Nutrition in Plants

Organisms take food to get energy for:

1. Growth and development of the body.
2. Repair of damaged parts of the body.
3. Carrying out life processes like respiration, circulation, etc.
4. Protection against diseases.

Iodine Test:

1. Take a leaf and boil it in alcohol to remove chlorophyll (the green colour).
2. Wash the leaf with water.
3. Add a few drops of dilute iodine solution on the leaf.
4. If the colour changes to blue-black, it indicates the presence of starch.

Green plants make their own food by the process of Photosynthesis.

• Requirements: Carbon dioxide (from air), Water (from soil), Sunlight and Chlorophyll (in leaves).
• Process: Chlorophyll traps solar energy. This energy is used to convert water and carbon dioxide into carbohydrates (food).
• Equation:
  Carbon dioxide + Water --(Sunlight/Chlorophyll)--> Carbohydrate + Oxygen

Flowchart:

Sun (Energy Source) -> Plants (Producers) -> Herbivores (e.g., Deer/Cow) -> Carnivores (e.g., Lion/Tiger)

All heterotrophs directly or indirectly depend on plants for food.

(a) Green plants are called autotrophs since they synthesise their own food.

(b) The food synthesised by plants is stored as starch.

(c) In photosynthesis solar energy is absorbed by the pigment called chlorophyll.

(d) During photosynthesis plants take in carbon dioxide and release oxygen gas.

(i) A parasitic plant with yellow, slender and branched stem: Cuscuta (Amarbel).

(ii) A plant that is partially autotrophic: Pitcher plant (Insectivorous).

(iii) The pores through which leaves exchange gases: Stomata.

(a) Cuscuta is an example of:
(i) Autotroph (ii) Parasite (iii) Saprotroph (iv) Host

(b) The plant which traps and feeds on insects is:
(i) Cuscuta (ii) China rose (iii) Pitcher plant (iv) Rose

Plants that eat insects to fulfill their nitrogen requirement are called Insectivorous Plants. Example: Pitcher plant, Venus flytrap.

Some organisms live together and share both shelter and nutrients. This relationship is called Symbiosis.
Example: Lichens (Algae and Fungus live together). Algae provides food and Fungus provides shelter and water.

Definition: The process by which green plants make their own food using sunlight, carbon dioxide, and water.

• Chlorophyll: Green pigment in leaves that captures solar energy.
• Stomata: Tiny pores on leaf surface for gas exchange (intake of CO2).
• Vessels: Pipe-like structures to transport water and minerals from roots to leaves.

Equation: Carbon dioxide + Water -> Carbohydrate (Starch) + Oxygen

• Parasitic: Non-green plants live on other plants (Host) and suck their readymade food. (e.g. Cuscuta/Amarbel).
• Insectivorous: Plants that eat insects to get nitrogen. They usually grow in nitrogen-deficient soil. (e.g. Pitcher Plant).
• Saprotrophic: Organisms take nutrients from dead and decaying matter. (e.g. Fungi like Mushroom, Bread mould).
• Symbiotic: Two organisms live together and share shelter and nutrients. (e.g. Lichens = Algae + Fungus).

Plants absorb nutrients like Nitrogen, Phosphorus, and Potassium from the soil. To prevent soil from becoming infertile:

• Farmers add **Manure** and **Fertilizers**.
• Leguminous plants (pulses, gram, peas) have **Rhizobium** bacteria in their roots. Rhizobium converts atmospheric nitrogen into soluble form for the plant.

• Autotrophs: Organisms that make their own food (e.g. Green Plants).
• Heterotrophs: Organisms dependent on others for food (e.g. Animals, Humans).
• Photosynthesis: Process of food manufacture in plants.
• Host: The plant on which a parasite climbs.
• Parasite: The organism that derives food from the host.

• Leaves are the "Food Factories" of plants.
• Sun is the ultimate source of energy for all living organisms.
• Mushroom is a saprotroph (Fungi).
• Rhizobium cannot make its own food. It lives in root nodules.