NCERT Class 7 Science Curiosity Chapter 10 Life Processes in Plants PDF Download

Chapter 10: Life Processes in Plants

In Grade 6, we learnt that all living beings grow and need food for their growth. Also, in the previous chapter, we discussed the process through which animals obtain nutrition.

We know that animals eat food to grow, but what about plants? Have you ever seen plants eating food like animals do? As animals grow, their size and weight usually increase, and their bodies undergo various changes. What changes do you notice in plants when they grow?

We learnt that food provides nutrients like carbohydrates, fats, proteins, vitamins, and minerals, which, along with water, are all essential for growth. Let us explore how plants obtain nutrients for their growth.

10.1 How Do Plants Grow?

Look around your neighbourhood. Have you observed any changes in a plant during its life span? As a plant grows, new leaves and branches emerge, its height increases, and its stem thickens. What do you think causes these changes? Discuss with your friends and provide your explanation as well.

Let us perform an experiment to test some of these explanations.

Activity 10.1: Let us test some explanations

• Take three earthen pots (or used bottles/containers) of the same size filled with garden soil. Plant saplings of similar sizes of a fast-growing plant like chilli or tomato in each pot (Fig. 10.1).
• Label the pots A, B, and C.
• Count the number of leaves on each sapling and record your observations.
• Place pot A in direct sunlight. Keep the soil in this pot slightly moist by adding an adequate amount of water every day (Fig. 10.1a).
• Place pot B in direct sunlight, without adding water to the soil (Fig. 10.1b).
• Place pot C in the dark. Keep the soil in this pot slightly moist by adding an adequate amount of water every day (Fig. 10.1c).
• Observe the plants for two weeks and record changes in their height, number of leaves, colour of leaves, and any other changes that may appear.
• Record your observations in Table 10.1.

[Figure 10.1: Experimental set-up to understand the role of sunlight and water in plant growth, See in your textbook]

• What differences did you observe between the plants in the three pots?
• Which pot has the plant with the maximum growth?
• Which pot has the plant with the least growth?

Analyse the observations recorded in Table 10.1, and discuss them with your teacher and friends.

Teacher's Note

When you set up this experiment, remember that pot A is your control - it has both sunlight and water. By comparing pots B and C to pot A, you can figure out what each factor does separately. Don't just look at which plant grew most; think about which variable (sunlight or water) caused each difference you see.

You are likely to find that the plant in Pot A, kept in direct sunlight with adequate water, grows better than the plant in Pot C, which gets adequate water but no sunlight. The plant in Pot B may have died as it did not get water even though it received adequate sunlight.

What do you infer from the observations made in this activity? The results indicate that plants require both sunlight and water for their growth.

Teacher's Note

Notice that neither sunlight alone nor water alone is enough - the plant in pot B (sunlight but no water) likely died. Plants need both factors to survive and grow. In exams, always explain why each condition matters by referring back to what you observed in each pot.

Key Points

• Plants grow by producing new leaves and branches, increasing in height, and thickening their stems.
• Both sunlight and water are essential for plant growth; if either is missing, plants cannot grow properly.
• Plants obtain nutrients and other requirements for growth from water, soil, and energy from sunlight.
• In experiments, comparing plants under different conditions helps you understand which factors are necessary for growth.

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