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.
· 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 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
oxygen + glucose -> carbon dioxide + water +
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:
· Only respiration takes place.
· Oxygen is consumed while carbon dioxide is released.
· 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.
· Photosynthesis uses carbon dioxide and makes oxygen faster than respiration produces carbon dioxide and consumes oxygen.
· Extra oxygen is released into the atmosphere.
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.