Life Processes Class 10 Science — Competency Based Questions

20 Questions | 70 Marks

Case Study: A student, Priya, is observing a plant under a microscope. She notices small pores on the surface of the leaves. She learns that these pores are called stomata and are involved in gas exchange. She also reads that stomata can open and close.(a) What is the primary function of stomata in relation to photosynthesis? [1 mark](b) Explain how the opening and closing of stomata are controlled. [2 marks](c) Under what environmental conditions might stomata close, and why? 2marks

Scenario: A group of students is discussing the energy requirements of living organisms. Rohan claims that all living things get their energy from consuming other organisms.(a) Identify the type of nutrition Rohan is describing. [1 mark](b) Name the alternative mode of nutrition where organisms prepare their own food. [1 mark](c) Give one example of an organism that uses the mode of nutrition described by Rohan and one example of an organism that uses the alternative mode. 2marks

Assertion (A): Aerobic respiration releases more energy than anaerobic respiration.Reason (R): Aerobic respiration involves the complete breakdown of glucose in the presence of oxygen. 1mark

Application: A doctor advises a patient with severe cramps in their leg muscles to rest and consume a balanced diet. The patient wonders why this advice is given, considering the cramps are due to a lack of exercise.Explain the physiological process that leads to cramps in muscle cells under conditions of oxygen deficiency, and how rest and a balanced diet might help. 3marks

Case Study: A farmer observes that his crops are not growing well despite adequate watering. He notices that the leaves are yellowish and the soil appears to be lacking certain nutrients.(a) What essential elements are typically absorbed from the soil by plants, and what are their roles? [2 marks](b) How does the plant transport these absorbed elements from the roots to the leaves? [2 marks](c) If the leaves are yellowish, which specific nutrient deficiency is likely, and why is it crucial for photosynthesis? 2marks

Assertion (A): The rate of photosynthesis decreases significantly in the absence of sunlight.Reason (R): Sunlight provides the energy required to convert carbon dioxide and water into glucose. 1mark

Scenario: Two friends, Amit and Sumit, are discussing how their bodies get rid of waste products. Amit mentions that his body gets rid of waste when he exhales. Sumit talks about a specific organ that filters blood.(a) Identify the gaseous waste product that Amit is referring to and the process by which it is removed. [2 marks](b) Identify the organ Sumit is referring to and the primary nitrogenous waste product it removes from the blood. [2 marks](c) Briefly describe the functional unit of the organ Sumit mentioned. 2marks

Application: Imagine a situation where there is a sudden blockage in the major artery supplying blood to your brain.(a) What would be the immediate consequences of this blockage? [2 marks](b) Name the substance that helps to prevent such blockages by clotting blood at the site of an injury. 1mark

Case Study: A student is dissecting a flower and observes that it has a complex vascular system. They are curious about how water and food are transported within the plant.(a) Name the two main types of vascular tissues in plants. [1 mark](b) Which vascular tissue is responsible for transporting water and minerals from the roots to the leaves? [1 mark](c) Explain how transpiration contributes to the upward movement of water in plants. 3marks

Assertion (A): The walls of arteries are thicker and more elastic than those of veins.Reason (R): Arteries carry blood away from the heart to all parts of the body under high pressure. 1mark

Scenario: A biology class is studying the digestive system. The teacher explains that complex food molecules are broken down into simpler ones.(a) What is the role of enzymes in digestion? [2 marks](b) Name one enzyme secreted in the small intestine and the food component it acts upon. [2 marks](c) Why is the small intestine highly coiled? 1mark

Application: A person suffering from high blood pressure is advised to reduce their salt intake.(a) What is high blood pressure (hypertension)? [1 mark](b) How might reducing salt intake help in managing hypertension? 2marks

Case Study: In a biology lab, students are performing an experiment to demonstrate the release of carbon dioxide during respiration. They use yeast mixed with sugar solution in a test tube fitted with a bent glass tube, with the other end dipped in lime water.(a) What is the expected observation in the lime water, and why? [2 marks](b) Name the process occurring in the test tube. [1 mark](c) Is this process aerobic or anaerobic? Justify your answer. 2marks

Assertion (A): Plants do not have a circulatory system like humans.Reason (R): Plants have lower energy requirements and utilize slow transport systems like diffusion and transpiration. 1mark

Application: A patient has to undergo dialysis.(a) What is dialysis, and why is it performed? [2 marks](b) Briefly explain the principle behind dialysis. 2marks

Scenario: A group of students is discussing the efficiency of energy production in different organisms. They compare the energy yield from different metabolic pathways.(a) Name the molecule that serves as the energy currency of the cell. [1 mark](b) Which process of glucose breakdown yields the maximum amount of ATP? [1 mark](c) Where does the process mentioned in (b) primarily occur within the cell? 1mark

Case Study: A plant is kept in a dark room for three days, then one plant is kept with a watch glass of potassium hydroxide and another without, and then both are placed in sunlight.(a) What is the purpose of keeping the plant in a dark room for three days? [1 mark](b) What is the role of potassium hydroxide in this experiment? [1 mark](c) What observation would lead to the conclusion that carbon dioxide is essential for photosynthesis? 2marks

Assertion (A): The rate of breathing in aquatic organisms is faster than in terrestrial organisms.Reason (R): The amount of dissolved oxygen in water is much lower than the amount of oxygen in the atmosphere. 1mark

Application: A person is diagnosed with a deficiency of haemoglobin.(a) What is haemoglobin, and where is it found in the human body? [2 marks](b) What are the likely consequences of a deficiency of haemoglobin? 2marks

Scenario: A student is studying the double circulation in humans. They are confused about why the right and left sides of the heart are separated.(a) Explain the terms 'oxygenated blood' and 'deoxygenated blood'. [2 marks](b) Why is the separation of oxygenated and deoxygenated blood important in humans? [2 marks](c) Name one group of animals that has a three-chambered heart and experiences some mixing of blood. 1mark

Answers

1.(a) The primary function of stomata is to facilitate the exchange of gases, namely carbon dioxide (

C O_{2}

) for photosynthesis and oxygen (

O_{2}

) as a byproduct, as well as water vapour during transpiration. [1 mark](b) The opening and closing of stomata are controlled by guard cells. When water flows into the guard cells, they swell, causing the stomatal pore to open. When guard cells lose water and shrink, the pore closes. [2 marks](c) Stomata may close during conditions of water scarcity (drought) or high temperatures to minimize water loss through transpiration. They also close when the plant does not need carbon dioxide for photosynthesis, such as at night. 2marks

2.
(a) Heterotrophic nutrition. [1 mark]
(b) Autotrophic nutrition. [1 mark]
(c) Example of heterotrophic organism: Lion. Example of autotrophic organism: Green plant (e.g., Mango tree). [2 marks]

3.
Assertion (A) is true and Reason (R) explains Assertion (A). Aerobic respiration, by completely breaking down glucose in the presence of oxygen, yields significantly more ATP (energy) compared to anaerobic respiration, which involves incomplete breakdown. [1 mark]

4.
(a) During sudden strenuous activity, when the oxygen supply to muscle cells is insufficient for aerobic respiration, pyruvate is converted to lactic acid through anaerobic respiration. This build-up of lactic acid in the muscle cells causes fatigue and painful cramps. [2 marks]
(b) Rest allows the muscles to recover and the lactic acid to be converted back into pyruvate or glucose, which can then be further broken down aerobically. A balanced diet ensures the availability of glucose and other nutrients necessary for efficient energy production and muscle repair. [2 marks]

5.
(a) Essential elements include nitrogen (for protein synthesis), phosphorus (for cell membranes and DNA), and magnesium (for chlorophyll). [2 marks]
(b) Water and minerals are transported from the roots to the leaves through the xylem tissue. [2 marks]
(c) Yellowish leaves often indicate a deficiency in magnesium, which is a key component of chlorophyll. Without sufficient chlorophyll, the plant cannot efficiently capture sunlight for photosynthesis, leading to reduced growth. [2 marks]

6.
Assertion (A) is true and Reason (R) is true and is the correct explanation for Assertion (A). Photosynthesis is a light-dependent process where sunlight provides the energy to drive the conversion of raw materials into food. [1 mark]

7.
(a) The gaseous waste product Amit is referring to is carbon dioxide ( $C O_{2}$ ). It is removed through exhalation during respiration. [2 marks]
(b) Sumit is referring to the kidneys. The primary nitrogenous waste product removed by the kidneys is urea. [2 marks]
(c) The functional unit of the kidney is the nephron, which consists of Bowman's capsule and a renal tubule. [2 marks]

8.
(a) A blockage in a major artery supplying blood to the brain would cause a stroke, leading to a sudden loss of brain function, paralysis, speech difficulties, or even death, due to the lack of oxygen and nutrients to brain cells. [2 marks]
(b) Platelets help to form a clot at the site of an injury, preventing excessive blood loss. [1 mark]

9.
(a) The two main types of vascular tissues are xylem and phloem. [1 mark]
(b) Xylem is responsible for transporting water and minerals. [1 mark]
(c) Transpiration is the process of water loss in the form of vapour from the aerial parts of the plant, primarily through stomata. This evaporation creates a 'transpirational pull' or suction force that pulls water from the xylem in the leaves. This pull extends down the xylem vessels, drawing water from the roots up to the leaves, effectively transporting water and dissolved minerals against gravity. [3 marks]

10.
Assertion (A) is true and Reason (R) is true and is the correct explanation for Assertion (A). Arteries need thick, elastic walls to withstand the high pressure of blood pumped from the heart. [1 mark]

11.
(a) Enzymes are biological catalysts that speed up the rate of digestion by breaking down complex food molecules into simpler, absorbable ones without being consumed in the process. [2 marks]
(b) In the small intestine, lipase acts on emulsified fats to break them down into fatty acids and glycerol. Trypsin digests proteins into amino acids. [2 marks]
(c) The small intestine is highly coiled to increase its surface area for efficient absorption of digested food. [1 mark]

12.
(a) High blood pressure, or hypertension, is a condition where the force of blood against the artery walls is consistently too high. [1 mark]
(b) High salt intake can cause the body to retain water, increasing blood volume and thus blood pressure. Reducing salt intake helps to reduce water retention and consequently lower blood pressure. [2 marks]

13.
(a) The lime water will turn milky. This is because the yeast, in the absence of sufficient oxygen, undergoes fermentation, producing carbon dioxide ( $C O_{2}$ ) which reacts with the calcium hydroxide in lime water to form insoluble calcium carbonate, making it milky. [2 marks]
(b) Fermentation (or anaerobic respiration). [1 mark]
(c) This process is anaerobic because it occurs in the absence of air (oxygen) and produces ethanol and carbon dioxide as byproducts, typical of anaerobic respiration in yeast. [2 marks]

14.
Assertion (A) is true and Reason (R) is true and is the correct explanation for Assertion (A). While plants do not have a specialized circulatory system like animals, they have efficient transport mechanisms (xylem and phloem) to move water, minerals, and food, which suffice for their lower metabolic and energy needs. [1 mark]

15.
(a) Dialysis is an artificial process used to remove waste products and excess fluid from the blood when the kidneys are not functioning properly. It is performed to prevent the accumulation of toxic substances in the body. [2 marks]
(b) Dialysis works on the principle of diffusion. The patient's blood is passed through a semi-permeable membrane surrounded by a dialysing fluid. Waste products and excess electrolytes diffuse from the blood into the dialysing fluid (which has a lower concentration of these substances), while essential substances remain in the blood. [2 marks]

16.
(a) ATP (Adenosine Triphosphate) is known as the energy currency of the cell. [1 mark]
(b) Aerobic respiration. [1 mark]
(c) Mitochondria. [1 mark]

17.
(a) Keeping the plant in a dark room for three days removes any stored starch from the leaves, ensuring that any starch present after the experiment is a result of photosynthesis during the experiment. [1 mark]
(b) Potassium hydroxide ( $K O H$ ) absorbs carbon dioxide from the air. [1 mark]
(c) If the leaf from the plant kept with potassium hydroxide does not show the presence of starch (tested with iodine solution) while the leaf from the plant kept without $K O H$ does show the presence of starch, it would indicate that carbon dioxide is essential for photosynthesis. [2 marks]

18.
Assertion (A) is true and Reason (R) is true and is the correct explanation for Assertion (A). Aquatic organisms need to extract oxygen from water, which has a lower concentration of dissolved oxygen compared to atmospheric air. This necessitates a faster rate of breathing to obtain sufficient oxygen. [1 mark]

19.
(a) Haemoglobin is a red pigment found in red blood corpuscles (RBCs) in human blood. Its primary function is to transport oxygen from the lungs to the body tissues. [2 marks]
(b) A deficiency of haemoglobin (anemia) leads to reduced oxygen-carrying capacity of the blood. This can cause symptoms like fatigue, weakness, shortness of breath, paleness, and reduced physical and mental capacity. [2 marks]

20.
(a) Oxygenated blood is blood that is rich in oxygen, having picked it up from the lungs. Deoxygenated blood is blood that has returned from the body tissues, carrying a higher concentration of carbon dioxide and a lower concentration of oxygen. [2 marks]
(b) The separation of oxygenated and deoxygenated blood is important in humans (and other warm-blooded animals) to maintain a high metabolic rate and supply sufficient oxygen to meet the high energy demands required for maintaining a constant body temperature. Mixing would reduce the efficiency of oxygen delivery. [2 marks]
(c) Amphibians (e.g., frogs) or many reptiles have a three-chambered heart. [1 mark]

Download as PDF opens your browser's print dialog: choose Save as PDF as the printer.

Life Processes — Competency Based Questions

Competency based questions

Answers

All Class 10 Science chapters