Question

Internal factors affecting rate of photosynthesis--

1)Protoplasmic factor
2)No.of stomata and their position
3)No.of chloroplast
4)Chlorophyll content


Explain every point.


Give logical answer please....​

Answer 1

1) Protoplasmic Factor

Photosynthesis does not start immediately after the appearance of chlorophyll in very young leaves. It starts after some time. Same thing happens when plants are transferred from dark to light. Thus some internal factor is present in the protoplasm of the cells. This is called “the unknown factor” or the “protoplasmic factor” It is enzymatic in nature.

2) No.of stomata and their position

Many factors of leaf anatomy affect the rate of photosynthesis. These factors influences the diffusion of carbon dioxide thorough the stomata. They also effect on the amount of light reaching the chlorenchyma. These factors are:

(i) Different leaves have different thickness of the cuticle and epidermis.

(ii) They develop palisade. They have different sizes and distributions of the intercellular spaces.

(iii)They have different sizes, positions and distributions of the stomata.

(iv) They develop different types of chlorenchyma and the vascular tissues.

3) No.of chloroplast

Arnon (1954) has demonstrated that cell free chloroplasts are capable of carrying out photosynthesis. This indicates that protoplasm is not necessary for photosynthesis. Thus the chloroplasts are the complete photosynthetic units. They contain all the necessary enzymes.

4)Chlorophyll content

Chlorophyll is essential for photosynthesis. Etiolated plants and non-green tissues do not show photosynthesis. The green cells produce starch in variegated leaves. There are two views about the affect of chlorophyll on photosynthesis:

(i) Willstatter and Stoll: They believe that the rate of photosynthesis is not proportional to the amount of chlorophyll content. The rate of photosynthesis depends on the concentration of enzymes and chlorophyll.

(ii) Emerson (1927): He found a direct relationship between the amount of food formed and the chlorophyll content.