Dutch elm disease spread more rapidly in the United States than in Europe because of the 1. practice of planting elms in monoculture 2. plentiful breeding sites for beetle vectors due to elm phloem necrosis 3. narrow genetic base of susceptible American elm trees 4. none of the others 5. all of the others

answer by yourhope:

hi! : )

in which structure in the nucleus are ribosomes made?

b) nucleolus!

: )

the relative atomic mass of an element is the mass of one atom of that element, relative to 1/12th of the mass of a  1212c atom. to convert to an absolute mass in kg, it is necessary to multiply by  1.661×10−271.661×10−27.

the relative atomic mass is roughly equal to the number of neutrons, plus the number of protons, in the nucleus of the atom.

for elements with more than one stable isotope (different types of nucleus with different numbers of neutrons but the same number of protons), the quoted mass is usually the average mass, weighted by the relative abundance of the different isotopes.