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.
The answer would be letter B.
Answer:
Alleged father #2
Explanation:
Normally alleged father #2 has in common with the child the gene that every man would, this would not be evidence that he is the father. But, in the case of finding a really strange trait with the kid that would not be coincidence, in that case it would be a high probability of paternity. This genes need to be analyzed in the nucleus of the cells where the units of heritage are present making us unique individuals according to the infinite combinations that ca be present in our DNA.
For the first question, I would say a line graph. And the one about the human heart, I need some more information.