Density-dependent inhibition is a phenomenon in which crowded cells stop dividing at some optimal density and location. this phenomenon involves binding of a cell-surface protein to its counterpart on an adjoining cell's surface. a growth inhibiting signal is sent to both cells, preventing them from dividing. certain external physical factors can affect this inhibition mechanism. select the statement that makes a correct prediction about natural phenomena that could occur during the cell cycle to prevent cell growth.

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.