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.
1. elliptical 2. solar system
Answer: C). A tsunami would decrease abundance by causing physical damage to the organisms and their ecosystems.
An intertidal zone is also known as littoral zone. It is the region which is covers the foreshore and seabed. This region is exposed to the affects of tides. This region is highly vulnerable to tsunamis. The tsunami will disturb the habitat of organisms living in intertidal zone. Therefore, will result in decrease in abundance of aquatic organisms.
The cell keeps molecules balanced inside and out hope i was right have a very nice day
<span>A. Stimulus is the term used to describe what causes organisms to react to their environment. Stimulus is something that can provoke organisms to respond to the world around them. For example, if you put your hand on the stove, the stove is going to be the stimulus for you to get burned and move your hand from it because it will be to hot - that is going to be your reaction to the stimulus. Camouflage is a type of hiding mechanism, parasites are organisms, and homeostasis is equilibrium in an organism. </span>