The relationship between photosystem I (PSI) and photosystem II (PSII) is correctly described by which of the following statements?
A) PSI precedes PSII in photosynthesis.
B) Electrons are excited by PSI or PSII, but not both.
C) Chlorophyll molecules in the reaction centers of PSI and PSII are designated P700 and P680, respectively, to reflect the wavelengths of their light absorption maxima.
D) PSII was discovered before PSI.
E) Only PSI contains a special pair of chlorophyll a molecules.
Answer: C
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Endolithic phototrophic communities are MOST common in ________ environments
A) dry B) hot C) humid D) windy
How do anoxygenic phototrophs benefit from possessing accessory pigments that allow light to be harvested at deeper areas of a fluid environment?
A. This allows even anaerobic microbes to conduct photosynthesis, as they can harvest light energy in the deeper areas where oxygen won't be present. B. The cells can use wavelengths of light that havenotbeen absorbed (filtered out) by the photosynthetic organisms closer to the surface of the fluid. C. They don't have to compete with other cells that utilize oxygen in the upper levels for the scarce nutrients in the fluid environment. D. This allows even anaerobic microbes to conduct photosynthesis, as they can harvest light energy in the deeper areas where oxygen won't be present AND can use wavelengths of light not absorbed (filtered out) by the photosynthetic organisms closer to the surface of the fluid. E. This allows even anaerobic microbes to conduct photosynthesis, as they can harvest light energy in the deeper areas where oxygen won't be present, use wavelengths of light not absorbed (filtered out) by the photosynthetic organisms closer to the surface of the fluid; AND don't have to compete with other cells that utilize oxygen in the upper levels for the scarce nutrients in the fluid environment.
Explain how a complex trait, such as eyes or the ability to fly, can evolve by incremental modifications over time
What will be an ideal response?
Eukaryotic cell nuclei contain genes that are
a. primarily of eukaryotic origin. b. primarily of archaebacterial origin. c. partly archaebacterial and partly eubacterial in origin. d. derived from neither archaebacterial nor eubacterial cells.