This is the boss. No calculator — every number on this paper is a power of two, and powers of two are what your head is for. One incubator, two clocks running at once: a culture DOUBLING on one schedule while its marker dye HALVES on another. Both laws are the same law with the factor flipped, and this plate is where you prove you know it.

Every answer feeds the next: doublings elapsed, then the population, then the dye that survived, then the ratio the lab actually reports. Write each line down as you go — one early slip rolls all the way to the bottom of the page, and the finish screen will show you exactly where it started.

Then a bonus mark that is not a calculation but a DECISION: two jars, one with a head start and one with a faster doubling time. Head starts add once; doubling times compound forever. Which one has won by the time the incubator opens is the whole question — and it depends on the clock. 5★ under par here is the chapter crown. Clock in.