Describe the similarities and differences observed among phototrophic bacteria
What will be an ideal response?
All major groups of bacteria contain phototrophic bacteria, which includes the cyanobacteria and the green and purple phototrophic bacteria. All phototrophic bacteria are structurally similar in that they use photosynthetic lamellae that contain the photosynthetic pigments necessary for photosynthesis. However, the type of photosynthetic pigment used differs among these groups. For example, cyanobacteria contain chlorophyll a, whereas the green and purple photosynthetic bacteria use bacteriochlorophyll. The type of photosynthesis differs as well: cyanobacteria engage in oxygenic photosynthesis, whereas the green and purple bacteria are anoxygenic. Finally, most phototrophic bacteria are autotrophic, although they differ in the ways they obtain electrons for the reduction of CO2; most notably, the sulfur bacteria oxidize hydrogen sulfide to obtain electrons for CO2 reduction.
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Consider a biochemical pathway that branches to form two different products. If the end product of one of the branches is present in a large amount, at what point would the pathway be regulated to ensure adequate production of the end product of the alternative pathway while slowing or stopping production of the product already present in excess?
A. At the last step in the pathway to the alternative product still needed B. At the last step in the pathway to the product in excess C. At the point where the two pathways branch D. At the very first step in the entire pathway
Axons of olfactory receptors extend from the nose to the:
a. mouth b. underlying connective tissue c. spinal cord d. brain e. ganglia
The karyotype in the image below is that of a _____
1.normal female
2.male with Down syndrome
3.normal male
4.nonhuman mammal
The significance of the Hershey and Chase
experiments in which 32P and 35S were used is that a. DNA labeled with 35S and proteins labeled with 32P can be traced in the course of an experiment. b. they demonstrated that DNA labeled with 32P is transferred from the bacteriophage to the virus. c. they established that proteins labeled with 35S become deactivated and unable to be transferred. d. they demonstrated that bacteriophages transfer their DNA, not their protein coats, into their hosts. e. DNA may be the hereditary material; although, bacteriophages transfer both DNA and proteins into their hosts.