Las estructuras que facilitan la union de las venas y arteriasel intercambio gaseosos entre los dintistos tejidos y la sangre que circula se denominan

Explanation is in the file

cutt.ly/nz6VGda

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.

the index of refraction of the second medium is higher. i just took the test trust me !