When cells take on specific structure and function, this is called?

In this experiment you were asked to present three possible mechanisms. describe those mechanisms here and include drawings of those mechanisms. how will the bromination of trans-cinnamic acid and trans-stilbene allow you to distinguish between the three possibilities? what would you expect to find in your data in each scenario?

The table shows dates and appearance of index fossils. which rock layers can be dated most precisely? a) a layer containing both a fossil 4 and a fossil 3 b) a layer containing both a fossil 2 and a fossil 3 c) a layer containing both a fossil 1 and a fossil 4 d) a layer containing both a fossil 1 and a fossil 2

Ihave no idea how to solve these. plus there's another question that is 2) a 10 kilogram meteorite is collected in space and brought back to earth. it is composed of 1.25 kg of uranium-238 and 8.75 kg of lead-206. how many u-238 half lives have passed? what is the approximate age of the meteorite?