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Investigation Into The Factors That Affect The

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 in the beaker and the lamp placed at a set

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.

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