The rate of photosynthesis is defined as the amount of oxygen produced per unit mass of green plant tissues or per unit weight of total chlorophyll in a given amount of time. Those factors that have an effect on photosynthesis are those that either increase or decrease the rate of photosynthesis by increasing or decreasing the concentration level of the substances in question.

Photosynthesis is affected by a variety of factors, the most important of which are internal (or plant) and external (or environmental) factors. In order to understand the rate of photosynthesis, it is necessary to first gain an understanding of the factors that influence photosynthesis.

Internal Factors Affecting Photosynthesis:

1. Genetic predisposition and more importantly, plant growth are important factors to consider when considering internal or plant factors.
2. The number, size, age, and orientation of the leaves are some of the factors to consider. It also includes the amount of chlorophyll present, the accumulation of byproducts, and the presence of hormones.

• In terms of chlorophyll content, the chlorophyll in the leaves only serves to act as a biocatalyst. In order to perform photosynthesis, only a small amount of chlorophyll is required to accomplish the task. The rate of photosynthesis is not proportional to the amount of chlorophyll present in the leaves as a result of this phenomenon.
• Accumulation of Byproducts: The accumulation of sugars (the final product of photosynthesis) in the cells of leaves causes the photosynthesis process to be slowed significantly. The process of photosynthesis continues indefinitely as long as the concentration of the products formed (sugars) remains constant in the environment.   

        It is also important to note that the thickness of the cuticle and epidermis of the leaf, as well as the size and distribution of intercellular spaces and the presence or absence of stomata, have an impact on the rate of photosynthesis.

• Protoplasmic Factor: Some internal factors present in the protoplasm of the plant prevent the plants from completing photosynthesis as a result of the presence of these factors. It can be observed in plants that have been transferred from darkness to light and have not yet begun photosynthesis, as well as in other plants.
• Leaf Age: As the age of the leaf increases, the rate of photosynthesis increases until the leaf has fully expanded. However, after this, the rate of photosynthesis decreases due to the effects of aging and senescence, which result in the deactivation of enzymes and the degradation of chlorophyll in plants.

Hormones, in their various forms: Auxins, cytokinins, and gibberellins are among the hormones that stimulate photosynthesis in plants. Because of the closure of stomata, abscisic acid slows down the rate of photosynthesis in plants.

• Protoplasmic Factor: Plants that have been moved from the dark to the light do not immediately begin to produce photosynthesis.

It is due to certain internal factors present in the protoplasm of the plant that prevent it from photosynthesising properly.

CONCLUSION:

By the following article we can know that Some of the internal components are influenced by the genetic content of the plant as well as the rate of growth of the plant. The availability of sunshine, temperature, CO2 concentration, and the availability of water are examples of external influences. The course concludes with a discussion of Blackman’s Law of Limiting Factors, which is discussed in further depth later in the class.