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Unformatted text preview: c arotenoids found in plants (green and y ellow lines ). Rec all that an abs orption s pec trum s hows how
effec tiv ely a pigment abs orbs the different wav elengths of light. Notic e that anthoc y anin abs orbs the mos t light in the green region
of the v is ible s pec trum.
The other graph s hows an ac tion s pec trum for the anthoc y aninc ontaining leaf. The ac tion s pec trum illus trates the wav elengths
that driv e photos y nthes is . Notic e that the peak in the anthoc y anin abs orption s pec trum does not appear in the ac tion s pec trum;
anthoc y anin does not driv e photos y nthes is ev en though it abs orbs photons from the s un. ANSWER:
The alga abs orbed the s ame number of photons at eac h wav elength (c olor).
Ev ery photon abs orbed by the alga was us ed to driv e ox y gen produc tion by the alga.
The dis tribution of c hloroplas ts within eac h algal c ell was approx imately the s ame.
The number of bac teria c lus tered at eac h wav elength (c olor) was approx imately proportional to the amount of ox y gen being produc ed by that
portion of the alga. Correct
For Engelmann to be able to draw meaningful c onc lus ions from his ex periment, he had to as s ume that the number of bac teria at any loc ation on
the s lide was proportional to the amount of ox y gen produc ed by the alga at that loc ation. If this were not the c as e, the dis tribution of the bac teria
around the alga would be of no us e in determining the amount of photos y nthes is that oc c urs at eac h wav elength.
Similarly , it was nec es s ary for Engelmann to as s ume that the dis tribution of c hloroplas ts among the c ells in the algal filament was approx imately
equal. Fewer c hloroplas ts in one c ell c ompared to another would mean a lower potential for ox y gen produc tion at any c olor. Engelmann’s
mic ros c ope was s uffic iently powerful to s ee that Cladophora c ells c ontain many s mall c hloroplas ts that were nearly uniform in their dis tribution
within and between c ells .
In c ontras t, Engelmann did not as s ume that the alga abs orbed the s ame number of photons at eac h wav elength. In fac t, mos t photos y nthetic
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This document was uploaded on 02/17/2014 for the course BIOCHEMIST 2550 at Ohio State.
- Spring '14