What are Plants?
Plant cell have plastids, which is not present in animal cell.
Plants have cell wall, which is absent in animal cell.
• Nutrients are compounds in foods which are essential to life and health, providing us with
energy, the building blocks for repair and growth and substances necessary to
regulate chemical processes.
Chemical processes are the processes that takes place inside the body of a living organisms, the chemical process requires energy and that energy is provided by the food we eat.
• A nutrient is a substance which are used by an organism to survive, grow, and perform many
The process of obtaining food and its utilization in the body in such a way that it provides energy is called nutrition.
Autotrophs and Heterotrophs
• Organisms that make food by themselves with the help of chloroplast are called autotrophs.
• Plants are an example of autotrophs as they make their own food using carbon
dioxide, water and light energy, with the help of chloroplast already a part of the leaf.
• Organisms that depend on others and usually take in ready-made food made by the
autotrophs and thus are called heterotrophs.
• Animals are an example of heterotrophs as they depend on plants in many ways for their food.
- Process of making food by green plants occur in the presence of sunlight and thus called PHOTOSYNTHESIS.
- Photo means Light and synthesis means to combine.
- Photosynthesis means in the presence of light and chlorophyll it combines to form food.
- Plants absorbs water & minerals from soil by roots.
- Plants get water from the rain, nearby river and many made process.
- Plants get minerals from the soil nd the weathered rocks.
- The absorbed water is pulled or pushed up to the leaves through stem.
- Green leaves absorb carbon dioxide from the air through pore present on their undersurface.
- These pores are called STOMATA.
- The stomata are opened and closed through guard cells.
- Guard cells play a very important role as it helps in the entry of Carbon dioxide and removal of oxygen.
MECHANISM OF PHOTOSYNTHESIS
- There are large number of stomata present on the under surface of leaves.
- Each stomata include two bean shaped structure called guard cells enclosing a pore called STOMATAL PORE.
- The stomata can be bean shaped in dicots and monocots have dumbbell shaped stomata.
- Guard cells regulate the opening and closing of the stomatal pore and thus are the most essential part of the leaf.
- Gas exchange can also occur from lenticels, the lenticels are present on the stem of woody plants.
- The inner walls of guard cells are thick, whereas the outer wall are thin.
- When water moves into the guard cells, they become turgid ( full of water) & curve away from each other leaving the stomatal pores open and results in entry of CO2
- After loosing water, the guard cells becomes flaccid and both come together in such a way that the stomatal pores closes.
HETEROTROPHIC NUTRITION IN PLANTS
- The plants which derive nutrition from the host plant is called parasitic plant.
- Host plants are those plant on which the other plant is dependent for their nutrition.
- The parasitic plant are those plants which depends either totally or partially on the host plant to derive their nutrition.
- The parasitic plants which are totally dependent on the hos plant lacks chlorophyll.
- The parasitic plants which are partially dependent on the host plant have chlorophyll but lack necessary elements to complete photosynthesis.
- Total stem parasite: Cuscuta
- Total root parasite: Rafflesia
- Partial root parasite: Santalum
- Partial stem parasite: Viscum
- Sapro means rotten.
- The plants which depends on dead and decaying organisms are called Saprotrophic plants.
- Example: Monotropa.
- It is a type of association in which the two organisms are living in such a way that both are benefiting each other.
- Lichens comprises of algae and fungus, where the algae have chlorophyll thus it can prepare its own food and it provides nutrition to the fungus and on the other hand the fungus provides shelter to the algae, thus both are beneficial to each other.
- Rhizobium bacteria and the leguminous plants.
- These are the bacteria found in the root nodules of leguminous plants. (Pulses)
- Those plant which fixes atmospheric nitrogen to the soil is called leguminous plant.
- Ex: Pea plant, Alfalfa, beans etc.
- Rhizobium fixes atmospheric nitrogen and converts it into ammonia.
- It also enriches soil with nitrogenous minerals.
- These plants are also known as Insectivorous plants.
- •They are green plants, thus they have chlorophyll, so they are able to make their own food but they grow in soil which lack mineral nutrients, thus do not have basic requirement to complete the process of photosynthesis.
- These plants trap insects, kill them, digest and absorb nitrogenous nutrition from their body.
- Eg: Nepenthes, Drosera