POPULATIONS AND ENVIRONMENT

ATP Synthesis – Photosynthesis & Limiting Factors

ATP Synthesis – Photosynthesis & Limiting Factors

ATP (adenosine triosphate) is the universal currency of energy used by all living organisms. Energy is stored within ATP as chemical energy..

ATP is a nucleotide formed from ADP and a phosphate group (Pi). When ATP is broken down by ATPase enzymes into these two components energy is released.

ATP ? ADP + Pi

However, this process can occur the other way round as well (which requires energy) and ATP molecules are constantly being cycled in both directions.

Photosynthesis

In essence, photosynthesis is the opposite of respiration:

carbon dioxide + water (+ Iight energy) ? glucose + oxygen

Firstly, it’s important to understand the structure of chloroplasts in more detail.

Limiting Factors

The rate at which photosynthesis takes place can be limited by a number of factors:

  • temperature
  • carbon dioxide concentration
  • light intensity

As any of these factors increase, so does the rate of photosynthesis. However, there are limits.

If the temperature becomes too high then the enzymes needed to produce glucose become denatured and so the rate of photosynthesis slows down. A plant has an optimal temperature at which it photosynthesises best.

Light intensity and carbon dioxide could be increased continuously but a plant can only produce so much glucose at one time as it only contains so many thylakoids and enzymes for photosynthesis. This means that a plateau is reached: the optimum rate of photosynthesis.

Plant growers can use this knowledge of limiting factors within commercial greenhouses. They create conditions in which the temperature is kept at the optimum for the plant they’re cultivating. Carbon dioxide is continuously pumped in and the light intensity is kept constant, irrespective of the weather outside.