Photosynthesis

Equation for photosynthesis

Carbondioxide + water = glucose +oxygen

6 CO2 + 6 H2O → C6H12O6 + 6 O2

What type of reaction is photosynthesis?

Photosynthesis is an endothermic reaction in which energy is transferred from the environment to the chloroplasts by light.

Limmiting factors of photosynthesis

Light intensity

carbondioxide

chloroplast/chlorophyll

temperature

Why is water not considered as a limmiting factor for photosynthesis?

If water availability is low, plants close their stomata to stop transpiration, meaning that photosynthesis is limited by carbon dioxide

How does the temperature effect the rate of photosynthesis

• As temperature increases the kinetic energy increases so there are more successful collisions between reactants and enzymes which results in the formation of more products.

• However, at higher temperatures, enzymes that control the process of photosynthesis get denatured which starts reducing the rate at a rapid speed.

How does light effect the rate of photosynthesis

* The higher the light intensity the faster the rate of photosynthesis
* as the intensity of the light available to the plant will depend on the amount of energy that it has to carry out photosynthesis.
* This trend continues until some other factor required for photosynthesis becomes limitting

How does carbondioxide concentration effect the rate of photosynthesis

* Carbon dioxide is one of the raw materials required for photosynthesis
* this means the more carbon dioxide that is present, the faster the reaction can occur.
* The tred continues until some other factor required for photosynthesis becomes limitting

How does chlorophyll effect the rate of photosynthesis? How is the amount of chlorophyll effected?

The more chloroplasts (as they contain chlorophyll which absorbs light energy for photosynthesis) a plant has, the faster the rate of photosynthesis.

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The amount of chlorophyll can be affected by

* disease
* lack of nutrients such as magnesium
* loss of leaves (fewer leaves means fewer chlorophyll)

What is the relationship between light intensity and distance?

as the distance increases the light intensity decreases. They are inversly proportional to each other.

What is the glucose produced in photosynthesis used for?

* Respiration
* converted into insoluble starch for storage
* to produce fat or oil as storage (often in seeds)
* to produce cellulose, which strengthens the cell wall
* to produce amino acids for protein synthesis

Write a method for explaining the rate of photosynthesis

1. Set up a test tube rack containing a boiling tube at a distance of 10 cm away from the light source.
2. Fill the boiling tube with the sodium hydrogen carbonate solution.
3. Put the piece of pondweed into the boiling tube with the cut end at the top. Gently push the pondweed down with the glass rod.
4. Leave the boiling tube for 5 minutes.
5. Start the stopwatch and count the number of bubbles produced in one minute.
6. Repeat the count twice more. Then use the data to calculate the mean number of bubbles per minute.


7. Repeat steps 1‒7 with the test tube rack and boiling tube at distances of 20 cm, 30 cm and
40 cm from the light source.

What improvements can you make in the photosynthesis experiment to make it more reliable

* Use a gas syringe to collect the volume of gas produced
* Repeat the experiment at least twice for each distance and calculate the mean number of bubbles
* Use of a glass tank between lamp and plant to prevent heating of the plant, or using an LED bulb that releases very little heat energy