Biochemistry: Concepts and Connections (2nd Edition)
2nd Edition
ISBN: 9780134641621
Author: Dean R. Appling, Spencer J. Anthony-Cahill, Christopher K. Mathews
Publisher: PEARSON
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Chapter 15, Problem 6P
The substance dichlorophenyldimethylurea (DCMU) is an herbicide that inhibits photosynthesis by blocking electron transfer between plastoquinones in photosystem ll.
a. Would you expect DCMU to interfere with cyclic photophosphorylationQ
b. Normally, DCMU blocks O2 evolution, but addition of ferricyanide to chloroplasts allows O2 evolution in the presence of DCMU. Explain.
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You performed an experiment on photosynthesis on Elodea, using bromothymol blue as an indicator forpH. Your two light conditions were red light and blue light. You found that in blue light, your solutionturned a nice cobalt blue, and in red light it turned green.a. What can you conclude about the efficiency of photosynthesis in Elodea regarding those twowavelengths?b. What would your conclusion be if your negative control (no Elodea in white light) turned greenalso?
The substance dichlorophenyldimethylurea (DCMU) is an herbi-
cide that inhibits photosynthesis by blocking electron transfer
between plastoquinones in photosystem II.
(a) Would you expect DCMU to interfere with cyclic photophos-
phorylation?
(b) Normally, DCMU blocks Oz evolution, but addition of ferri-
cyanide to chloroplasts allows Oz evolution in the presence of
DCMU. Explain.
The substance dichlorophenyldimethylurea (DCMU) is an herbicide that in-
hibits photosynthesis by blocking electron transfer between plastoquinones
in photosystem II.
(a) Would you expect DCMU to interfere with cyclic photophosphorylation?
(b) Normally, DCMU blocks Oz evolution, but addition of ferricyanide to
chloroplasts allows O, evolution in the presence of DCMU. Explain.
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Biochemistry: Concepts and Connections (2nd Edition)
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