FUNCTION OF LEAVES

STORAGE OF FOOD:

Some plants store excess food within the leaves. E.g. Cabbage

SYNTHESIS OF FOOD:

· Leaves are considered as the kitchen of a plant because within the leaves, plants make their food. This process is called photosynthesis.

PHOTSYNTHESIS:

· During day time the stomata remain open. Through the stomata the leaves get air containing carbon-dioxide from the atmosphere.

· Water, mixed with minerals reaches the leaves from the soil through the different parts i.e. roots, stem, branches and twigs.

· Leaf cells have green pigment called chlorophyll.

· The sunlight reaches the leaves through their skin and is absorbed by the chlorophyll.

· Using the energy of sunlight absorbed by the chlorophyll leaves change water and carbon dioxide into sugar (glucose i.e. carbohydrates) and oxygen is given out.

· Some of the sugar is used by the plant as food to grow. Some of the sugar is changed into starch.

· The rest of the sugar and the starch are stored in different parts of the plant.

The process of photosynthesis may be represented as-

RESPIRATION:

Respiration is a process which majorly occurs during the night, when no photosynthesis occurs. Plant respiration occurs 24 hours per day, but night respiration is more evident since the photosynthesis process ceases.

· During respiration, oxygen is taken in and carbon di oxide is given out.

· Here the leaves act as the breathing organ.

· The stomata of leaves help plants to intake oxygen and give out carbon dioxide.

· It is the reverse process of photosynthesis.

REMOVAL OF EXCESS WATER:

· Roots absorb more water than it is required by a plant.

· Excess water is thrown out through stomata of leaves.

· The process to get rid of excess water by a plant in the form of water vapour is called transpiration. So, transpiration occurs through the stomata.

PLANT RESPIRATION AND PHOTOSYNTHESIS

Respiration:

oxygen + glucose -> carbon dioxide + water +
heat energy

Photosynthesis:
carbon dioxide + water+ light energy -> oxygen + glucose

It Depends on the amount of sunlight, plants can give out or take in oxygen and carbon dioxide:

DARK:

· Only respiration takes place.

· Oxygen is consumed while carbon dioxide is released.

DIM SUNLIGHT

· Photosynthesis rate is same as respiration rate.

· A plant consumes all the oxygen photosynthesis generates.

· It also uses all the carbon dioxide respiration creates.

· As a result, no gas exchange takes place with the environment.

BRIGHT SUNLIGHT

· Photosynthesis uses carbon dioxide and makes oxygen faster than respiration produces carbon dioxide and consumes oxygen.

· Extra oxygen is released into the atmosphere.

Reproduction:

Young plants may grow from leaves of some plants. In case of bryophyllum,

baby plants grow from the edge of its leaves if these are placed in moist soil.