Life Processes In Plants

So students, welcome to today's science lesson. I am so happy to see you all here, ready to learn something new and exciting about the world around us. Today, we are going to study Chapter 10 from your Science textbook, and the title is "Life Processes in Plants". This is a fascinating chapter because it will tell us how plants live, how they grow, and how they get their food. You know, we often think that animals are the ones who need food to grow, but have you ever wondered about plants? Do they also need food? How do they get it? Let's find out together.

So students, let's start by recalling what we learned 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 also learnt that food provides nutrients like carbohydrates, fats, proteins, vitamins, and minerals, which, along with water, are all essential for growth. Now let us explore how plants obtain nutrients for their growth.

So students, let's begin with the first section of our chapter, which is titled "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? Think about this for a moment. When we water plants regularly, they grow better. So, water must contribute to its growth. Maybe plants take up food from the soil through their roots. I think sunlight plays some role in the growth of plants. There could be many factors at play here.

Now, let us perform an experiment to test some of these explanations. This is Activity 10.1 in your textbook.

So students, in this activity, we are going to take three earthen pots, or you can even use used bottles or containers, of the same size and fill them with garden soil. We need to plant saplings of similar sizes of a fast-growing plant like chilli or tomato in each pot. Now, label the pots as A, B, and C. Count the number of leaves on each sapling and record your observations.

Now, here is what we are going to do with each pot. Place pot A in direct sunlight. Keep the soil in this pot slightly moist by adding an adequate amount of water every day. This is our control pot with both sunlight and water. Place pot B in direct sunlight, but without adding water to the soil. This will help us understand what happens when there is no water. Place pot C in the dark, meaning in a place where there is no sunlight, but keep the soil in this pot slightly moist by adding an adequate amount of water every day. This will help us understand what happens when there is no sunlight.

Now, 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, which is given in your textbook.

After two weeks, 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?

Let me tell you what we generally observe in such an experiment. 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.

So students, what do we infer from the observations made in this activity? The results indicate that plants require both sunlight and water for their growth. This is a very important finding, and we will explore this further in our chapter.

Now, before we move on, let me tell you something fascinating. There is an ancient Indian text named Vrikshayurveda, which means the science of plant life. It contains a beautiful line that says, "Trees do not produce fruits and flowers merely because they are planted." This text records useful observations about plant growth, soil, and agricultural practices to help improve crop health, growth and production. The knowledge in the text seems to be based on practical experiences and patterns seen over time. These ideas were then systematically documented to guide farming practices. For instance, there are references to different methods of organic manure preparation, such as mixing water, barley, and various seeds, like green, black, and horse grams. Isn't that wonderful, students? Our ancestors were so observant and wise!

Now, let's move on to the next section, which is "How Do Plants Get Food for their Growth?"

We know that animals get their food from plants, either directly by eating plants or indirectly by eating animals that in turn eat plants for their nutrition and growth. But how do plants obtain the food they need to grow? Unlike animals, plants do not eat food. So how do they get their food? This is what we are going to learn now.

So students, let's understand the role of leaves in food preparation. Leaves are often called the 'food factories' of plants. Let me explain why.

Plants store food in the form of starch, a type of carbohydrate. This starch is produced in the leaves of a plant which, by design, are generally broad and flat. These are mostly green because of the presence of a green pigment called chlorophyll, that helps in capturing sunlight efficiently.

Now, let us find out the role chlorophyll plays in the preparation of food in the form of starch in plants. This is Activity 10.2 in your textbook.

In this activity, the teacher may demonstrate the following steps. First, keep a leaf in boiling water for five minutes to soften it. Then, dip this leaf in a test tube containing alcohol. Place the test tube in a beaker containing boiling water. Wait until the leaf becomes colourless. This process is called decolourisation. Then, take out the leaf and place it on a plate. Now, put a few drops of diluted iodine solution with the help of a dropper on the decolourised leaf. Wait for a few minutes and observe. If the colour of the leaf changes to blue-black, it indicates the presence of starch.

Now, students, you might wonder why we decolourise the leaf in the beginning of this activity. The answer is simple: decolourisation of a leaf enables us to easily observe colour change and, thus, the presence of starch. If we didn't remove the green colour, we wouldn't be able to see the blue-black colour clearly when iodine reacts with starch.

So students, in Activity 10.1, we have learnt that water and sunlight are essential for plant growth. In Activity 10.2, we have discovered that green leaves store starch as food. Now, let me tell you about a curious student named Bhaskar who loves gardening. He often looks around his garden and wonders how plants produce food. From his experiences, Bhaskar knows that water and sunlight are essential for plant growth. But he wonders if sunlight contributes to the production of food in the form of starch in plants. How does sunlight contribute in the production of starch in plants?

Let's find out through Activity 10.3.

Bhaskar took a leaf having both green and non-green patches from each of two similar potted plants—one kept in sunlight and the other kept in the dark for 36 hours. He wanted to compare the leaves before and after the starch test.

He made a sketch of the leaves to record the location of the green and the non-green patches on them with the help of a tracing paper. After that, he performed the iodine test on the leaves. Bhaskar recorded his observations in Table 10.2.

Now, let's look at what Bhaskar observed. In Table 10.2, Bhaskar recorded a blue-black colour, indicating the presence of starch, on the green patches of the leaf obtained from the plant placed in sunlight. Bhaskar also recorded that the leaf obtained from the plant kept in the dark does not show a blue-black colour, even on the green patches, indicating that no starch has been produced. Non-green patches of the leaf obtained from the plant placed in sunlight do not turn blue-black. Does it indicate that there is no chlorophyll present in those patches? The non-green patches may not have sufficient chlorophyll to prepare enough starch to be detected using the iodine test.

So students, what do we infer from the observations listed in Table 10.2? As we know, leaves are mostly green because of the presence of chlorophyll. We have also seen that the starch is produced where green patches of the leaf are present. We can infer that chlorophyll helps in preparing starch in the presence of sunlight. In fact, it is essential for the preparation of starch. Hence, the leaves are also called 'food factories' of plants.

Now, students, what else is essential for the preparation of food in plants? Let us find out.

While reading about contributions of scientists in plant nutrition, my sister told me that air plays a role in the process of food preparation in plants. Which gas from the air is essential in the process of food preparation in plants?

Let's find out through Activity 10.4.

In this demonstration activity, the teacher may perform the following steps. Take a potted green plant and keep it in the dark for two to three days to allow it to destarch, that is, lose any stored starch. Then, locate one leaf of this plant for this experiment.

Take a wide-mouthed bottle and pour some caustic soda, which is sodium hydroxide, into it. Remember, caustic soda absorbs carbon dioxide from the air. Now, insert half of the destarched leaf into the bottle through a split cork, leaving the other half of the leaf outside, and place the bottle as shown in Figure 10.3a in your textbook.

Place the set-up in sunlight for a few hours. Observe and record the availability of water, sunlight, chlorophyll, and carbon dioxide in Table 10.3. Remove the leaf and test it for starch using the iodine test, as was done in Activity 10.2. Record your observations in Table 10.3.

Now students, what do we notice? The part of the leaf that was outside the bottle turns blue-black, indicating the presence of starch. However, the part of the leaf inside the bottle does not turn blue-black in colour, indicating that food is not made in that part of the leaf. This is because the caustic soda solution inside the flask absorbs the carbon dioxide present in the air. What does this experiment show? This experiment shows that carbon dioxide present in the air is essential for plants to prepare starch.

So students, based on Activities 10.3 and 10.4, what do we conclude? Which part of the plant is involved in the synthesis of starch?

Based on our learnings so far, we have found that sunlight, water, chlorophyll, and carbon dioxide are essential for the synthesis of food in plants. This process by which plants prepare food in the presence of sunlight and chlorophyll is called photosynthesis. A leaf is the primary site for photosynthesis. Do other green parts of the plant also perform photosynthesis? Yes, other parts of the plants which have chlorophyll also perform photosynthesis.

Now students, let me tell you something interesting. Some plant leaves appear red, violet, or brown because they contain more of these coloured pigments than the green-coloured chlorophyll. This hides the green colour. Some of these pigments also help in photosynthesis. You can use an iodine test to check for the presence of starch in these leaves, indicating that photosynthesis has indeed taken place.

So far, we have learnt that plants take in carbon dioxide from the air and water, and use sunlight to prepare their food by the process of photosynthesis. But have you ever thought about what more happens during this process? Do plants only take in substances from their surroundings, or do they also release something? Let us explore this through an experiment performed by Barkha didi.

In Activity 10.5, we are going to explore what happens during photosynthesis. Look at Figure 10.4 in your textbook. Compare the two set-ups labelled as A and B, and analyse. In Figure 10.4, set-up A is placed in sunlight, and set-up B is placed in the dark. What difference do you observe in the two set-ups? Do you observe air bubbles emerging in the inverted test tube in set-up A? The gas produced in this set-up caused bubbles to emerge and get accumulated in the inverted test tube. Which gas is this?

Oh yes! I remember. In our science lab, I have seen a similar set-up placed under sunlight near a window.

When sufficient gas was accumulated in the inverted test tube, Barkha didi placed her thumb on the mouth of the test tube while taking the test tube off the set-up. She then quickly inserted a lit matchstick into the tube and the matchstick produced an intense flame.

She inferred that the gas in the test tube is rich in oxygen. It indicates that oxygen is released during the process of photosynthesis. It also indicates that photosynthesis occurs in the presence of sunlight.

So students, based on Barkha didi's experiment, we can conclude that oxygen is released during photosynthesis.

Now let's summarise what we have learnt about photosynthesis in section 10.2.3.

We know that water, sunlight, carbon dioxide from the air, and chlorophyll are necessary to carry out the process of photosynthesis that produces carbohydrates. During photosynthesis, food is actually produced in the form of glucose, a simple carbohydrate. This glucose not only serves as an instant source of energy but also later gets converted into starch for storage. The word equation of photosynthesis is given below.

Carbon dioxide plus water, in the presence of sunlight and chlorophyll, gets converted into glucose plus oxygen.

So students, let's write this down clearly. The raw materials for photosynthesis are carbon dioxide and water. The products are glucose and oxygen. This process takes place in the presence of sunlight and chlorophyll.

Now, I want to tell you about an Indian scientist who contributed to the understanding of photosynthesis. His name is Rustom Hormusji Dastur, and he lived from 1896 to 1961. He was a plant scientist and served as the head of the Botany Department at the Royal Institute of Science, Bombay, which is now the Institute of Science, Mumbai, from 1921 to 1935. He studied effects of the amount of water and temperature on photosynthesis. He examined the importance of water, temperature, and the colour of light in the process of photosynthesis. This shows that Indian scientists have also made significant contributions to the field of plant science.

Now, let's move on to section 10.2.4: How do leaves exchange gases during photosynthesis?

We now know that photosynthesis requires carbon dioxide, and oxygen is released in the process. Which part of the plant helps in the exchange of carbon dioxide and oxygen? Let us conduct an activity to understand where the exchange of gases takes place.

This is Activity 10.6, which is a demonstration activity.

In this activity, the teacher may demonstrate the following steps. Collect a leaf from a plant such as rhoeo, money plant, onion, hibiscus, coleus, or any grass. Put it in a beaker filled with water. Carefully peel a thin layer from the lower surface of the leaf. Place the peel in a watch glass with water. Now, take a microscope slide and carefully put a drop of water on it. Using forceps, transfer the peel of the leaf from the watch glass to the slide with the help of forceps. Put a drop of ink on the leaf peel with the help of a dropper. Cover the peel with a coverslip and observe it under a microscope.

What do you observe? Do you notice tiny pores on the peel, as shown in Figure 10.6? These pores are called stomata. Stomata, present on the surface of leaves, help in the exchange of gases.

So students, now we understand that stomata are the tiny pores on the surface of leaves that help in the exchange of oxygen and carbon dioxide during photosynthesis and respiration.

Now, let's move on to the next major section of our chapter, which is "Transport in Plants".

All living beings need water to grow. Plants use water in the process of photosynthesis. Water, along with minerals present in the soil, is taken up by the roots of a plant. Minerals are important nutrients for the growth of plants. How do water and minerals taken up by the roots move to all parts of the plant?

We can study water transport in plants by carrying out an activity. For this activity, we require two glass tumblers, some water, red ink, and twigs of two similar tender plants, preferably with white-coloured flowers, for example, white sadabahar or balsam.

This is Activity 10.7.

In this activity, take two tumblers and label them A and B. Fill one-third of each tumbler with water. Add a few drops of red ink to tumbler B. Obliquely cut the stems of both plants at their base while keeping them inside the water and immediately place one plant in each tumbler, as shown in Figure 10.7a and Figure 10.7b. Observe these plants the next day.

What do you notice? Compare the plant stems placed in the tumblers. Do you observe red colour in the stem, leaves, and flowers of the plant from Tumbler B? Figure 10.7c and Figure 10.7d show the plants after one day. Compare the plant in Figure 10.7c with that in Figure 10.7d. A red colour is visible in the stem, leaves, and flowers of the plant in Figure 10.7d. How did different parts of the plant acquire this red colour?

Cut the stem from the upper part of the plant that is not immersed in the red-coloured water. Observe the cut stem using a magnifying glass. Do you spot the red colour in the stem?

How does the red colour ink move upwards? This is due to the thin tube-like structure called the xylem present in the stem, branches, and leaves of plants. Just like red ink, minerals dissolved in water also move up the stem through the xylem.

So students, now we know that water and minerals are transported to the leaves and other parts of plants through the xylem. The water transported through the xylem is used to perform various functions.

Now, how does food get transported to other parts of a plant? We know that leaves are the primary site for photosynthesis. The food prepared by plants in the leaves is transported to all parts of the plant. This food is transported through another set of thin tube-like structures called the phloem. The transported food may also be stored in some other parts of a plant, such as seeds and roots.

So students, let's recap what we have learned about transport in plants. The xylem transports water and minerals from roots to all parts of the plant, while the phloem carries food from leaves to all parts of the plants.

Now, let's move on to the last section of our chapter, which is "Do Plants Respire?"

In the Grade 6 Science textbook Curiosity, chapter 'Living Creatures: Exploring their Characteristics', you learnt that all living beings respire. Do plants also respire like we do? Let's find out.

This is Activity 10.8, which is a demonstration activity.

In this activity, soak some moong bean seeds in water overnight. Put a layer of cotton in a conical flask and moisten the cotton with water to keep it wet. Place the soaked seeds over the wet cotton in the conical flask. Cover the mouth of the conical flask with a cork having two holes. Fit two tubes A and B through the two holes on the cork, as shown in Figure 10.9. Leave it undisturbed for 24 hours in the dark.

Take two test tubes and fill them with lime water. Cover the mouth of one test tube with a cork having one hole in it. Dip one glass tube in the test tube through a hole in the cork. Connect the flask and test tube with a rubber pipe as shown in Figure 10.9.

Compare both the test tubes for any change in colour. Does the lime water turn milky in both the test tubes? Why does the lime water turn milky in the test tube connected to the flask? Lime water turns milky due to the presence of more carbon dioxide in the flask. But where does this carbon dioxide come from? As we know, carbon dioxide is naturally present in very small quantities in the air. In the flask, additional carbon dioxide is produced by the seeds as they respire.

During respiration, glucose is broken down in the presence of oxygen, releasing carbon dioxide, water, and energy. The word equation for the process of respiration is as follows.

Glucose plus oxygen gets converted into carbon dioxide plus water plus energy.

The energy produced during respiration is used by plants for their growth and development. All parts of a plant, green or non-green, carry out respiration.

Thus, plants have different mechanisms for synthesising, transporting, and utilising food to get energy.

Now students, let me give you a summary of the entire chapter in "In a Nutshell" section.

All living organisms require food that provide energy for their growth and development. Plants use carbon dioxide and water in the presence of sunlight and chlorophyll to produce glucose and oxygen. This process of synthesis of food is known as photosynthesis. Leaves are the 'food factories' of a plant. Tiny pores on the surface of leaves, called stomata, help in the exchange of oxygen and carbon dioxide during photosynthesis and respiration. The xylem transports water and minerals from roots, while the phloem carries food from leaves to all parts of the plants. Plants break down glucose and release energy by a process called respiration. They use oxygen and release carbon dioxide in this process.

Now students, let's look at the exercises in the "Let Us Enhance Our Learning" section and solve them one by one.

Question 1 says: Complete the following table.

We need to compare photosynthesis and respiration. Let me help you fill this table.

For photosynthesis, the raw materials are carbon dioxide and water. The products are glucose and oxygen. The word equation is: Carbon dioxide plus water, in the presence of sunlight and chlorophyll, gets converted into glucose plus oxygen. The importance of photosynthesis is that it produces food for plants and releases oxygen which is essential for most living beings.

For respiration, the raw materials are glucose and oxygen. The products are carbon dioxide, water, and energy. The word equation is: Glucose plus oxygen gets converted into carbon dioxide plus water plus energy. The importance of respiration is that it releases energy which is used by plants for their growth and various metabolic activities.

Now, let's look at Question 2. 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 organisms that carry out photosynthesis disappeared, there would be no oxygen released into the atmosphere. All animals and humans would not be able to breathe. Also, there would be no food produced for herbivores, and subsequently, carnivores would also die. The entire food chain would collapse, and life on Earth would not be possible.

Question 3: 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 food synthesised in the leaves of the potato plant. The food is synthesised in the leaves through the process of photosynthesis. This food, in the form of glucose, is then transported through the phloem to all parts of the plant, including the potatoes, where it is stored as starch.

Question 4: 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 makes plants more efficient for photosynthesis. This is because a broad and flat leaf has a larger surface area to absorb sunlight and carbon dioxide. More chlorophyll is present in such leaves, which helps in capturing more sunlight. The flat surface also allows easy diffusion of gases through stomata.

Question 5: X is broken down using Y to release carbon dioxide, Z, and energy.

X plus Y gets converted into carbon dioxide plus Z plus energy.

X, Y, and Z are three different components of the process. What do X, Y, and Z stand for?

This question is about respiration. X is glucose, Y is oxygen, and Z is water. So the equation is: Glucose plus oxygen gets converted into carbon dioxide plus water plus energy.

Question 6: Krishna set-up an experiment with two potted plants of same size and placed one of them in sunlight and the other in a dark room, as shown in Figure 10.10.

Answer the following questions.

(i) What idea might she be testing through this experiment?

Krishna might be testing the idea that sunlight is essential for photosynthesis, which produces starch in plants.

(ii) What are the visible differences in plants in both the conditions?

The plant kept in sunlight will have green leaves, will grow well, and will show the presence of starch in the iodine test. The plant kept in the dark will have yellow leaves, will not grow well, and will not show the presence of starch.

(iii) According to you, leaves of which plants confirm the iodine test for the presence of starch?

(a) Sunlight - Yes, the leaves kept in sunlight will show a positive iodine test, meaning they will turn blue-black, indicating the presence of starch.

(b) Complete dark - No, the leaves kept in complete dark will not show a positive iodine test, meaning they will not turn blue-black, indicating the absence of starch.

Question 7: Vani believes that 'carbon dioxide is essential for photosynthesis'. She puts an experimental set-up, as shown in Figure 10.11, to collect evidence to support or reject her idea.

The set-up has four conditions: (a) Sunlight with carbon dioxide, (b) Sunlight without carbon dioxide, (c) Dark with carbon dioxide, (d) Dark without carbon dioxide.

Answer the following questions.

(i) In which plant(s) in the above set-up(s) will starch be formed?

Starch will be formed only in plant (a), which is in sunlight with carbon dioxide. This is because both sunlight and carbon dioxide are essential for photosynthesis.

(ii) In which plant(s) in the above set-up(s) will starch not be formed?

Starch will not be formed in plants (b), (c), and (d). In (b), there is no carbon dioxide. In (c), there is no sunlight. In (d), there is neither sunlight nor carbon dioxide.

(iii) In which plant(s) in the above set-up(s) will oxygen be generated?

Oxygen will be generated only in plant (a), which is in sunlight with carbon dioxide, because photosynthesis occurs only under these conditions.

(iv) In which plant(s) in the above set-up(s) will oxygen not be generated?

Oxygen will not be generated in plants (b), (c), and (d) for the same reasons as mentioned above.

Question 8: Ananya took four test tubes and filled three-fourth of each test tube with water. She labelled them A, B, C, and D. In test tube A, she kept a snail; in test tube B, she kept a water plant; in test tube C, she kept both a snail and a plant. In test tube D, she kept only water. Ananya added a carbon dioxide indicator to all the test tubes. She recorded the initial colour of water and observed if there are any colour changes in the test tubes after 2–3 hours.

What do you think she wants to find out? How will she know if she is correct?

Ananya wants to find out how carbon dioxide levels change in the presence of a snail, a plant, or both. A carbon dioxide indicator changes colour based on the amount of carbon dioxide present. In test tube A with a snail, the carbon dioxide level will increase because the snail respires and releases carbon dioxide. In test tube B with a water plant, the carbon dioxide level will decrease because the plant uses carbon dioxide for photosynthesis. In test tube C with both a snail and a plant, the carbon dioxide level may remain balanced because the plant uses the carbon dioxide released by the snail. In test tube D with only water, there will be no significant change. She will know she is correct by observing the colour changes in the carbon dioxide indicator in each test tube.

Question 9: Design an experiment to observe if water transportation in plants is quicker in warm or cold conditions.

To design this experiment, we can take two similar plants or cut stems of the same plant. Place one in a glass of water with red ink and keep it in a warm place, perhaps near a window with sunlight. Place the other in a glass of water with red ink and keep it in a cold place, such as a refrigerator or a cool room. After a few hours, observe which plant shows the red colour moving up faster. The plant in the warm place should show faster water transportation because heat increases the rate of transpiration and movement of water through the xylem.

Question 10: Photosynthesis and respiration are essential to maintain balance in nature. Discuss.

Photosynthesis and respiration are two opposite processes that help maintain balance in nature. During photosynthesis, plants take in carbon dioxide and release oxygen, which is essential for animals and humans to breathe. During respiration, animals and plants take in oxygen and release carbon dioxide, which is used by plants for photosynthesis. This creates a cycle where carbon dioxide and oxygen are continuously recycled. Without this balance, life on Earth would not be possible.

Now students, let's look at the "Exploratory Projects" section.

The first project is to develop a bottle garden by planting a growing plant like spider plant or jade plant in a large transparent bottle. After growing the plant properly for some time, seal the mouth of the bottle. Observe the growth of the plant. If the plant is growing well, that means the plant is maintaining the exchange of gases, that is, carbon dioxide produced in the process of respiration of the plant is utilised for performing photosynthesis, and oxygen generated in photosynthesis is utilised in respiration by the plant inside the bottle. This is a wonderful experiment that shows how plants and animals can live together in a balanced environment.

The second project asks: How are plant processes like photosynthesis, respiration, and water and food transportation crucial for crop production?

This is an important question for farmers. Photosynthesis is crucial because it helps crops produce food, which determines the yield. Respiration is important because it provides energy for plant growth. Water and food transportation ensure that all parts of the plant get the nutrients they need. Without these processes, crops would not grow properly, and farmers would not get a good harvest.

The third project is to visit a greenhouse, if there is one near your place. Observe how people grow plants in a greenhouse. Find out how they regulate the amount of light, water, and carbon dioxide used to grow plants. This is a great way to learn about modern agricultural practices.

Now, students, I want to tell you about a remarkable Indian woman scientist named Kamala Sohonie, who lived from 1911 to 1998. She was a woman scientist of India. She received a Ph.D. degree for her remarkable contribution in the area of respiration in plants from Cambridge University. She returned to India and worked at the Lady Hardinge Medical College in New Delhi, and later at the Nutrition Research Laboratory, Coonoor. Thereafter, she moved to the then Royal Institute of Science, Bombay, where she was eventually appointed as Director. Much of her work helped improve the nutritive values of plant foods. She also worked on the sap of the coconut palm as a nutritive drink called Neera. She was an inspiration for many young scientists in India.

Now students, we have come to the end of our lesson. Let me give you a complete summary of everything we have learned in this chapter.

In this chapter, we learned about the life processes in plants. We started by understanding how plants grow. We performed an experiment to show that plants require both sunlight and water for their growth. Then, we learned how plants get their food. We discovered that leaves are the food factories of plants because they produce food through photosynthesis. We learned that chlorophyll, which gives leaves their green colour, helps in capturing sunlight. We performed activities to show that sunlight, water, carbon dioxide, and chlorophyll are all essential for photosynthesis. We also learned that oxygen is released during photosynthesis.

We then learned about the stomata, which are tiny pores on the surface of leaves that help in the exchange of gases.

After that, we learned about transport in plants. We discovered that water and minerals are transported from roots to all parts of the plant through the xylem, while food is transported from leaves to all parts of the plant through the phloem.

Finally, we learned that plants also respire, just like animals. During respiration, glucose is broken down in the presence of oxygen to release carbon dioxide, water, and energy. This energy is used by plants for their growth and development.

We also solved all the exercises in the chapter, which helped us understand the concepts better. We learned about the differences between photosynthesis and respiration, and how they are both essential for life on Earth.

So students, this is the end of our lesson on Chapter 10: Life Processes in Plants. I hope you have understood all the concepts clearly. Remember, plants are just as alive as animals and humans, and they too need food, water, and air to survive. They have their own way of obtaining nutrition and producing energy. It is important to appreciate and protect our plants because they provide us with food, oxygen, and many other resources.

Thank you for listening so attentively. Keep learning, keep exploring, and never stop being curious about the world around you. See you in the next lesson!