During photosynthesis, when the plant takes in carbon dioxide and water, oxygen is released into the air and also the plant produces glucose.
The glucose made by the plant is stored as starch in the roots of the plant when it is not needed. The starch is changed back to glucose when the plant requires it. The glucose is needed for respiration for the plant and provides energy for growth.
When the plant releases the oxygen, humans and animals therefore use oxygen for respiration.
What things have I chosen to investigate?
I have chosen to investigate the effect of the amount of light intensity on the rate of photosynthesis.
I think the rate of photosynthesis will increase when the amount of light intensity increases and decrease when the light intensity is decreased.
I think this will happen because the light is essential for photosynthesis, so the more light there is the more photosynthesis will take place.
This is because the light that has been absorbed by the chloroplasts in the leaf of the plant splits the water into oxygen and hydrogen. The oxygen is then released in to the air so that humans and the animals can respire. The hydrogen joins with the carbon dioxide to form into glucose. The glucose is then stored as starch in the roots of the plant.
Light Reaction
H2 O (Absorbed by the roots). + CO2 (Taken in from the air by the roots).
H2
O2
C6H12O6
O2 (gets released into the air).
By increasing the amount of carbon dioxide, water, and the amount of leaves on a plant, this could make photosynthesis occur faster.
How will I do the experiment?
To collect my results I must use the following equipment:
- Beaker – to hold the water and the plant inside it
- Test tube – to collect the oxygen which is to be released
- Lamp – providing the light for the plant to photosynthesise
- Ruler – measure the distance between the beaker and the lamp
- Funnel – placed over the plant so that the oxygen that is produced does not get lost in the water
- Stop clock – to record the time during the experiment
Test tube
Lamp
Beaker
Funnel
Water plant Ruler
Measurements
I know that the rate of photosynthesis has changed because I will be monitoring the number of bubbles being released by the plant each minute.
In my results table I will be writing the number of oxygen bubbles released by the plant.
I will write down my results every minute.
Results Table
Evaluating Evidence
I think the investigation was not done in the best way because a bubble could have been missed and affect the results. The volume of the bubbles could have been confused, as there are bubbles of different volumes and will give inaccurate results and that will give false information about photosynthesis.
I think the experiment gave fairly accurate results. The temperature of the water was measured to keep it constant. The distance of the lamp was measured to the correct length away from the plant in the beaker and the time was recorded and kept at the same time
To attain the accurate results I used the following equipment:
- A ruler to measure the distance between the lamp and the plant.
- A thermometer to measure the temperature of the water to see if it was kept constant for a fair test.
- A stop watch so that every experiment was done at the same time
- The experiment was done three times
- The same amount of sodium hydrogen carbonate was added to the water that was measured using a spatula.
I did this investigation safely by not touching the lamp with wet hands, as this would have given me an electric shock, which could put my life at risk. I also made sure that the thermometer could not fall of the table causing it to break.
Improvements to this investigation
If I were to do this experiment again, I would improve it by allowing more time for the investigation to take place, so that more results will be colleted and that plants need more time to adapt to their surrounding. It will be measured every hour. I would also put scales on the test tube so that the volume of the oxygen bubbles would be measured.
Further investigations
Now that I done this investigation on effect of the amount of light intensity on the rate of photosynthesis, I could also find out about the amount of water given to the plant, the amount carbon dioxide or the temperature the plant is kept in. I would also find a number of plants that have the same number of leaves on them. To extend this, the plants will have the same surface area on the leaves. This would be an investigation to see whether a large surface area speeds up photosynthesis.
