Life Processes in Plants — Class 7 (Chapter 10)
Simple English • Mobile-friendly • With Hindi word meanings & full chapter notes
1) 20 Important Words (with simple meanings in Hindi)
| Word | Simple meaning in Hindi (सरल अर्थ) |
|---|---|
| Photosynthesis | प्रकाश संश्लेषण — पौधे प्रकाश, जल और वायु से भोजन (ग्लूकोज़) बनाते हैं। |
| Chlorophyll | हरित वर्णक — पत्तियों का हरा रंग; धूप पकड़ने में मदद करता है। |
| Starch | मंड/स्टार्च — पत्तियाँ बने हुए भोजन को इसी रूप में जमा करती हैं। |
| Glucose | ग्लूकोज़ — सरल शर्करा; पत्तियाँ इसे बनाती हैं, बाद में स्टार्च में बदल सकता है। |
| Stomata | रंध्र — पत्ती की सतह पर सूक्ष्म छिद्र; गैसों का आदान-प्रदान करते हैं। |
| Xylem | जाइलम — जड़ों से पानी व खनिज ऊपर ले जाने वाली नलिकाएँ। |
| Phloem | फ्लोएम — पत्तियों से बना भोजन पूरे पौधे तक पहुँचाने वाली नलिकाएँ। |
| Minerals | खनिज लवण — मिट्टी से मिलने वाले आवश्यक पोषक (जैसे नाइट्रेट, फॉस्फेट)। |
| Respiration (in plants) | श्वसन — ग्लूकोज़ + ऑक्सीजन से ऊर्जा बनती है; CO₂ व जल बनते हैं। |
| Destarching | स्टार्च हटाना — पौधे को अँधेरे में रखकर पत्तियों से जमा भोजन खत्म करना। |
| Iodine test | आयोडीन जाँच — स्टार्च होने पर नीला-काला रंग आता है। |
| Variegated leaf | विविधवर्णी पत्ती — हरी और गैर-हरी चितकबरी पत्ती (सिर्फ़ हरे भाग में क्लोरोफिल)। |
| Chloroplast | हरितलवक — पत्तियों/हरे भागों की कोशिकाओं में क्लोरोफिल वाला भाग। |
| Pigment | वर्णक — रंग देने वाले रसायन (कई बार हरे रंग को ढक लेते हैं)। |
| Carbon dioxide (CO₂) | कार्बन डाइऑक्साइड — वायु की गैस; भोजन बनाने के लिए जरूरी। |
| Oxygen (O₂) | ऑक्सीजन — प्रकाश संश्लेषण में निकलती है; श्वसन में काम आती है। |
| Epidermis | एपिडर्मिस — पत्ती/तने की बाहरी पतली परत; इससे पील निकलकर रंध्र देखे जाते हैं। |
| Germinating seeds | अंकुरित बीज — सक्रिय रूप से श्वसन करते हैं, CO₂ देते हैं। |
| Caustic soda | कॉस्टिक सोडा (NaOH) — CO₂ सोखने के लिए प्रयोग में लिया जाता है। |
| Transport (in plants) | परिवहन — जाइलम/फ्लोएम द्वारा पानी, खनिज और भोजन का घूमना। |
2) Detailed Notes (Simple English, complete chapter)
10.1 How Do Plants Grow?
As plants grow, they show new leaves & branches, increase in height, and thicker stems. Growth needs sunlight, water, minerals, and food made by the plant.
Activity (Pots A, B, C): A = sunlight + water → best growth; B = sunlight, no water → wilts/dies; C = dark + water → weak, pale/yellow, poor growth.
Conclusion: Plants need both sunlight and water for healthy growth.
Conclusion: Plants need both sunlight and water for healthy growth.
10.2 How Do Plants Get Food?
Animals eat food, but plants make their own food. Leaves are the food factories of a plant. They are usually green due to chlorophyll, which captures sunlight.
10.2.1 Leaves make and store food (starch)
Starch (iodine) test on a leaf: Boil leaf → decolourise in alcohol → add iodine. If leaf turns blue-black, starch is present. We decolourise so the colour change is clearly visible.
10.2.1 (b) Role of sunlight & chlorophyll
Variegated leaf test: Take a leaf with green & non-green patches from a plant kept in sunlight and from a plant kept in dark. After iodine test:
- Green parts (with chlorophyll) from sunlight plant → blue-black (starch formed).
- Non-green parts → usually no blue-black (little/no chlorophyll, no detectable starch).
- Leaves from dark plant → no blue-black even in green parts (no starch formed without light).
Colored leaves: Some leaves look red/violet/brown because other pigments hide green. They still have chlorophyll and can photosynthesize; iodine test can still show starch.
10.2.2 Air (CO₂) is required
Bottle experiment: Keep half leaf inside a bottle with caustic soda (absorbs CO₂) and half outside. Place in sunlight. After iodine test:
- Outside half (has CO₂) → blue-black (starch made)
- Inside half (CO₂ removed) → no blue-black (no starch)
10.2.3 Photosynthesis — in a nutshell
In the presence of sunlight and chlorophyll, plants use carbon dioxide (air) and water (roots) to make glucose and release oxygen. Glucose may later be stored as starch.
Carbon dioxide + Water ⟶ Glucose + Oxygen (in sunlight & chlorophyll)
Oxygen release experiment: Water plant under a funnel with an inverted test tube. In sunlight, bubbles collect in the tube. The gas rekindles a glowing match → it is oxygen.
Conclusion: Photosynthesis releases oxygen and needs light.
Conclusion: Photosynthesis releases oxygen and needs light.
Know a Scientist — R. H. Dastur: Studied effects of water, temperature and light colour on photosynthesis in India.
10.2.4 Gas exchange: where does it happen?
Leaf peel under microscope: You can see tiny pores called stomata. They open/close and help exchange of CO₂ and O₂ during photosynthesis and respiration.
Ancient insight — Vṛkṣāyurveda: Early Indian text recorded practical plant-growth ideas like organic manures and careful cultivation—it notes that just planting is not enough; proper care is needed for flowers & fruits.
10.3 Transport in Plants
10.3.1 Water & minerals: Xylem
Red-ink twig experiment: Put a white-flowering twig in colored water. Next day, stem/leaf/flower show red lines. Cutting the stem shows colored tracks → these are xylem.
Conclusion: Xylem carries water & minerals upward from roots to all parts.
Conclusion: Xylem carries water & minerals upward from roots to all parts.
10.3.2 Food: Phloem
Leaves make food (glucose/starch). This food moves to other parts (like roots, fruits, seeds) through phloem. Plants may store food in seeds, roots, stems, or fruits.
10.4 Do Plants Respire?
Yes. All parts (green or non-green) respire day and night. In respiration, glucose breaks down using oxygen to release energy, with carbon dioxide and water produced.
Glucose + Oxygen ⟶ Carbon dioxide + Water + Energy
Germinating seeds & lime water: Soaked seeds in a flask turn connected lime water milky because seeds release CO₂ during respiration.
Conclusion: Plants respire to get energy for growth and activities.
Conclusion: Plants respire to get energy for growth and activities.
Photosynthesis vs Respiration
Photosynthesis: makes food, needs light, takes in CO₂, gives out O₂. Respiration: uses food, happens all the time, takes in O₂, gives out CO₂.
Photosynthesis: makes food, needs light, takes in CO₂, gives out O₂. Respiration: uses food, happens all the time, takes in O₂, gives out CO₂.
Know a Scientist — Kamala Sohonie: Indian biochemist who worked on plant respiration and nutrition; also promoted “Neera”, a nutritious palm drink.
Quick Recap (In a Nutshell)
- Plants need sunlight, water, minerals, CO₂ to grow and make food.
- Leaves (with chlorophyll) are the main site of photosynthesis.
- Iodine test shows starch made in green parts under light.
- Photosynthesis makes glucose and releases oxygen.
- Stomata on leaves exchange gases.
- Xylem transports water & minerals; Phloem transports food.
- Plants also respire (day & night) to release energy from food.
Safety & Good Lab Habits
- Do not heat alcohol directly on flame; use a water bath.
- Caustic soda (NaOH) is corrosive; teacher-only handling with protection.
- Handle blades/glassware carefully; keep work area clean.
Practice Set — Life Processes in Plants (Chapter 10)
All answers included • Simple English • Mobile-friendly
1) One-word Answer Questions (10)
| # | Question | Answer (one word) |
|---|---|---|
| 1 | The process by which green plants make food using sunlight. | Photosynthesis |
| 2 | Green pigment present in leaves. | Chlorophyll |
| 3 | Tiny pores on leaf surface for gas exchange. | Stomata |
| 4 | Tissue that transports water and minerals. | Xylem |
| 5 | Tissue that transports prepared food. | Phloem |
| 6 | Simple sugar first formed in photosynthesis. | Glucose |
| 7 | Blue-black colour with iodine indicates presence of this. | Starch |
| 8 | Gas released during photosynthesis. | Oxygen |
| 9 | Chemical used to absorb CO₂ in the bottle experiment. | NaOH |
| 10 | Keeping a plant in dark to remove stored starch is called. | Destarching |
2) Fill in the Blanks (10)
| # | Statement | Answer |
|---|---|---|
| 1 | Leaves are called the ______ of the plant because they make food. | food factories |
| 2 | In photosynthesis, carbon dioxide is taken in through the ______. | stomata |
| 3 | Water and minerals move upward through ______ tissue. | xylem |
| 4 | Food prepared in leaves is transported by the ______. | phloem |
| 5 | The first carbohydrate formed is ______, later stored as starch. | glucose |
| 6 | On adding iodine to a starch-containing leaf, it turns ______. | blue-black |
| 7 | In a variegated leaf, only the ______ regions give blue-black colour. | green |
| 8 | During photosynthesis, plants release ______ gas. | oxygen |
| 9 | To prove CO₂ is needed for photosynthesis, the bottle contains ______. | NaOH |
| 10 | Opening and closing of stomatal pores is controlled by ______ cells. | guard |
3) True/False with Explanation (10)
| # | Statement | True/False | Why? |
|---|---|---|---|
| 1 | Photosynthesis can occur in complete darkness. | False | Light is essential; chlorophyll uses light to make food. |
| 2 | Non-green parts of a variegated leaf give blue-black iodine colour. | False | They lack/insufficient chlorophyll, so starch is not produced there. |
| 3 | Xylem transports food to all parts of the plant. | False | Xylem carries water & minerals; phloem carries food. |
| 4 | Oxygen is produced during photosynthesis. | True | It is released as a by-product; shown by bubble/rekindling test. |
| 5 | Stomata help in gas exchange. | True | They allow CO₂ in and O₂ out; guard cells regulate them. |
| 6 | Destarched plants kept in dark still give positive iodine test. | False | Stored starch is used up in dark; no blue-black colour. |
| 7 | Phloem transports food only downward. | False | Phloem transport is bidirectional, to wherever food is needed/stored. |
| 8 | Respiration in plants happens only at night. | False | Respiration occurs all the time (day and night). |
| 9 | Red dye reaches petals in the coloured water experiment via xylem. | True | Dye travels with water in xylem vessels to leaves/flowers. |
| 10 | Photosynthesis makes proteins directly from CO₂ and water. | False | Photosynthesis makes glucose; proteins need nitrogen (nitrates). |
4) Very Short Answer Questions (10) — (2–3 lines each)
| # | Question | Answer |
|---|---|---|
| 1 | Define photosynthesis. | It is the process by which green plants use sunlight, chlorophyll, CO₂ and water to make glucose, releasing oxygen as a by-product. |
| 2 | Why are most leaves green? | They contain chlorophyll, a green pigment that traps light energy needed for photosynthesis. |
| 3 | What is the role of stomata? | Stomata are tiny pores that allow CO₂ to enter and O₂ to exit; guard cells open/close them to regulate gas exchange. |
| 4 | Why is the leaf boiled in alcohol in the iodine test? | Alcohol removes the green chlorophyll, decolourising the leaf so the blue-black change with iodine is clearly seen. |
| 5 | What is destarching and why is it needed? | Keeping a plant in dark to use up stored starch. It ensures any new starch seen is due to the current experiment. |
| 6 | Name two raw materials of photosynthesis and their sources. | CO₂ from air via stomata; water from soil via roots and xylem. |
| 7 | What does phloem transport? | Prepared food (mainly sugars) from leaves to growing and storage parts like roots, fruits, seeds. |
| 8 | What happens to a plant kept in dark but watered? | It survives for some time using stored food, becomes pale/yellow, grows poorly, and forms no new starch. |
| 9 | Write the word equation for respiration in plants. | Glucose + Oxygen ⟶ Carbon dioxide + Water + Energy. |
| 10 | Why do germinating seeds turn lime water milky? | They respire actively and release CO₂, which reacts with lime water to form milky calcium carbonate. |
5) Short Answer Questions (10) — (3–4 lines each)
| # | Question | Answer |
|---|---|---|
| 1 | Describe an activity to show oxygen is released during photosynthesis. | Place a water plant under a funnel with an inverted test tube filled with water. Keep in sunlight. Bubbles collect in the tube; the gas rekindles a glowing splint, proving it is oxygen released during photosynthesis. |
| 2 | How does the variegated leaf experiment prove the role of chlorophyll? | Only green (chlorophyll-containing) regions turn blue-black with iodine after sunlight exposure. Non-green regions do not, showing starch forms only where chlorophyll is present. |
| 3 | Explain transport of water and minerals with the coloured water demo. | Putting a cut twig in coloured water shows red/blue lines in stem, leaves, and flowers next day. The dye moves with water in xylem vessels upward from roots to aerial parts. |
| 4 | Differentiate between photosynthesis and respiration (any three points). | Photosynthesis makes food, needs light, takes in CO₂ and gives out O₂. Respiration uses food, occurs day & night, takes in O₂ and gives out CO₂ to release energy. |
| 5 | How do stomata and guard cells regulate gas exchange? | Guard cells swell (turgid) to open stomata allowing CO₂ in and O₂ out; they shrink (flaccid) to close pores, reducing water loss and controlling gas exchange. |
| 6 | Why do plants store food as starch rather than glucose? | Starch is insoluble, compact, and does not disturb cell water balance, making it safer for storage; glucose is soluble and would affect osmotic conditions. |
| 7 | How does the NaOH bottle setup prove CO₂ is needed? | Half a destarched leaf is placed inside a bottle with NaOH (absorbs CO₂). After sunlight exposure, only the outside half (with CO₂) gives blue-black with iodine. Inside half remains negative, proving CO₂ is essential. |
| 8 | Describe the path of food transport in plants. | Food made in leaves (sources) is loaded into phloem and translocated to sinks (growing roots, fruits, seeds, storage tissues). Movement can be upward or downward as needed. |
| 9 | What did the Pot A/B/C activity teach about growth factors? | Pot A (sunlight + water) grew best; Pot B (sunlight, no water) wilted; Pot C (dark + water) grew poorly and yellowed. Both sunlight and water are essential for healthy growth. |
| 10 | Why do plants still need respiration if they make food by photosynthesis? | Photosynthesis makes glucose; respiration breaks it down to release usable energy for growth, repair, transport, and other life processes, all day and night. |
Tip: Practise drawing neat, labelled diagrams of a leaf with stomata, and xylem-phloem in a stem cross-section.