Photosynthesis Practical

Photosynthesis Practical

Introduction- Photosynthesis is the chemical process, which takes

place in every green plant to produce food in the form of glucose.

Plants use the suns energy to join together water and carbon molecules

to make the glucose, which is sent around the plant to be used in

respiration.

6CO + 6H O ® C H O + 12O (in the presence of light energy and

chlorophyll)

Aim- The aim of the experiment is to determine what effect light

intensity has upon the rate of photosynthesis of Canadian Pondweed

(Elodea).

Prediction-I think that as the light intensity increases, the rate of

photosynthesis will as well. This is because plants need light energy

to photosynthesise, to join water and carbon molecules together to

form glucose. If more light energy is available to the plant, then it

will be able to photosynthesise at a faster rate. The light provides

energy for the reaction to take place, and so if a plant has more

light then it should have more energy to use in the reactions, and the

rate of reaction should become faster. After a certain point, the rate

of reaction will stop increasing and become constant. This will either

be because another factor (such as Carbon Dioxide or temperature) has

become limiting, or in the shortest supply, and preventing the rate of

photosynthesis from becoming any faster, because even if the plant had

the greatest light intensity possible, it would not be able to

photosynthesise quicker if there wasn't enough CO2 for it to, or if it

wasn't warm enough. However, if neither of the factors are limiting,

then the reason for the rate of PNS becoming constant would be because

the plant simply cannot photosynthesise at a faster rate.

Method- I will prepare the apparatus as in my diagram, but leave out

the pondweed, funnel, test tube, water and sodium bicarbonate. The

beaker should be as close to the plastic screen as possible. Then I

will fill the beaker with 200ml of water and 1.5g of sodium