4. To determine the frequency of ala mutants a fluctuation test was done using 30 tubes with a final concentration of 108 bacteria each. From
each tube 0.1 ml of culture was plated on medium that selects for ala
mutants. 27 of the tubes yielded ala mutants but 3 of the tubes yielded
no mutants. Based upon these results, use the Luria-Delbruck
calculation to determine the mutation rate to ala.

explanation:

b,bacteria convert nitrates

into nitrogen gas.

d,plants and animals take in

and use nitrogen compounds.

e,bacteria break down waste    

products and return nitrogen  

to the soil.

a,bacteria convert atmospheric

nitrogen to ammonia.

c,bacteria convert ammonia

to nitrites and nitrates.

it provides an alternative energy pathway for the reaction to proceed.

a catalyst is a substance that speeds up the rate of a chemical reaction but is not consumed during the course of the reaction.

catalysts increase the rate of reaction without being used up. they do this by lowering the activation energy needed. with a catalyst, more collisions result in a reaction, so the rate of reaction increases. different reactions need different catalysts.

a catalyst works by providing an alternative reaction pathway to the reaction product. the rate of the reaction is increased as this alternative route has a lower activation energy than the reaction route not mediated by the catalyst.