What is photosynthesis?
Plants make their own food using photosynthesisA chemical process used by plants to make glucose and oxygen from carbon dioxide and water, using light energy. Oxygen is produced as a by-product of photosynthesis. Algae subsumed within plants and some bacteria are also photosynthetic.. The food produced is the sugar called glucose. Food produced by plants is important, not only for the plants themselves, but for other organisms that feed on the plants.
algaeA group of organisms that photosynthesise but lack the complex range of cell types and organs found in land plants. Most algae are aquatic. All have chloroplasts. can also make their own food by the process of photosynthesis. Plant biomassThe dry mass of an organism. will increase as a result of photosynthesis.
During photosynthesis, plants produce glucoseA simple sugar used by cells for respiration. and oxygen from carbon dioxideA gaseous compound of carbon and oxygen, which is a by-product of respiration, and which is needed by plants for photosynthesis. and water, using light energy from the Sun.
The following equations summarise what happens in photosynthesis:
\(\text{carbon dioxide} + \text{water} \xrightarrow[chlorophyll]{light} \text{glucose}+ \text{oxygen}\)
Photosynthesis is an endothermicReaction in which energy is taken in. reaction as it requires light energy to react carbon dioxide and water to produce glucose and oxygen.
The light energy required is absorbed by a green pigment called chlorophyllThe green chemical inside the chloroplasts of plant cells. It enables photosynthesis to take place. in the leaves. Chlorophyll is located in chloroplastContains the green pigment chlorophyll; the site of photosynthesis. in plant cellBasic unit of life. Unicellular organisms only have one cell. Multicellular organisms have many cells..
Plant leaves are the main organA group of different tissues that work together to carry out a particular function, eg heart and lungs. for photosynthesis.
The carbon dioxide required for photosynthesis comes from the air. It enters leaves through the stomataTiny holes in the epidermis (skin) of a leaf. They control gas exchange by opening and closing and are involved in loss of water from leaves. Singular is stoma.. Water enters the plant through the roots, and is transported to the leaves in the xylem vesselsNarrow, hollow, dead tubes with lignin, responsible for the transport of water and minerals in plants..
Oxygen is formed as a product. Some is used for respiration. During the day, provided the rate of photosynthesis is high enough, plant and algae give out oxygen.
Some of the glucose produced by photosynthesis is used for respirationThe chemical change that takes place inside living cells, which uses glucose and oxygen to release the energy that organisms need to live. Carbon dioxide is a by-product of respiration..
Glucose is the starting point for making the materials that plants need to live. These materials are used to make cell walls and other cell components and will enable the plant to growth and increase in biomass.
The glucose not used for respiration is used in the following ways: