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๐ฌ Think about it
Look at a plant in your neighbourhood. Over weeks it gets taller, grows new leaves, and its stem thickens. What makes a plant grow like this? Let us test sunlight and water and find out.
What changes happen when a plant grows?
- New leaves and branches come out of the plant.
- Its height increases over time.
- Its stem becomes thicker.
- Plants need food and water for this growth.
Example:
A small tomato sapling slowly becomes a tall, leafy plant over a few weeks.
In this Activity, we will test whether sunlight and water are needed for a plant to grow.
Materials needed
Three earthen pots (or used bottles) of the same size, garden soil, and saplings of a fast-growing plant like chilli or tomato.
Procedure
1. Fill three same-size pots with garden soil and plant similar saplings.
2. Label the pots A, B, and C.
3. Count the leaves on each sapling and record them.
4. Place pot A in direct sunlight and water it daily.
5. Place pot B in direct sunlight, without adding water.
6. Place pot C in the dark and water it daily.
7. Observe for two weeks and record changes in Table 10.1.
2. Label the pots A, B, and C.
3. Count the leaves on each sapling and record them.
4. Place pot A in direct sunlight and water it daily.
5. Place pot B in direct sunlight, without adding water.
6. Place pot C in the dark and water it daily.
7. Observe for two weeks and record changes in Table 10.1.
Table 10.1 — Effect of sunlight and water on plant growth
| Pots kept under different conditions | Availability of | Height of plant (cm) | Number of leaves | Colour of leaves (Green/Yellow) | |||
|---|---|---|---|---|---|---|---|
| Sunlight | Water | Day 1 | After 2 weeks | Day 1 | After 2 weeks | ||
| Pot A: In direct sunlight, with water | Yes | Yes | 6 | 14 | 5 | 11 | Green |
| Pot B: In direct sunlight, without water | Yes | No | 6 | Plant died | 5 | 0 | Yellow |
| Pot C: In the dark, with water | No | Yes | 6 | 9 | 5 | 6 | Yellow |
Observation
The plant in Pot A grows best. The plant in Pot C grows poorly with pale leaves. The plant in Pot B may die without water.
Explanation
Pot A had both sunlight and water, so it grew well. Pot C lacked sunlight and Pot B lacked water. So plants need both sunlight and water to grow.
โ Summary
- Three pots, different conditions
- Pot A grew best
- No water, plant died
- Sunlight and water needed
๐ฟ Fascinating Facts
- "Trees do not produce fruits and flowers merely because they are planted."
- This line is from an ancient Indian text named Vrikshayurveda.
- It records useful observations about plant growth, soil, and farming.
- It even describes ways to make organic manure from water, barley, and grams.
Important Points
- Growing plants gain height, leaves, branches, and thickness.
- Plants need both sunlight and water to grow.
- Plants do not eat food the way animals do.
โ Test Yourself
-
What changes happen when a plant grows?
View Answer
New leaves and branches come out, height increases, and the stem thickens. -
Which two things did Activity 10.1 test?
View Answer
The roles of sunlight and water in plant growth. -
Which pot grew the best?
View Answer
Pot A, kept in sunlight with water. -
Why did the plant in Pot B die?
View Answer
It got sunlight but no water. -
Why did the plant in Pot C grow poorly?
View Answer
It was kept in the dark, with no sunlight.
Important Definitions
- Growth in Plants — the increase in a plant's height, leaves, branches, and thickness over time.
