ZIMSEC O Level Combined Science Notes: End products of photosynthesis and their fate
- Green leaves manufacture starch or sugar during the photosynthesis process
- Oxygen is also given out.
- The oxygen passes out of the leaves by the process of diffusion.
- It diffuses into the surrounding air.
- There are microscopic holes/pores on the underside surface of leaves.
- These pores are known as stomata (plural) or stoma (singular).
- These pores allow carbon dioxide entry and oxygen to exit the leaf.
- The carbohydrate(starch/sugars) molecules that are formed during the photosynthesis process are transported to other parts of the plant.
- Some parts of the plant have no chlorophyll and thus cannot photosynthesise.
- Carbohydrates are transported as sugars as these molecules are soluble.
- These sugars are transported from the leaves through microscopic tubes to the other parts of the plant.
- This process of transportation is known as translocation.
- The carbohydrates can either be used immediately to supply energy to the plant or they are stored.
- If they are stored they are first converted into starch which is an insoluble compound.
- Starch is stored in the leaves as a source of energy at night or in special organs.
- Some seeds, fruits, roots and tubers for example potatoes contain large amounts of starch.
- Carbohydrates may also be converted into structural molecules in the plant.
- Cellulose is one such strong structural compound formed from carbohydrates.
- It is used to make up cell walls in plants and helps to give plants support.
- Cellulose makes up the fibrous parts of plants.
- The fiber in plants like carrots, sugar cane and mangoes forms an essential part of human diet.
- All this fiber comes is made up of cellulose.
To access more topics go to the Combined Science Notes page.
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