Chapter - 1 Nutrition in Plants

NUTRIENTS:

The components of food necessary for the body are called as nutrients. They enable living organisms to build their bodies, to grow, to repair damaged parts of their bodies and provide the energy to carry out life processes.

NUTRITION:

It is the mode of taking food by an organism and its utilization by the body.

MODE OF NUTRITION IN PLANTS:

AUTOTROPHS:

The mode of nutrition in which the organisms make their own food from simpler substances is called as autotrophic nutrition. For example, Plants prepare their food using water, carbon dioxide and minerals which are available in the surroundings. (Auto- self; trophos- nourishment)

HETEROTROPHS:

The organisms which consume the food prepared by plants are called as heterotrophs. (heteros- other) Some plants which do not possess chlorophyll such as Cuscata also come under this category. It takes food from the host plant on which it is climbing. It is also called as a parasite since it deprives the host plant of its valuable nutrients.

OTHER MODES OF NUTRITIONS:

SAPROTROPHS:

Organisms like fungi take in nutrients from dead and decaying matter. They secrete digestive juices on the dead and decaying matter and convert it into a solution. Then they absorb the nutrients from it.

INSECTIVOROUS PLANTS:

These are insect-eating plants. A part of the leaf is modified into a pitcher like structure. The apex of the leaf forms a lid which can open and close the mouth of the pitcher. Inside the pitcher there are hairs which are directed downwards. When an insect lands in the pitcher, the lid closes and the trapped insect gets entangled into the hair. The insect is digested by the digestive juices secreted in the pitcher.

BASIC TERMINOLOGIES:

CELLS:

The tiny units which make up the body of living organisms are called as cells. They can be seen only under a microscope.

CELL MEMBRANE:

The cell is enclosed by a thin outer membrane which is known as the Cell membrane.

NUCLEUS:

A distinct spherical structure located in the center of the cell is a nucleus. It is surrounded by a jelly-like substance known as cytoplasm.

STOMATA:

The tiny pores present on the surface of the leaves through which the Carbon dioxide in the air is taken in by the leaves for the synthesis of food. These pores are surrounded by guard cells.

CHLOROPHYLL:

It is the green pigment present in the leaves, which helps in capturing the energy of the sunlight. This energy is used to synthesize food.

PHOTOSYNTHESIS:

It is the preparation of food (Carbohydrates, made up of Carbon, Hydrogen and Oxygen) using water, carbon dioxide and chlorophyll in the presence of sunlight. (Photo- light; Synthesis- to combine). Oxygen gets released and carbohydrates get converted into starch during this process. Starch is an indicator of the occurrence of photosynthesis. The solar energy is captured by the leaves and stored in the plant in the form of food. It also takes place in green stems and other green parts. For example, in desert plants photosynthesis is carried by green stems. They also have spine-like leaves to prevent loss of water by transpiration.

PROTEINS:

Proteins are nitrogenous substances containing nitrogen present in the air. Certain bacteria in the soil convert gaseous nitrogen into a usable form and release it in the soil which is utilized by the plants to produce proteins and fats.

SYMBIOTIC RELATIONSHIP:

When organisms live together to share nutrients, they are said to be in a symbiotic relationship. In organisms called lichens, a chlorophyll-containing partner, which is an alga, and a fungus live together. The fungus provides shelter, water and minerals to the alga and, in return, the alga provides food which it prepares by photosynthesis.