Quiz_2_answers'07 - BIO SCI 104 SPRING 2007 Major Quiz II...

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BIO. SCI. 104 SPRING 2007 Major Quiz II Name: __________________________________ Date: _________________________________ ____1. The data table below gives the results of feeding trials using pairs of mutant strains of a bacterial species grown on a nutrient agar medium. Each mutant strain alone is unable to make the end product of a biosynthetic pathway because it cannot perform one of the reactions. Strain Fed (+) or Not Fed (-) Potential Feeder Strain 1 2 3 4 5 6 1 2 + + + + 3 + + + 4 + + + + + 5 + + + 6 + + + + A. Which strain cannot feed any other strain (if none, answer none)? ___1___ B. Which strain is not fed by any other strain? ____4__ C. Which pairs of strains show mutual feeding?__ 5 and 3; 5 and 2; 3and 6; 6 and 2_ D. Select the pathway below that conforms to the results of the feeding trials. (Uppercase letters represent intermediate compounds in the pathway.) PATHWAY 3 E. Circle the number of the pathway you have selected. Make a vertical mark through the arrow representing each reaction and write, above the mark, the number of the strain in which that step is blocked. A. A B E F D G End Product Pathway 3 C 2. . A certain species of bacteria uses the biochemical pathway shown below to make a green pigment. Two different mutant strains of the bacteria are unable to make the pigment when 6 5 4 1 3 2 A C D E End Product B Pathway 3 F G
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they are grown separately on nutrient agar. Each strain has only one step (reaction) blocked as shown on the diagram. G A B E C D H F 1 2 J Green Pigment 1. When strains 1 and 2 are grown side-by-side, but not touching each other, in a feeding trial, which of the following is a possible result? (Circle the letter of the answer.) a) Only strain 1 will produce green pigment. b) Only strain 2 will produce green pigment. c) Both strains will produce green pigment. 1. a) Only strain 1 will be green. 2. Briefly explain your answer. Both strains can make the green pigment if they have intermediates D and J. Strain 2 can make intermediates D, E and H. If D, E and H can diffuse to strain 1, it can make J and then make the green pigment. Neither strain 1 nor strain 2 can make J, so strain 1 can not feed strain 2.
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Quiz_2_answers'07 - BIO SCI 104 SPRING 2007 Major Quiz II...

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