Science question: Which beat summarized the scientific process that led to our current understanding of DNA? 1 each scientist made an important but unrelated contribution
2. Scientists built on the previous work of other scientists to make new discoveries
3 and 4 are too long

2

Explanation:

in terms of cells, it exists from previous existing cells, that means scientist are built up by the work of other scientist

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.

the number of protons in the nucleus of a given element. has slight luster and conducts electricity at high temperatures like metal.but like a nonmetal,boron is brittle and does not conduct electricity well at low temperatures. in graphite, carbon is a soft,brittle solid.it is reflective,ductile,or malleable.