Photosynthesis
Plants, unlike animals, can make their own food. They do this using a process called A 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..
During photosynthesis, plants produce A simple sugar used by cells for respiration. from simple A compound that does not include carbon combined with hydrogen. molecules - A 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.
Photosynthesis requires energy to drive the chemical reaction. Photosynthesis is an Reaction in which energy is taken in. reaction. This means it cannot occur without energy (from the Sun).
The light required is absorbed by a green A coloured chemical. called The green chemical inside the chloroplasts of plant cells. It enables photosynthesis to take place. in the leaves. Chlorophyll is found in Contains the green pigment chlorophyll; the site of photosynthesis. in plant Basic unit of life. Unicellular organisms only have one cell. Multicellular organisms have many cells., particularly the Plant tissue containing closely packed cells in the upper layer of a leaf. and spongy The plant tissue in a leaf which has loosely packed cells and air spaces between them to allow gas exchange..
Plant leaves are the main photosynthetic A group of different tissues that work together to carry out a particular function, eg heart and lungs., but other parts of the plant exposed to the light can develop chlorophyll and photosynthesise.
The carbon dioxide required for photosynthesis comes from the air. It enters leaves through the Tiny 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 Narrow, hollow, dead tubes with lignin, responsible for the transport of water and minerals in plants..
Oxygen is formed as the waste product. Some is used for respiration by the plant. The excess is released from the leaves, making it available for respiration to animals and many microorganisms. During the light, provided the rate of photosynthesis is sufficiently high, plants, give out oxygen.
Photosynthesis in detail
The overall reaction for photosynthesis as given above is a simplification. Photosynthesis involves several different chemical reactions, but these can be summarised in two main stages. In the first reaction, energy is used to split water molecules into hydrogen and oxygen. The hydrogen is needed for the second stage of reactions and the oxygen is released by the plant as a waste product. In the reactions of the second stage, the hydrogen is combined with carbon dioxide to make glucose.
Biosynthesis
Some of the glucose produced by photosynthesis is used for The 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 the The production of more complex molecules, from simpler ones, in living organisms. of materials that plants need to live.
The glucose not used for respiration is used in the following ways:
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