The substance dichlorophenyldimethylurea (DCMU) is an herbicide thatinhibits photosynthesis by blocking electron transfer between plastoquinones in photosystem II.(a) Would you expect DCMU to interfere with cyclic photophosphorylation?(b) Normally, DCMU blocks O2 evolution, but addition of ferricyanide to chloroplasts allows O2 evolution in the presence of DCMU. Explain.

The substance dichlorophenyldimethylurea (DCMU) is an herbicide thatinhibits photosynthesis by blocking electron transfer between plastoquinones in photosystem II.(a) Would you expect DCMU to interfere with cyclic photophosphorylation?(b) Normally, DCMU blocks O2 evolution, but addition of ferricyanide to chloroplasts allows O2 evolution in the presence of DCMU. Explain.

Biology (MindTap Course List)

11th Edition

ISBN:9781337392938

Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. Berg

Publisher:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. Berg

Chapter9: Photosynthesis: Capturing Light Energy

Section9.2: Chloroplasts

Problem 2C: What is the significance that the combined absorption spectra of chlorophylls a and b roughly match...

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1) Dichlorophenyldimethylurea inhibits photosynthesis by blocking electron transfer between the plastoquinone in photosystem II. a) Would you expect this to interfere with cyclic photophosphorylation? b) This herbicide normally stops O2 evolution, but if we add ferricyanide to the chloroplasts, O2 evolution continues. Why might this be the case?
The substance dichlorophenyldimethylurea (DCMU) is an herbicide thatinhibits photosynthesis by blocking electron transfer between plastoquinonesin photosystem II.(a) Would you expect DCMU to interfere with cyclic photophosphorylation?(b) Normally, DCMU blocks O2 evolution, but addition of ferricyanide tochloroplasts allows O2 evolution in the presence of DCMU. Explain.
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In 2010, a bew form of chlorophyll (chlorophyll f) was discovered in cyanobacteria assemblages of stromatolites growing in Shark Bay, Australia. Chlorophyll f has been isolated. and scientists are investigating the structure and function of this pigment. Based on your understanding of photosynthesis, how would you determine the wavelengths of light the pigment absorbs? How would you determine if this pigment plays a role in photosynthesis? (Hint: Think about the overall equation for photosynthesis.)
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What is the significance that the combined absorption spectra of chlorophylls a and b roughly match the action spectrum of photosynthesis? Would photosynthesis be more efficient if their individual absorption spectra coincided exactly?
There are two photosystems ( I and II) involved in the light-dependent reactions of photosynthesis. What is the functional difference between these two photosystems?
In photosynthesis, contrast the light reactions with the light independent reactions, in terms of goals, inputs, and outputs of each. Spatially where do they take place (which parts of the chloroplast)? (Optional, for further discussion: Could there be light reactions without light-independent reactions, or visa-versa?)