Life Processes Competency-Based Questions Class 10 with Answers
Life Processes Competency-Based Practice
Apply your understanding of nutrition, respiration, transportation and excretion through experiment-based, case-based, assertion–reason and scientific-reasoning questions. Check each answer immediately and use the topic diagnosis to decide what to revise.
Resource overview
20 single-select questions with one unambiguously correct answer.
Five questions each from nutrition, respiration, transportation and excretion.
One mark per correct answer. Incorrect and unanswered questions receive zero marks.
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Important: These are original competency-based practice questions, not claimed PYQs or an official CBSE paper.
Learning outcomes
- Interpret observations from experiments involving photosynthesis and respiration.
- Connect organ structure with functions such as absorption and gaseous exchange.
- Apply concepts of xylem, phloem, circulation and blood components.
- Explain filtration, selective reabsorption, dialysis and excretion in plants.
- Use evidence to distinguish a correct explanation from a related but incomplete statement.
Quick revision before you begin
Photosynthesis needs carbon dioxide, water, chlorophyll and light. Digestion converts complex food into absorbable substances.
Cellular respiration releases energy from food. Aerobic respiration releases more usable energy than anaerobic pathways.
Xylem transports water and minerals. Phloem transports soluble products of photosynthesis to different plant parts.
Nephrons filter blood and selectively reabsorb useful substances. Plants use several methods to remove or store wastes.
A destarched plant has part of one leaf covered with opaque black paper. The plant is kept in sunlight for several hours. The leaf is then tested with iodine.
Explanation: The plant was destarched first, so any starch detected afterwards was newly formed. The uncovered region received light and could photosynthesise; the covered region could not. Iodine turns blue-black where starch is present.
Two similar destarched plants are placed under separate airtight bell jars in sunlight. Jar P contains potassium hydroxide, which absorbs carbon dioxide. Jar Q does not contain potassium hydroxide.
Explanation: Potassium hydroxide removes carbon dioxide from jar P. With other relevant conditions kept similar, the absence of starch in P shows that carbon dioxide is required for photosynthesis.
Explanation: Stomata provide pathways for carbon dioxide to enter and water vapour to leave. Closing them conserves water but can also reduce the carbon dioxide available for photosynthesis.
Explanation: Villi and microvilli greatly increase the absorptive surface of the small intestine. Damage to them reduces the transfer of digested nutrients into the blood and lymph.
Explanation: Bile breaks large fat globules into smaller droplets, increasing the area on which lipase can act. It also helps neutralise the acidic food entering from the stomach and supports an alkaline medium in the small intestine.
Germinating seeds are placed in an insulated flask. A thermometer shows that the temperature inside the flask gradually rises.
Explanation: Germinating seeds respire actively. During respiration, chemical energy from food is released; some is captured for cellular work and some is released as heat, causing the temperature rise.
Yeast is added to a warm sugar solution in a closed flask connected to a balloon. After some time, the balloon inflates.
Explanation: In limited oxygen, yeast breaks down sugar to form ethanol, carbon dioxide and a small amount of released energy. The accumulated carbon dioxide inflates the balloon.
Explanation: When oxygen is temporarily insufficient, muscle cells can convert pyruvate into lactic acid and release less usable energy than in aerobic respiration. Delayed muscle soreness should not be explained simply as lactic acid remaining in muscles.
Explanation: Numerous alveoli provide a large surface area. Their thin, moist walls and dense capillary network allow oxygen and carbon dioxide to diffuse across a short distance efficiently.
Assertion (A): Breathing rate usually increases during exercise.
Reason (R): Active muscles respire faster, increasing oxygen demand and carbon dioxide production.
Explanation: Both statements are true. Faster breathing helps deliver oxygen required for increased aerobic respiration and helps remove the additional carbon dioxide produced by active tissues.
A narrow ring of bark is removed from around a woody stem without seriously damaging the inner wood. After some time, swelling appears just above the removed ring.
Explanation: Phloem lies in the bark region and transports soluble food from sources such as leaves to other parts. Removing a ring of bark interrupts this translocation, causing food to accumulate above the ring.
A freshly cut leafy shoot is placed in coloured water. Later, coloured lines are visible in the stem and leaf veins.
Explanation: Xylem conducts water and dissolved minerals from roots or a cut stem towards leaves. The coloured pathway therefore reveals the position of xylem vessels.
Explanation: The left ventricle must generate enough pressure to send oxygenated blood throughout the body. The right ventricle pumps only to the lungs, so it requires a less muscular wall.
Explanation: A four-chambered heart keeps oxygen-rich and oxygen-poor blood separate. This supports efficient oxygen supply needed for the high energy demands of humans and other mammals.