Rate Of Photosynthesis In Elodea Essay, Research Paper
Investigation into the factors that
affect the rate of photosynthesis in Elodea 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 provide food.? Cells
in the root or stem can use the glucose to make energy, if the plant does not
need to use all the glucose immediately then it is stored which is difficult
because glucose is hard to store in water.?
Plants solve this problem by joining hundreds of glucose molecules
together to make starch.? Starch does
not dissolve in water very well so it makes a better food store. ? Photosynthesis takes place
mainly in leaves and depends on an important green pigment called chlorophyll,
which is found in chloroplasts.? To
obtain the most sunlight as possible, leaves have a large surface area and the
more sunlight the plant receives, the better it can photosynthesize.? Chloroplasts are found in palisade cells in
large numbers and to allow as much light to get in as possible, the cells are
arranged like a fence.? This helps the
energy entering the surface of the leaf to travel a long way through the
palisade cells. ? Glucose can provide energy or
carbon, which can manufacture other molecules in the plant.? Which can make new living matter and this is
called biomass.? The chemical equation for
photosynthesis is: ??????????? Carbon dioxide +
Water??? =?? Glucose and Oxygen??????????? 6CO2? +?
6H20? =? C6H1206? +? 6O2Key Factors:? CO2 is vital in photosynthesis because the plant takes in
CO2 from the air and joins with water molecules to make glucose.? The CO2 comes in through the stomata pores
on the surface of the leaf and only 0.03 % of the air around is CO2 so it?s
pretty scarce.Temperature has to be kept at a certain level because if it gets
too hot, about 45`C then the enzymes in the chlorophyll will be killed and
photosynthesis will stop altogether.? If
the temperature is too cold then temperature becomes a limiting factor and the
enzymes will stop working.Light As chlorophyll uses light energy to perform
photosynthesis, it can only do it as fast as the light is arriving.? Chlorophyll only absorbs the red and blue
ends of the visible spectrum but not the green light in the middle, which is
reflected back.? If the light level is
raised the rate of photosynthesis will increase steadily but only to a certain
point.Water is important because it is needed
to join with CO2 molecules to make glucose and the amount of chlorophyll needs
to be enough so that the plant can photosynthesize to the best of its
abilities. Investigation Prediction I predict that the plastic sheets
coloured green, yellow and orange will produce the least amount of bubbles
because the light will be transmitted.?
Whereas placing red and blue sheets in front of the Elodea will result
in the greatest amount of bubbles because the light is absorbed.? Certain colours of light can limit the rate
of photosynthesis depending on how well it is absorbed into the plants
chlorophyll to photosynthesize.? Also
the wavelength can change the rate of photosynthesis.? If the lamp supplying heat for the plant were placed twice as far
away, I predict that there would be half as many bubbles.? Also if it were moved twice as far closer
then there would be twice as many bubbles.?
This is backed up with knowledge from previous experiments and ones done
by other people and scientific understanding.Diagram ??????????????????????????????????????????????????????????????????????????????????????????????? ???? Previous experiment Method ? For our experiment we chose as accurate
equipment as possible to give us the most accurate results.? The equipment is as follows:? 1 lamp ????????????????????????????????????????????????????????????????????????????????????????????????????? A boiling tube ??????????????????????????????????????????????????????????????????????????? A
small piece of Elodea ??????????????????????????????????????????????????????????????????????????? Plastic
sheets of different colours ??????????????????????????????????????????????????????????????????????????? A
beakerThe boiling tube was filled
with water and the Elodea placed in.?
The boiling tube was placed i
length away.? He plastic sheets were individually
wrapped around the beaker with an elastic band.? For every new plastic sheet we counted the number of bubbles each
time for a minute.? It was important to
keep the experiment the same each time to ensure it was fair test for example:
The lamp stayed the same distance from the beaker, we used the same plant each time
and the plastic sheets were all the same size.?
The experiment was repeated three times and the results were averaged to
ensure they were regular and as expected.?
Results were recorded each time and patterns observed.? Previous results for an experiment of this
kind have been recognized and compared.?
Throughout the experiment we made observations for a number of
distinctive things:???????????????????????????????????????????????? ??????????????????????????????????????????????? ·?? Increase/Decrease in bubbles??????????????????????????????????????? ·?? Temperature Increase/Decrease ·?? Change in Elodea ·?? Size of bubblesVariables include:????????? ·?? Length of Elodea ·?? Amount of water ·?? Distance of lamp ·?? Size of boiling tube ·?? Transparency of sheets ·?? Time spent countingChanging either of the variables would have had effects on the end
results; we kept ours all the same each time to ensure a fair test. Results Coloured sheet Red Orange Yellow Green Blue White No. of bubbles 50 5 1 4 39 17 Repeat 1 45 2 0 0 41 10 Repeat 2 47 1 1 0 35 12 Average 47.333333 2.6666666 0.6666666 1.3333333 38.333333 13 As predicted, the results conclude that using sheets with colours near
the red and blue end of the spectrum produce a higher amount of bubbles than
those near green.? Thereby proving that
photosynthesis is increased with certain colours of light.Conclusion/Evaluation? In observation of the results, I have seen how the rate of
photosynthesis in the Elodea has been affected by the various factors.? In reference to the prediction, I was
correct in that the red and blue coloured sheets produced the highest rate of
photosynthesis, whereas the sheets, which were green and yellow, resulted in
the least bubbles.? I feel that we had
taken enough measurements to be sure of a fair test as the experiment was
repeated several times so.? Each plastic
coloured sheet we used had the same time, and variables as the others so we
obtained precise results for every test.?
We did not find anything, which stood out too much from the pattern
except that the red plastic sheet, when used resulted more bubbles generally
than the blue sheet.? This shows that
chlorophyll absorbs red light more easily than blue.? We acquired similar results with each repetition and found ours
to be similar to previous experiments.?
The Elodea produced more bubbles with sheets at each end of the spectrum
because the chlorophyll in the plant absorbs all the colours but transmits
green.? When the light is absorbed the
plant converts it into energy to photosynthesize.? The more light energy it receives the better and faster it can do
this so when the sheets near the blue and red parts of the spectrum are held in
front of the Elodea it absorbs the light and can photosynthesize better.? If plastic sheets are held up which are have
a colour near the green part of the spectrum then the light will be transmitted
and the plant will not be able to photosynthesize as well.? In this experiment we have covered the main
colours of the visible spectrum and they are sufficient to produce the results
that we are looking for. If we were to repeat the experiment then there are several ways we could
improve it.? For example to get around
the problem of the heat from the lamp producing more bubbles then a thick glass
panel could be placed in the middle to prevent any heat reaching the Elodea.? To improve the accuracy of counting the
bubbles, you we could only count the ones, which are a certain size, and only
the ones coming from the very end of the Elodea.? If there were lots of people counting the bubbles and the results
averaged then that would be a more accurate way of obtaining the information necessary.? To extend the investigation you could change
certain variables for example the type of plant that you are using to count the
bubbles from.? You could try an entire
species of plant and see if the results are similar for every type. You could
use different chemicals in the water each time to see which chemicals result in
the greatest rate of photosynthesis.