1. Nutrition in Plants

Plant Cell

Diagram:

Features:

1. All living organisms are made of tiny microscopic units called cells. 
2. A cell is surrounded & protected by a boundary called cell wall. 
3. Inside the cell wall, is a thin outer boundary of the cell called the cell membrane.
4. Each cell has a distinct, centrally located spherical structure called the nucleus.
5. The nucleus is surrounded by a jelly-like substance called cytoplasm. It gives shape to the cells.
6. Chloroplast is an green organelle in the plant cell which contains chlorophyll where photosynthesis takes place.
7. Unicellular organisms are made of only one cell.
8. Multicellular organisms are made up of many cells.

To remember:

1. Cell is the basic unit of all living organisms.
2. It contains chloroplasts where photosynthesis takes place.

Photosynthesis:

Definition:

The process by which green plants prepare their own food in the presence of sunlight is called as photosynthesis.

Diagram:

Process:

1. The chloroplasts in leaves of green plants contain a green pigment called chlorophyll.
2. Chlorophyll in the presence of sunlight, uses carbon dioxide from air & water to synthesize (prepare) food i.e. carbohydrate (glucose).
3. During this process oxygen is released.
4. The carbohydrate is supplied to all the parts of the plant.
5. In this process, light energy is converted into chemical energy.

Other features:

1. It takes place in other green parts of the plant, like green stems & branches.
2. Desert plants have green stems to carry out photosynthesis.

Equation:

Importance:

1. Photosynthesis is the primary means to convert solar energy is into chemical energy, forming the base of most food chains.
2. Thus survival of almost all living organisms directly or indirectly depends upon the food made by the plants. 
3. Photosynthesis releases oxygen into the atmosphere which is essential for the survival.
4. It plays maintains the balance of carbon dioxide & oxygen​ in the atmosphere.
5. In the absence of photosynthesis there would not be any food & life would be impossible on the Earth.

To remember:

1. Process of preparation of food by plants is called as photosynthesis.
2. Photosynthesis is carried on by the chlorophyll in presence of sunlight.
3. Chlorophyll prepares carbohydrates from carbon dioxide & water.
4. In this process, oxygen is released in the atmosphere.
5. Thus, photosynthesis sustains life on Earth by providing food & oxygen while regulating the environment.

Role of leaves in photosynthesis:

1. Leaves are the food factories of the plants.
2. Thus, all the raw materials for photosynthesis must reach the leaf.

Supply of water & minerals:

1. Water & minerals present in the soil & absorbed by the roots.
2. The plants have pipe like vessels present throughout the root, stem, branches & leaves.
3. This continuous vascular system helps water, minerals & nutrients to reach the leaf.

Stomata:

1. The surface of the leaves have tiny pores called as stomata.
2. The stomata takes in carbon dioxide from air for photosynthesis.
3. It releases oxygen into the sir after photosynthesis.
4. Thus, exchange of gases takes place through stomata.
5. The stomata is surrounded by guard cells.
6. Guard cells regulate the opening & closing of the stomata.

Chlorophyll:

1. The leaf cells contain a green organelle called chloroplasts.
2. Chloroplast contains the green pigment called chlorophyll.
3. Chlorophyll helps the leaves to capture the energy of the sunlight.
4. This is where the process of photosynthesis takes place.
5. Some leaves that are not green also have chlorophyll & can prepare their own food.
6. The large amount of red, brown & other pigments mask the green colour.

Diagram:

Transpiration in leaves:

1. The process though which plants release water in the form of vapour in the atmosphere is called as transpiration.
2. This happens through the stomata present on the surfaces of the leaves.
3. The desert plants have spine-like leaves to reduce loss of water by transpiration. 
4. Transpiration cools the plant, creates a pull which helps to transport water and minerals & plays a important role in water cycle.

To remember:

1. Photosynthesis take place in the chlorophyll present in leaves.
2. The leaves get the various raw materials required to prepare food.

Presence of starch:

1. During the process of photosynthesis, plants convert carbon dioxide & water into glucose (carbohydrate).
2. Glucose is turned into starch for storage.
3. Starch is a form of carbohydrate.
4. The iodine test confirms the presence of starch in the leaves which in turn confirms the process of photosynthesis.

Iodine Test:

1. Boil a green leaf in water for few minutes till it becomes soft.
2. Then soak this leaf in alcohol till it decolorizes it. This removes the chlorophyll from the leaf.
3. Now dip this leaf in iodine solution.
4. The leaf turns bluish black.
5. This indicates the presence of starch in the leaf.

To remember:

1. Iodine test confirms the presence of starch in leaves.
2. The leaf will turn bluish black is starch is present.
3. Thus confirming that photosynthesis has taken place in the leaf.