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B4 A) Photosynthesis
B4 A) Photosynthesis
Plants create glucose through a reaction called photosynthesis. Photosynthesis is where plants turn carbon dioxide and water into glucose and oxygen. The equation for photosynthesis is the respiration reaction in the opposite direction. The word and chemical equation for photosynthesis are shown below.
You do not need to remember the chemical equation.
Light energy is needed in order for photosynthesis to take place – photosynthesis does not happen at night because there is no light. As light energy is required for photosynthesis to take place, it means that photosynthesis is an endothermic reaction (a reaction that takes in energy from its surroundings; there is more energy in the products than the reactants).
Photosynthesis takes place in the chloroplasts in green plant cells. The chloroplasts contain a green pigment called chlorophyll, and chlorophyll is responsible for absorbing light energy. The leaves of plants are where the majority of the photosynthesis takes place, and the cells in the leaves contain lots of chloroplasts.
Light energy is needed in order for photosynthesis to take place – photosynthesis does not happen at night because there is no light. As light energy is required for photosynthesis to take place, it means that photosynthesis is an endothermic reaction (a reaction that takes in energy from its surroundings; there is more energy in the products than the reactants).
Photosynthesis takes place in the chloroplasts in green plant cells. The chloroplasts contain a green pigment called chlorophyll, and chlorophyll is responsible for absorbing light energy. The leaves of plants are where the majority of the photosynthesis takes place, and the cells in the leaves contain lots of chloroplasts.
Uses of the Glucose that is Made
The whole point of photosynthesis for plants is to make glucose. Plants use glucose in a few different ways.
One use of the glucose produced by photosynthesis is so that the plant can respire; it is important to remember that plants can photosynthesise and respire. When glucose is broken down, it releases energy for a variety of different activities (respiration is an exothermic reaction; energy is given out). An example of where plants undertake respiration is in the root hair cells. The root hair cells use active transport to bring in as many nitrates/ minerals as possible to ensure that the plant has everything that it needs to grow healthily. Energy is needed for active transport and the energy comes from respiration reactions (active transport is where substances go against a concentration gradient [from a low concentration to a high concentration]. Energy is required in order for active transport to take place. Click here for more information on active transport in root hair cells).
Plants also use the glucose to create materials that they need to live. This process is known as biosynthesis, which is where a living organism creates more complex molecules from simpler ones. Some of the materials that plants makes are:
The whole point of photosynthesis for plants is to make glucose. Plants use glucose in a few different ways.
One use of the glucose produced by photosynthesis is so that the plant can respire; it is important to remember that plants can photosynthesise and respire. When glucose is broken down, it releases energy for a variety of different activities (respiration is an exothermic reaction; energy is given out). An example of where plants undertake respiration is in the root hair cells. The root hair cells use active transport to bring in as many nitrates/ minerals as possible to ensure that the plant has everything that it needs to grow healthily. Energy is needed for active transport and the energy comes from respiration reactions (active transport is where substances go against a concentration gradient [from a low concentration to a high concentration]. Energy is required in order for active transport to take place. Click here for more information on active transport in root hair cells).
Plants also use the glucose to create materials that they need to live. This process is known as biosynthesis, which is where a living organism creates more complex molecules from simpler ones. Some of the materials that plants makes are:
- Most of the glucose is converted into starch and the starch is stored in the leaves, roots and stems. The starch can then be used when photosynthesis isn’t happing, such as in the winter. Starch is insoluble in water (does not dissolve in water). This makes starch a better way to store glucose than glucose. This is because glucose is soluble in water (can dissolve in water), which means that cells that contain a lot of glucose will take in water due to osmosis and swell up (osmosis is where water molecules move through a partially permeable membrane from a region of higher water concentration to a region of lower water concentration).
- Some of the glucose is converted into cellulous, which is used to make the cell walls of plant cells strong.
- Some of the glucose is converted into fats and oils that are stored in seeds.
- Some of the glucose is combined with nitrates that the plant has absorbed from the soil to make amino acids. The amino acids are then used to create proteins.