Life Processes in Plants | Class 7 Science Notes
By ConceptScroll Team · Published on 17 July 2026 · 3 min read
Life Processes in Plants – this guide gives you a concise, exam-ready overview of Life Processes in Plants from Class 7 Science, written by ConceptScroll editors and reviewed against the latest NCERT textbook.
10.2 How Do Plants Get Food for their Growth?
Unlike animals, plants do not eat food but prepare their own food. This section introduces leaves as the 'food factories' of plants. Leaves are generally broad and flat, containing chlorophyll, a green pigment that captures sunlight efficiently. Plants store food in the form of starch, a carbohydrate produced in leaves. The process of food preparation involves sunlight, chlorophyll, water, and carbon dioxide. The section includes an experiment (Activity 10.2) to test the presence of starch in leaves using iodine solution after decolorizing the leaf with boiling water and alcohol. The blue-black color after iodine application indicates starch presence, confirming that leaves synthesize food. Further, Activity 10.3 demonstrates that only green parts of leaves containing chlorophyll produce starch, highlighting the essential role of chlorophyll in photosynthesis. The section also discusses the role of air (carbon dioxide) in food preparation through Activity 10.4, showing that carbon dioxide is necessary for starch synthesis. Overall, this section explains the process of photosynthesis, the raw materials required, and the role of leaves in food production.
📊 Diagram: Figure 10.2 shows the experimental setup for starch test in leaves including boiling water bath and iodine test application. Figure 10.3 shows the setup to test the role of chlorophyll and air in starch formation using caustic soda in a bottle.
🧪 Activity: Activity 10.2: Starch test in leaves. Activity 10.3: Testing starch in green and non-green leaf patches. Activity 10.4: Testing role of carbon dioxide in photosynthesis using caustic soda.
🔗 Connection: Leads to the section 'Photosynthesis: in a nutshell' explaining the overall process and chemical equation of photosynthesis.
Frequently asked questions
Complete the following table | S.No. | Feature | Photosynthesis | Respiration | | --- | --- | --- | --- | | 1. | Raw materials | | | | 2. | Products | | | | 3. | Word equation | | | | 4. | Importance | | |
1. Raw materials:
- Photosynthesis: Carbon dioxide, water, sunlight
- Respiration: Glucose, oxygen
2. Products:
- Photosynthesis: Glucose, oxygen
- Respiration: Carbon dioxide, water, energy
3. Word equation:
- Photosynthesis: Carbon dioxide + Water + Sunlight → Glucose + Oxygen
- Respiration: Glucose + Oxygen → Carbon dioxide + Water + Energy
4. Importance:
- Photosynthesis: Produces food and oxygen necessary for life
- Respiration: Releases energy required for various life processes
Imagine a situation where all the organisms that carry out photosynthesis on the earth have disappeared. What would be the impact of this on living organisms?
If all photosynthetic organisms disappeared, oxygen levels would decrease as photosynthesis produces oxygen. Food chains would collapse because plants are primary producers. Animals and other organisms dependent on plants for food and oxygen would eventually die, leading to a breakdown of ecosystems.
A potato slice shows the presence of starch with iodine solution. Where does the starch in potatoes come from? Where is the food synthesised in the plant, and how does it reach the potato?
The starch in potatoes comes from the glucose produced during photosynthesis in the leaves. The food is synthesised in the leaves (the food factories) of the plant. The glucose is transported through the phloem to the potato (a storage organ) where it is converted into starch and stored.
Does the broad and flat structure of leaves make plants more efficient for photosynthesis? Justify your answer.
Yes, the broad and flat structure of leaves increases the surface area exposed to sunlight, allowing more light to be absorbed for photosynthesis. It also facilitates efficient gas exchange through stomata, making photosynthesis more efficient.
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