I think you forgot to post the picture needed for the question. However, after some research I found it online. The picture should show a circle with areas for bacteria growth, area of no growth (ZOI) , and antibiotic disc A. The diameter in mm of the ZOI for disk A will be 13 mm.
There are 640 muscles......
Nitrogen must be converted into nitrates before organisms can use it. If soil lacks nitrogen fixing bacteria, then it has few nitrates for the plants to take in.
A mixture of minerals that makes up the earths crust.
I don see the question if there is one can you explain and ill edit my answer to best fit