All science involves observation.
Hmm, learning about this what a while back, but i would say (1)
Answer:
Common examples include carbon, sulfur, oxygen, iron, copper, aluminium. Elements are represented by symbols. Compounds are substances made from atoms of different elements joined by chemical bonds. They can only be separated by a chemical reaction.
Explanation:
Substances can be categorised as either elements or compounds. Both of these are made up of atoms, the only difference is an element is made of one type of atom whereas compounds are made of two or more different types of atoms.
I'd say, ina general way, that the most imporant cells in defense against parasitic organisms are definitely white blood cels, the cells responsible for defeating antigens, pathogens and deseases.
Although these might be the most important ones in that specific task (defending against parasitic organisms), all the cells in the immune system, along with other non-cell things are important, since they all play a specific role indispensable in our immune system.
Hope it helped,
BioTeacher101
