Identify the effects of the disorders that weaken
the immune system.
School District One decrease in the production of
2. Immune cells mistake healthy cells as
3. Abnormal cells crowd out
steal nutrients.
cells and
4.
The body is susceptible to

answer: atomic mass was originally used to arrange elements on the periodic table, but is no longer used to organize the modern version.

explanation:

originally atomic mass was used to arrange elements on the periodic table from left to right in a row. each column then shows similar properties of elements of a group.

in modern periodic table, the atoms are arranged in increasing atomic number. as atomic number represents the number of protons in an atom which is unique for every atom.