What is nutrition ?
Nutrition is the process through which an organism consumes food and uses it in some way. While humans and other animals are either directly or indirectly reliant on plants for their nourishment, green plants prepare their own food.
Modes of Nutrition
On the basis of a different mode of nutrition, organisms are categorized into two major types,
1) Autotrophs, or self-nourishing organisms By using the process of photosynthesis, organisms that practise autotrophic feeding produce their own food from basic elements like CO2 and H2O. Plants are hence referred to as autotrophs.
2) Heterotrophic (other) Because they lack chlorophyll, humans and other animals must rely on plants to produce their food. The term "heterotroph" refers to a creature that consumes nourishment from living things such as plants or animals because it cannot produce it on its own.
Photosynthesis: Food Making Process in Plants
Photosynthesis is the process by which autotrophic green plants produce their own food from uncomplicated inorganic elements (carbon dioxide and water) in the presence of sunlight and the green pigment chlorophyll.
Site of Photosynthesis
Green leaves are known as the food factories of plants because they are where photosynthesis takes place. The. Other green sections of the plant-like stem may also engage in photosynthetic activity, but this is insufficient to supply all of the needs of the plant.
Reactions Involved in Photosynthesis
The whole process of photosynthesis can be given by the following equation:
Cells
All biological things are constructed from discrete catted cell building blocks. All living things have structural and functional elements called cells that make up their bodies. They are only visible using a microscope. The cell is composed of a jelly-like liquid called cytoplasm that surrounds the nucleus, a distinct, centrally situated spherical structure called the nucleus, and a thin outer layer of material called the cell membrane.
Plants absorb CO2 through stomata and water through roots, using vessels as nutrient transportation pipes from roots to leaves.
Sunlight is captured by chlorophyll in plant leaves, enabling photosynthesis to produce food (starch) and release oxygen, making the sun the ultimate energy source for all living organisms.
Products of Photosynthesis
Photosynthesis primarily produces carbohydrates, with glucose as the main food material that is converted into starch, indicating the occurrence of photosynthesis when present in leaves.
Importance of Photosynthesis
No photosynthesis means no food and oxygen production, making life on Earth impossible without this vital process.
Photosynthesis in Leaves of Various Colours
Leaves of plants with red, brown, or violet colors also perform photosynthesis and synthesize starch, despite the presence of large amounts of non-green pigments that mask the green chlorophyll color.
Synthesis of Plant Food other than Carbohydrates
Plants synthesize starch or glucose, the simplest carbohydrates containing carbon, hydrogen, and oxygen. These can be converted into fats, proteins, etc. Seeds like wheat, rice, and potato tubers are rich in starch or glucose, while oilseeds like sunflower store them as oil. When plant nutrients contain carbon, hydrogen, oxygen, and nitrogen elements, they are called proteins. Nitrogen is obtained from soil as nitrate by soil bacteria, forming amino acids that are converted into proteins. So, plants also produce fats and proteins as their food.
Insectivorous Plants
Insectivorous plants, also known as carnivorous plants, trap insects to obtain nitrogen compounds (amino acids) since they lack nitrogen elements in the soil. They have specialized leaves with lids that close the mouth of the pitcher, where digestive juices break down trapped insects for nutrition. Examples include pitcher plants, sundew, Venus flytrap, and bladderwort. These plants are considered partial heterotrophs as they can produce their own food but rely on insects to fulfill their nitrogen needs.
Saprotrophic Plants
Saprotrophic nutrition is when organisms, like fungi, obtain nutrients from dead and decaying matter.
Symbiotic Plants
Symbiotic plants form a mutual relationship, where two different species live together, sharing food and shelter. Lichens, for example, are a symbiotic association between algae and fungi. The fungus provides shelter and nutrients to the algae, while the algae produce food through photosynthesis.
Replenishment of Nutrients in Soil
Rhizobium bacteria in the root nodules of leguminous plants convert atmospheric nitrogen into soluble compounds, providing the plants with readily available nitrogen for protein synthesis. In return, leguminous plants offer food and shelter to the bacteria in a symbiotic relationship. This association is beneficial to farmers as it eliminates the need for nitrogen fertilizers when growing leguminous crops.
