Answer:
individuals adapt to their environments and, thereby, evolve
Explanation:
Mitochondria. The mitochondria has a variety of different functions and is therefore essential for the cell's productivity.
Hope this helps, if not, comment below please!!!
Answer:
1) Recursive definition: 
2) At the beginning of the 4th interval
Explanation:
1)
The initial population of the bacteria at time zero is

Here we are told that the reading is taken every two hours; we call this time interval "n", so

And also, after every time interval n, the number of bacteria has tripled.
This means that when n = 1,

And when n=2,

Applied recursively, we get

And substituting p0,
(1)
2)
Here we want to find at the beginning of which interval there are

bacteria.
This means that we can rewrite eq.(1) as

By simplifying,

Which means that

However, this means that the number of bacteria is 1,350,000 after 3 time intervals; therefore, at the beginning of the 4th interval.
Nothing really big... It floats because of density not surface tension.
But You can try and discover what will happen. :)
( P.S if you'll drop soapstone it will probably create nice waves... )