Which of the following instruments did scientists use to observe cells and formulate the cell theory?

a: magnifying glass
b: microscope
c: peice of glass
d: eyeglass lens

How are carbon dioxide emissions affecting the earths natural cycle of temperature change? plz apex

If someone could do the first couple, just so i can see how it's done that would be great! 20 points. complete a dichotomous key for the 10 leaves on the common leaves sheet. the chart provided here allows for 11 pairs of statements. depending on how you build your dichotomous key, you may or may not need all of them, or you may need to add some.

Multicellular organisms use cell division, mitosis, for growth and the maintenance and repair of cells and tissues. single-celled organisms may use cell division as their method of reproduction. regardless of the reason for mitosis, the process ensures genetic continuity. what is the step in the cell cycle that ensure genetic continuity?