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carbon dioxide
Carbon dioxide supplies carbon for sugars.
Class 6 · English Version · General science
2026 Class 6 Science · English Version · Chapter 5 · Chapter companion part
Chapter 5: Photosynthesis
Explain photosynthesis using inputs, conditions, outputs and evidence.
Class 6 English Version chapter companion with expanded teaching, 20 written tasks and a notebook challenge. Further independent assessment and teacher-reviewed practical work remain; this is not complete textbook coverage.
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Learn the idea
Photosynthesis transfers energy from light into chemical stores in sugars. Green plant cells use carbon dioxide and water to make glucose, with oxygen released. Chlorophyll absorbs light in chloroplasts. The process requires suitable conditions; light is an energy source, not a substance added to the plant.
A leaf suited to the job
A broad leaf can capture light. Thin tissues provide short distances for gases to move. Stomata are pores for gas exchange; veins supply water and carry substances. Chloroplasts in photosynthetic cells contain chlorophyll. Different leaves can have different adaptations.
Evidence and fair testing
A teacher can demonstrate tests for starch or oxygen using suitable precautions. Starch can indicate stored product, but one observation does not measure every photosynthesis factor. For independent practice, compare supplied data and diagrams; do not heat ethanol, handle iodine or test gas with a flame at home.
Food webs and respiration
Photosynthesis supports food chains and contributes oxygen to the atmosphere. Plants also respire day and night. In light, both processes may occur, so net gas movement depends on their relative rates. Sunlight does not replace a plant’s need for water and mineral nutrients.
Separate an input from a condition
Carbon dioxide and water supply matter used to make sugars. Light supplies energy and chlorophyll helps absorb it; neither is an extra chemical substance on the left of the word equation. Oxygen is released, while glucose can be used in respiration or converted to stored starch and other substances. Roots do not take in ready-made starch as the normal source of a green plant’s food.
Interpret a school demonstration
In a teacher’s supplied aquatic-plant demonstration, collected gas that relights a glowing splint is identified as oxygen. This is a reported teacher demonstration, not a home procedure. Bubble count is only a rough comparison because bubble sizes may differ and some gas dissolves. Keep plant amount, time and other relevant conditions alike when comparing light conditions. Use supplied results here; do not collect gases or perform flame/chemical tests independently.
Use evidence rather than just leaf colour
A starch-test comparison can help investigate photosynthesis when the plant was appropriately prepared and suitable controls were used. A blue-black result with iodine indicates starch in the tested material; it does not directly measure every step of photosynthesis or prove that light was the only cause. A leaf’s green colour alone does not demonstrate the amount of sugar made. Teacher-supervised demonstrations require their own risk assessment.
Connect plants, gases and care
Photosynthesis moves carbon into organic food and can release oxygen. Respiration also happens in plants; net gas exchange depends on both processes. Protecting plants supports food webs and habitats, but a plant does not remove every pollutant or make an unsafe room safe. Carbon dioxide is a normal part of the carbon cycle; the amount and context matter, rather than calling every molecule harmful.
Worked example
In a simplified word equation: carbon dioxide + water → glucose + oxygen, with light energy and chlorophyll. The arrow shows the overall change, not that every absorbed gas becomes glucose.
- Identify the evidence, quantity or structure in the question.
- Write a labelled method or explanation; include units where needed.
- Check the model, explain one correction, then attempt the independent task.
Check a common mistake
Photosynthesis is not respiration. Plants do both; they do not stop needing oxygen simply because their leaves release oxygen in light.
Compare supplied bubble observations
A teacher records 12 bubbles in one minute in dim light and 24 in one minute in brighter light, with other relevant conditions held alike. More bubbles were observed in the brighter condition. This supports a comparison under those conditions; it is not an exact oxygen-volume measurement.
A complete written explanation
A grazing animal obtains chemical stores by eating grass. The grass made sugars using light energy, carbon dioxide and water. The animal releases usable energy through respiration. Matter and energy are followed through linked processes, rather than saying the animal eats sunlight.
Your written practice
Show your working on paper and enter your answer here. If it does not match, compare the model and try again.
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oxygen
Oxygen is an output of the process.
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chlorophyll
Chlorophyll is found in chloroplasts.
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glucose
Glucose can be used or converted into other substances.
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stomata
A stoma is one pore; stomata is plural.
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Roots supply water and mineral ions, while green parts use light energy, carbon dioxide and water to make sugars.
Distinguish food production from mineral uptake.
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Either light or water could explain a difference. Keep water and other relevant conditions alike when testing light.
Identify the confounding condition in plain words.
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It eats plants or plant products containing chemical stores made through photosynthesis.
Connect energy transfer to feeding.
Take it further
Apply the idea in a new situation and explain your method. Open writing needs a guardian or teacher to review it.
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starch
Plants can convert glucose into starch.
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output
Oxygen is released by the process.
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chloroplasts
Chlorophyll occurs in chloroplasts.
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oxygen
Oxygen supports this test result; a bubble alone does not identify a gas. Interpret the supplied report rather than doing the test yourself.
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6
18 ÷ 3 = 6 bubbles per minute; bubble count is not a precise gas-volume measurement.
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starch
The test indicates starch in the material tested.
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Light supplies energy, while carbon dioxide and water supply matter for forming the products.
Distinguish energy input from material inputs.
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Equal counts may represent different gas volumes, so count alone is a rough proxy for gas production.
Explain what is counted and what the learner wants to infer.
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The starch could have been present before the interval; preparation and appropriate comparisons are needed.
State the missing starting information.
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Photosynthesis uses particular inputs and produces particular outputs; it is not a universal filter for all harmful substances.
Avoid turning a gas-exchange process into an unsupported safety claim.
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Photosynthesis uses light energy to form sugars; respiration releases usable energy from food and occurs day and night.
Explain different roles and state that both can occur in the same plant.
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Protect existing leaves and suitable growing conditions, or care for a locally appropriate plant with school guidance, preserving food production and habitat.
Explain the biological connection without promising that one action solves all environmental problems.
Your science notebook challenge
Write an investigation report from the supplied bubble observations. Include a question, prediction, comparison, controls, result and one limitation. Draw the photosynthesis word equation and connect its products to an animal food chain.
Review with a guardian or teacher
- Use an observation, labelled diagram or stated data.
- Explain how the evidence supports your answer.
- Record one limitation or correction with a guardian or teacher.
Keep your work on paper or in a local file. This page does not upload it or automatically grade the project.
Chapter companion and further study
This original Kidemy practice follows the topic order of 2026 Class 6 Science · English Version, chapter 5, printed pages 44–48. It does not replace the complete chapter or its practical teaching.
Official book catalogue and source →
Continue with your book or teacher
- An independent investigation interpretation and food-web explanation
- Qualified-teacher review of any real starch or gas demonstration
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