Which statement is true about the cell theory? it is based on observation. it is based on a random guess. it is unchangeable and permanent. it is a claim posed by some scientists.

The cell theory was based on an observation. The cell was first discovered by Robert Hooke in the late 1600s. His discoveries were narrated in detail in his book Microphagia. In the said book, he gave 60  detailed observations of various objects under an uncouth, compound microscope. One of the observations was from a very thin slice of bottle wine cork. Hooke had discovered tiny pores that he later on named as "cell" which came from the Latin word "cella" meaning a small room where monks live. Hooke was neither aware of the real structure of cells nor its functions because, during that time, microscopes had low magnification which prevented him from unraveling other internal cellular components.

An  atom  (ours, not carroll's) consists of a positively charged  nucleus, surrounded by one or more negatively charged particles called  electrons. the positive charges equal the negative charges, so the atom has no overall charge; it is electrically neutral. most of an atom's mass is in its nucleus; the mass of an electron is only 1/1836 the mass of the lightest nucleus, that of hydrogen. although the nucleus is heavy, it is quite small compared with the overall size of an atom. the radius of a typical atom is around 0.1 to 0.25 nanometres (nm), whereas the radius of a nucleus is about 10-6  nm.  *  if an atom were enlarged to the size of the earth, its nucleus would be only 200 feet in diameter and could easily rest inside a small football stadium.read more on -

Apossible long term health effects of stress would be work