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Class 7 Science: Life Processes in Plants, 8 practice questions with answers

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These are 8 practice questions on Class 7 Science Chapter 10, Life Processes in Plants, of the new NCERT textbook, Curiosity. Each has a worked answer and the textbook page it comes from. They cover photosynthesis and its word equation, how starch is tested and stored, leaves that are not green, stomata, the xylem and the phloem, respiration in plants, and handling alcohol safely in the starch test. Try each one before you open the answer.

These questions are our own, drafted with AI help, and every answer was checked against the textbook page it cites, but no practising teacher has reviewed them yet. If you find a mistake, please tell us.

What the chapter says you need

Facts from the NCERT textbook (Curiosity: Textbook of Science for Grade 7, Chapter 10, printed pages 137 to 152):

Making food

Question 1. Isha writes, "Carbon dioxide + oxygen → glucose + water, in sunlight, with chlorophyll." Find her mistake.

Answer: she has swapped water and oxygen. In photosynthesis, the raw materials are carbon dioxide and water, and the products are glucose and oxygen: carbon dioxide + water → glucose + oxygen, in the presence of sunlight and chlorophyll. Oxygen is given out, not taken in, as the bubbles in Barkha didi's water-plant set-up showed. (Oxygen released, page 145; word equation, page 146.)

Question 2. Kabir says, "A plant makes starch straight away in photosynthesis, and that is all it makes." What is the mistake?

Answer: the food is first made as glucose, which is later converted into starch. During photosynthesis, food is actually produced in the form of glucose, a simple carbohydrate. The glucose serves as an instant source of energy, and later gets converted into starch for storage. (Photosynthesis in a nutshell, page 146.)

Question 3. Rohit's teacher did not keep the potted plant in the dark for two to three days before setting up the caustic soda bottle. After a few hours in sunlight, both halves of the leaf, inside and outside the bottle, turned blue-black with iodine. Why can this result not tell us whether carbon dioxide is needed?

Answer: the leaf already had stored starch before the experiment began. Keeping the plant in the dark lets it lose its stored starch (destarching). Without that step, the half inside the bottle can turn blue-black from old starch, even though it could not make new starch without carbon dioxide. Only a destarched leaf shows that the starch was made during the experiment, where carbon dioxide was available. (Role of air, pages 143 and 144.)

Question 4. Nikhil says, "The leaves of my plant are red, so it cannot make its own food." Find his mistake.

Answer: red leaves can still make food. Some leaves look red, violet or brown because they have more of these coloured pigments than chlorophyll, which hides the green colour. Some of these pigments also help in photosynthesis, and an iodine test on such leaves can show starch, showing that photosynthesis has taken place. (Fascinating facts, page 142.)

Stomata and transport

Question 5. Meera says, "Stomata are holes on a leaf through which the plant drinks water from the soil." Find her mistake.

Answer: stomata are tiny pores that help leaves exchange gases; water comes in through the roots. Water, with minerals from the soil, is taken up by the roots and carried up through the xylem. The stomata, on the surface of leaves, help in the exchange of oxygen and carbon dioxide during photosynthesis and respiration. (Stomata, page 147; nutshell, page 150.)

Question 6. Arjun says, "The xylem carries food down from the leaves, and the phloem carries water up from the roots." Find his mistake.

Answer: he has the two the wrong way round. The xylem transports water and minerals from the roots to the leaves and other parts of the plant. The phloem carries the food made in the leaves to all parts of the plant. (Transport in plants, page 148.)

Respiration

Question 7. Priya says, "Plants make their own food, so only animals need to respire." Find her mistake.

Answer: plants respire too, in every part. In respiration, glucose is broken down using oxygen to release carbon dioxide, water and energy, and plants use this energy for their growth and development. All parts of a plant, green or non-green, carry out respiration. Making food (photosynthesis) and getting energy from it (respiration) are two different processes. (Do plants respire?, page 149.)

Question 8. In the starch test, Arun wants the leaf to lose its colour faster, so he holds the test tube of alcohol straight over the spirit lamp flame. What is he doing wrong?

Answer: alcohol must never be placed near a heat source directly. Alcohol is highly flammable and can easily lead to fire and burns. In the chapter's set-up, the test tube of alcohol is placed in a beaker of boiling water, and the teacher may demonstrate the activity. (Starch test and caution, pages 140 and 141.)

Questions students ask

What is photosynthesis? The process by which plants make their food in the presence of sunlight and chlorophyll, using carbon dioxide from the air and water. It produces glucose and releases oxygen. (Pages 144 and 146.)

Why are leaves called the 'food factories' of plants? Leaves are mostly green because of chlorophyll, and starch is made where the green parts are, in the presence of sunlight. A leaf is the primary site of photosynthesis. (Pages 143 and 144.)

Where is food stored in a plant? The food made in the leaves is carried by the phloem to all parts of the plant, and may be stored in other parts such as seeds and roots, mostly as starch. (Pages 140 and 148.)

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Sources

All opened and read on 22 October 2026. Page numbers are the printed page numbers of the textbook; printed page = PDF page + 136.

The facts are from the textbook pages above. The questions and worked answers are our own. This guide is general information; follow your teacher and the textbook.