Photosynthesis and Its Requirements

Photosynthesis: Green plants which are autotrophic, synthesize food through the process of ‘photosynthesis’. It is the process by which green plants having chlorophyll, synthesize the simple sugar (glucose) from simple raw materials water and carbon dioxide using the energy from the sunlight. Oxygen is released in this process. The overall equation of photosynthesis is given.The sugar produced is stored in the form of starch in plants (in animals food is stored in the form of glycogen). Since autotrophic plants are able to produce food, they are also known as ‘producers’.

Site of Photosynthesis: All green plants are capable of performing photosynthesis; the leaves are the most suitable organs for this process. The cells of the leaves contain special organelles called ‘chloroplasts’ which are the main sites of photosynthesis. These are plastids which contain light absorbing green pigment chlorophyll.

Requirements of Photosynthesis: It requires chlorophyll, carbon dioxide, water and sunlight.

Chlorophyll: it is a green pigment, found in all photosynthetic organisms and is responsible for their green color. In plants, it is mainly found in leaves.

Carbon dioxide: air contains 0.03% carbon dioxide. Terrestrial plants use atmospheric carbon dioxide in photosynthesis. Aquatic plants use the carbon dioxide dissolved in water. Plants obtain carbon dioxide through pores called ‘stomata’ present on the surface of leaves. The opening and closing of these pores are regulated by guard cells.

Water: is an important raw material for photosynthesis. Plants absorb water from the soil through their root hairs and then transported up to the leaves through stem.

Sunlight: light energy is used in splitting water molecules into hydrogen and oxygen. The splitting of water in the presence of light is called ‘photolysis’.

Other material: nitrogen, phosphorus, iron and magnesium are also required for photosynthesis and are taken up from the soil. Nitrogen is an essential element used in synthesis of proteins. It is taken up in the form of inorganic nitrates.

Sample Questions

(More Questions for each concept available in Login)

Question : 1

Chlorophyll is present in an animal cell.
A. True	B. False	C. Some times	D. Yes, in the chloroplast
Right Option : B
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Question : 2

Grana refers to ______________________
A. Stacks of thylakoids		B. Stacks of quantasomes
C. By-product of photosynthesis		D. Glycolysis of glucose
Right Option : A
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