In your own words explain how the process of radioactive decay is used to accurately date fossils

Radioactive elements or isotopes are atoms which release radiations over time and this cause decrease in their amount and convert to other isotope. This is also known as radioactive decay.

Half life: Half life of an radioactive element is the time, after which the amount of element remains half.

To accurately date fossils, we should know the half life of an element.

In radioactive decay one isotope change to other by emitting radiations with time. We check the amount of secondary isotope and then relate it to half life of element to know the time that how much time take to make this secondary element.

cells use diffusion to get substances in and out of themselves. that diffusion will occur across the cell membrane or the outer covering of the cell. because we are talking about the surface of the cell, surface area and volume are  important factors here. as a cell increases in size, its surface area and volume increase as well.  we call that the surface area to volume ratio (sa: vol).  but the catch is that  volume increases at a greater rate than surface  area. in other words, as a cell gets bigger, the sa: vol gets smaller. so a really small cell like bacteria is mostly cell membrane (surface) with very little contents (volume). a really big cell like an egg, is mostly insides with a super thin membrane. so what ends up happening is that the cell cannot efficiently diffuse all of the stuff it needs in/out to survive. therefore cell size is limited to about 100mm. so how do we make organisms bigger than 100mm? cells divide! by dividing and becoming multicellular, organisms are able to grow!   check out the diagrams i attached to see the effect of sa: vol. i hope this ! good luck!