Aim- My aim is to test if the rate of photosynthesis increases or decreases when a piece of Canadian Pond Weed is put in a tray of water with a lamp at different distances.
Introduction- Photosynthesis is a procedure that takes place in the leaf. The formula is:
Photosynthesis takes place when the chlorophyll (that is in the chloroplast) converts the carbon dioxide and water (with a little help from light and chlorophyll itself). Which is turned into glucose (which is then turned into starch which is used for energy) and oxygen (which is passed out through the leaf as a waste product). There are a few things that could limit the rate of photosynthesis, these are the amount of carbon dioxide, the amount of minerals, the temperature, the amount of water and the amount of water (this is what our experiment is based on). The cells that carry out photosynthesis are called palisade cells. These are rectangular and full of chloroplasts. Lots of palisade cells make up the palisade tissue. All the cells make up a tissue that makes food for the plant. Energy is needed in photosynthesis. The energy comes from sunlight. Chlorophyll is a substance that absorbs sunlight. The light energy is used to convert carbon dioxide and water into sugars. The sugars are the plant food. Oxygen is made as a waste product. During photosynthesis the energy from the sunlight becomes converted into the chemical bond energy in the sugars. Most photosynthesis takes place in the leaves. So most of the food is carried around the plant in its transport system. Then there is a way that it goes around, first it is used in respiration to give the plant energy. Some of the sugar is changed to starch and stored in the roots for future use. Some of the sugar is used to make cellulose; this is needed for the plant cell walls. Sugars can be made into other substances like amino acids; the sugars and nitrogen make this. Other substances are fats and oils; these are used for storage in seeds. Oxygen is also a product of photosynthesis. This replaces the oxygen that is used in respiration. Many plants spread their leaves to catch as much light as they can. Light that is too strong can damage the chloroplasts. Things like light intensity can affect the rate of photosynthesis – this is called the limiting factor. It doesn’t matter if the plant has lots of carbon dioxide and water and a nice warm temperature. If light is in a short supply, then light will limit the rate of photosynthesis. The only way to increase the rate of photosynthesis is to increase the limiting factor. Only one factor can limit the rate of photosynthesis at any one given time. It normally depends on which one is in the shortest supply. An increase in temperature usually increases the rate of photosynthesis. Most chemical reactions increase with temperature. But at about 40˚C the rate slows down. At temperatures above this, the rate drops quickly. This is because the enzymes in photosynthesis are being destroyed. The plant can use the glucose it makes during photosynthesis in several ways; one is that it is used in respiration. Another is that glucose can be changed into starch, which is stored for later use and glucose can be built up into other large molecules such as cellulose or protein. These substances are used for growth and repair of the plant.
