photosynthesis

photosynthesis

1. what is photosynthesis?

   • photosynthesis carries out three very important functions for the continued existence of life on earth:
     • photosynthesis results in plants giving off oxygen which is essential for many living organisms
     • photosynthesis removes carbon dioxide from the air and prevents it from reaching a poisonous level
     • photosynthesis provides food for most living organisms on the earth
   • photosynthesis is the way plants make their own food using light
     • photo - light
     • synthesis - produce/make
   • equations:
     • word: carbon dioxide + water -------> glucose + oxygen
     • chemical: 6CO2 + 6H2O ---------> C6H12O2 +6O2

2. how do plants photosynthesise

   • for photosynthesis to take place:
     • 1. plants take the carbon dioxide from the air through tiny pores on their leaves called stomata
     • 2. plants take in water from soil through their roots
     • 3. sunlight is absorbed by the chloroplasts in the cells of the leaves of the plant
     • 4. the green pigment chlorophyll in the chloroplasts allows the carbon dioxide and water to combine to form glucose
     • 5. the energy for this reaction comes from sunlight
     • 6. oxygen is released and given off as a waste product

3. photosynthesis as a chemical process

   • that may be described as a process because it involves a number of steps
   • it is a chemical process because it happens in living cells

4. photosynthesis as a biological process

   • photosynthesis occurs in the chloroplasts of living cells
   • it is a biological process because it happens in living cells

5. factors that affect photosynthesis

   • carbon dioxide
   • temperature
   • light