When games and competitions are held at high altitudes, athletes must specially train to postpone their cells from switching to

anaerobic cellular respiration

Explanation:

Given that anaerobic cellular respiration does not require oxygen, and when games and competitions are held at high altitudes, the human body system ATP demands exceed the available oxygen.

Hence, to cope and survive in this situation, the athletes must specially train to postpone their cells from switching to anaerobic cellular respiration. This helps the athletes to last longer and withstand the temperature.

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.

step 1: nitrogen fixation- conversion of atmospheric no₂ into forms useful to plants by lightning, bacteria, and cyanobacteria.

step 2: nitrification-process of converting ammonia to nitrite or nitrate.

step 3: assimilation-plant roots absorb new form of nitrogen.

step 4: ammonification-conversion of organic nitrogen to ammonia by bacteria involved in decomposition.

step 5: denitrification-bacteria turns the decomposed matter back into n₂o, which is released into atmosphere; repeat cycle.