As an onion undergoes mitosis, an onion cell will make a copy of its genetic material which leads to the development of an identical daughter cell. Which part of an onion’s
cells contains the genetic material needed for mitosis to produce these identical
daughter cells?
F Chromosomes within the nucleus
G Chromosomes within the endoplasmic reticulum
H Ribosomes within the cytoplasm
J Chloroplasts

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.

answer: substrate concentration. enzymes work best when there is a high enough substrate concentration for the reaction they catalyse.