Does the amount of light affect the rate of photosynthesis?

Question

Im currently studying grade 12 biology and i have to do an extended experimental investigation. I want to prove that deferent amounts of light affects photosynthesis but is this possible to do in a school labitory?? If so, how would i do so??

Answer 1

Yes the amount of available light does affect the rate of photosynthesis although different plants are adapted to different amounts of light (plants living on the forest floor, for example, are adapted to use less light than trees or taller plants that can get more direct sunlight).

Proving this in a school lab is a bit more difficult. One of the classic ways is to measure the amount of carbon dioxide taken up and synthesised into glucose (or starch) but that required that the CO2 included radioactive Carbon 14 - its a fun experiment but not for the school lab!

Basically photosynthesis takes CO2 and turns it into glucose so you will need a means of measuring the reduction in CO2 levels in a sealed container with a plant in it under various strengths of light OR a way of measuring the increase in the amount of glucose in the plant under different light conditions.

Testing for the presence or absence of glucose in a plant is relatively simple in a school lab but it's more difficult to measure the exact amount. Masking leaves on the same plant with various filters will produce different levels of glucose production in that area of the leaf and will also show a decline in the green pigment indicating the reduction in chlorophyll. If you sample the same mass of leaf under different masking conditions then you might just be able to see different results depending on the amount of glucose in that part of the leaf using a standard reagent test for glucose.

Most school lab experiments (like those described below) prove that light is essential for growth (not necessarily for photosynthesis) or stimulates the production of photosynthetic pigments like chlorophyll.

Answer 2

Yes, amount of light affects photosynthesis and the plant(s) will grow less than one(s) exposed to more light. But also, frequency of light affects photosynthesis, so you may want to include in your experiment different wavelengths of light and see the effect. Set up controls and exprimental groups.

Answer 3

Yes it is possible. there are two ways you can do it

1st way put one plant in a cupboard, a second plant on the window sill and a third in the middle of the room where sunlight reaching it is about half the window sill plant

2nd way is have one plant and cover the leaves in different materials, one opaque, one translucent, one semi-translucent, one leaf that has not been covered, etc..

both ways you are looking for the change in colours of the leaves as when photosynthesis occurs, chlorophyll is produced which is green. this experiment can easily be done in a school laboritory

Answer 4

Yes. The amount and quality affects the process.
That is why there are two kinds of photosynthesis. The Light and dark phase...