Scientists are studying the structure and function of Receptor X, a single-polypeptide protein that is found in the membrane around certain types of cells. Receptor X contains no alpha-helices or beta sheets. A specific molecule outside the cells is recognized and bound by Receptor X. The binding of the molecule to Receptor X causes the cells to have a particular response.

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.

1. the energy lost to disorder metabolism     -entropy

2. related to or possessing motion potential     -kinetic

3. all of the chemical reactions in an organism required for maintenance of the processes of life entropy     -metabolism

4. possible; ability to go into action or perform work kinetic     -potential

5. the study of energy and its transformations thermodynamics     -thermodynamics