to perform its physiological role efficiently. Similarly, comparative questions, like those contrasting aquatic and terrestrial respiration or arteries and veins, are designed to test a deeper, more nuanced understanding of underlying principles rather than simple definitions. To excel in answering VSAQs in the board examination, students should adopt the following strategies: Precision with Keywords: Use accurate and specific biological terminology. For instance, use 'translocation' for the transport of food in plants and 'hemoglobin' for the respiratory pigment. Correct terminology demonstrates a strong command of the subject. Answer in Context: Read each question carefully and provide only the information that is explicitly asked. For a 1-mark question, a concise and direct answer is more effective than a lengthy explanation with irrelevant details. This saves valuable time during the examination. Embrace Inter-topic Connections: Recognize that biological systems are integrated. Questions often bridge concepts, such as linking the respiratory pigment (respiration) with its role in the circulatory system (transportation). Understanding these connections leads to a more holistic and sophisticated grasp of the subject. Ultimately, preparation for the CBSE board examination is a marathon, not a sprint. Consistent practice and a focus on building genuine conceptual clarity are the keys to success. By working through these selected questions and understanding the logic behind their solutions, students can build the confidence and competence needed to not only answer questions accurately but also to apply their knowledge effectively, aligning perfectly with the modern, competency-based approach of the CBSE.
