The equation for photosynthesis
carbon dioxide + water (+ light energy) → glucose + oxygen
Factors limiting photosynthesis
Three factors can limit the speed of photosynthesis - light intensity, carbon dioxide concentration and temperature.
If it gets too cold, the rate of photosynthesis will decrease. Plants cannot photosynthesise if it gets too hot.
Carbon dioxide concentration
Sometimes photosynthesis is limited by the concentration of carbon dioxide in the air. Even if there is plenty of light, a plant cannot photosynthesise if there is insufficient carbon dioxide.
Without enough light, a plant cannot photosynthesise very quickly, even if there is plenty of water and carbon dioxide. Increasing the light intensity will boost the speed of photosynthesis.
Farmers can use their knowledge of these limiting factors to increase crop growth in greenhouses. They may use artificial light so that photosynthesis can continue beyond daylight hours, or in a higher-than-normal light intensity. The use of paraffin lamps inside a greenhouse increases the rate of photosynthesis because the burning paraffin produces carbon dioxide, and heat too
What is photosynthesis?
Photosynthesis is the chemical change which happens in the leaves of green plants.
During this reaction, carbon dioxide and water are converted into glucose and oxygen. The reaction requires light energy, which is absorbed by a green substance called chlorophyll.
These contain chloroplasts, which are tiny objects containing chlorophyll.
Plants and minerals
Plants need to take in a number of elements to stay alive. The most important are:
Plants get hydrogen and oxygen from water in the soil, and carbon and oxygen from carbon dioxide and oxygen in the atmosphere. Water and carbon dioxide are used to synthesise food during photosynthesis. Oxygen is used to release energy from food during respiration.