Excerpts from Photosynthesis Conclusion Sections

Good Excerpts

Note that while none of these quotes would stand alone as a good Conclusion section, a number of these ideas combined together might do quite nicely.

Note how this quote begins to draw conclusions based on the data, and relates the conclusions back to the hypothesis.

This study was conducted to determine a possible relationship between light available to and/or absorbed by the pigments in plants and the rate of photosynthesis in the various colors of light. Data support the hypothesis that some colors of light contribute more to the process of photosynthesis. Elodea isolated in test tubes with specific food colors could only use light that the food coloring did not absorb. The results showed that plants have higher rates of photosynthesis in red and yellow light. The rates of photosynthesis in red and yellow light were considerable higher than those in blue and green, almost twice as high.
[This could have been improved by cited actual numbers rather than just saying they were “twice as high,” or that “data support the hypothesis.”]

Here is a quote that begins to draw some conclusions based on the data:

The wavelengths at which the absorbance of each food coloring peaks are colors which would be unavailable to a plant placed in a solution containing that dye. The green food coloring had peaks at about 400 nm and again at 625 nm. A plant placed in a solution of green food coloring would, therefore, not do photosynthesis well because 400 to 450 nm is where photosynthesis does best. Yellow food coloring also had a high peak at 400 to 450 nm, making the light available in a solution of yellow food coloring bad for photosynthesis. Red food coloring did not have a high peak at 400 to 450 nm, therefore plants in a solution of red food coloring would be expected to be able to do photosynthesis. A solution of blue food coloring would be ideal for the photosynthetic process because, of all the pigments examined, the blue food coloring absorbed the least amount of light at 425 to 450 nm, and thus would allow a plant’s photosynthetic pigments to absorb all that light.


Not So Good Excerpts

Many of these quotes belong in either the Data or the Methods and Materials section,
and then there are others. . .

♦ After testing in the spectrophotometer, the pigments were identified. The spinach absorbed lowest at green, thus reflected green and absorbed the rest of the spectrum. Chlorophyll A absorbed red, blue, and violet, giving off a yellowish-green color. Chlorophyll B absorbed less of red, blue, and violet, but reflected more green. Carotene absorbed blue, violet, and some green, reflected yellow, orange, and red.. . .etc.
[This is really a list of data. How/why are those data significant? Why is which pigment absorbs which color important? How do the absorption maxima for each of the individual pigments correlate to the maxima seen in spinach?]

♦ According to the data, pigments absorb light at different wavelengths. It can be determined from the data that the carotenes absorb the most light at about 450 nm and absorb the least at around 600 nm. Xanthophyll was also found to absorb best at about 450 and least between around 550 and 600 nm. . . etc.
[Again, just a list of data.]

♦ The pigments from the spinach stripe were separated according to the color spectrum. The color spectrum starts at red going down to purple, as did the pigments from orange to green.
[If the first sentence was true, it would belong in the Methods and Materials section. If the second sentence was true, it would belong in the Literature Review section. Neither of these say anything about conclusions that were drawn based upon an analysis of the data.]

♦ The use of a spectrophotometer is to find different absorbance levels at different wavelengths. A spectrophotometer was used during this experiment to do just that. Absorbance levels for different pigments in plants, and different food colorings, was taken, recorded, and observed. Absorbance of light in pigments can be compared with the absorbance of light in food coloring. The red and blue food colorings have a high absorbance where plants need it the most. Therefore, blue and green light is absorbed by the pigments and used more by the pigments.
[The first sentence is not necessary for a scientifically-literate reader. The next couple of sentences (without the grammatical errors) belong in the Methods and Materials section, and the last couple of sentences, if they were true and made sense, would probably belong in the Data section. Note the incorrect verb usage in blue and green light is. . .]

♦ In Elodea, the red and yellow light has a higher absorbance then the green and blue. White has a 100% absorbance, and red is next. . .
[We did not measure the amount of light absorbed by Elodea. There is no such color as “white.” White light is the appearance to our eyes of a mixture of all of the visible colors, and plants do not absorb/use all of those colors equally well – that was one of the main points of the whole experiment.]

♦ Pigments, such at carotene’s, xanthophylls, and chlorophyll B, have high absorbance levels at 450nm. Chlorophyll A has its highest peak at 425nm. Carotene has its lowest peak at 600nm, xanthophyll at 450nm, and Chlorophyll A & B have a lowest peak at 525nm. . .
[Again, just a list of data. Note the incorrect usage of “–’s” and incorrect spacing between numbers and units (“450nm” should be “450 nm”). “Lowest peak” is not a good way to describe carotene’s absorption minimum at 600 nm – that term implies a peak that is the lowest of those present, not a “minimum” or “trough” or “valley,” as really occurred at that point. There are grammatical errors here, too.]

♦ Green and yellow food coloring has its high peak at 625 and 400nm. This is where plants don’t need any absorbance help, and where they do need it, green and yellow have low absorbance. . .
[The first sentence has a grammatical error that turns it into nonsense. Regarding the second sentence, plants do not utilize any “help” from food coloring.]


Copyright © 1998 by J. Stein Carter. All rights reserved.
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