Photosynthesis
This section examines the physiology of photosynthesis and how it related to agriculture and food production. The value of photosynthesis as an oxygen producing process is examined and is related to the maintenance of the composition of the atmosphere.
Photosynthesis is a chemical reaction in plants to make food. It only occurs in the presence of light.
Word Equation
- Carbon Dioxide + Water
glucose + oxygen
Symbol Equation
- CO2 + H20 --> C6H12O6 + O2
- Light Energy
- CO2
- H20
Limititng Factors - you need all three for photosynthesis to occur
- Light - Light increases, rate of photosynthesis increases up to a certain point
- CO2 - CO2 increases, rate of photosynthesis increases up to a certain point
- Temperature - must not get too hot or too cold
- Light - artificial light, during night, especially red or blue, grow in unshaded areas
- CO2 - Have a canister of CO2 in greenhouse
- Temperature - find a warmer place. Use a greenhouse
- CO2 enters through the stomata
- Spongy cells have a space for exchange of gasses
- Chloroplasts in paliside celss, on the upper surface of leaf, most light on that part
- Xylem - Carries water from roots to leaf. Phloem carries glucose from leaves to rest of the plant.
- Put leaf in boiling water for 15 seconds. This kills it, makes it soft, makes cell walls permeable
- Put leaf in alcohol in test tube. Put the test tube in hot water bath. This decolourises it.
- Remove and wash the leaf
- Put iodine of the leaf
- If starch is present, the leaf turns blue black.
Nitrogen - Nitrogen as nitrates is absorbed from the soil to make protein.
You will also need to know tests for whether a plant needs light, does it need CO2 , and is O2 produced.
The first two can be done with putting them without the variable, and then testing for starch.
Oxygen test will come here later. Check it on google you will find it.