Biology [2 Mark Question Answer]

Chloroplast contains chlorophyll which is used to trap the solar energy from the sunlight which falls on the leaf. This energy is used during photolysis to split the water molecule into hydrogen and oxygen.

(i) A large surface area to absorb water.
(ii) It is positioned at a right angle to the light to get maximum light.
(iii) There are numerous stomata to allow rapid exchange of gases.
(iv) Leaves are thin to allow rapid transport or diffusion of materials.

(1) I will select white light because photosynthesis is maximum in white light while it is minimum in green light as the green light is reflected by green plants.
(2) I will select destarched plant so I Can demonstrate the synthesis of starch through the iodine test.

A destarched plant has no starch present in the leaves and a leaf remains yellowish-brown when tested with iodine during a starch test.
A plant can be destarched by keeping it in the dark for two or three days so that the leaves are free from stored starch.

Blackman (1905) established the law of limiting factors in connection with photo-synthesis. According to this law when a process is conditioned to its rapidity by a number of separate factors, the rate of the process is limited by the pace of the lowest factor, i.e., the factor which is present in a minimum amount.

In respiration, energy is released as a result of oxidation of food, whereas in photosynthesis it is stored up in a carbohydrate molecule. Oxygen is used in respiration whereas it is given out as a by-product in photosynthesis.

During the day transpiration and photosynthesis are interlinked as the stomata opens to facilitate the inward diffusion of carbon dioxide for photosynthesis which also leads to loss of water vapours to the outside during transpiration.

Non-green plants such as fungi and bacteria obtain their nourishment from decaying organic matter in their environment, which comes from dead animals and plants. Thus they are dependent on photosynthesis.

The basic requirements of photosynthesis are:

1. Solar energy from the sun.
2. Green chlorophyll.
3. Carbon dioxide from the air.
4. Water.

Photosynthetic Membrane: A bilayer of lipid molecules in which are embedded proteins that transform light’energy into chemical free energy. (Also known as the thylakoid membrane.)