Answer:
At least 17 PCR cycles or 16 PCR cycles
Explanation:
As we know -
In one chain of heating and cooling of polymerase chain reaction (PCR), the strands of DNA gets doubled.
The general mathematical representation of this is

where "n" is the number of PCR cycles.
It is given that DNA strands to be produced is 16 times the original quantity of DNA.
So the PCR cycle must be carried out at least 17 times in order to have DNA strand not less than 16 times the original quantity of DNA
Answer: D.) It allows water to resist freezing and thawing cycles.
The ability of the water molecule to absorb and retain heat is called as heat capacity of water, because of this property the temperature of water remains the same for long, irrespective of the external environment. It allows water to resist freezing and thawing cycles because water molecules will resist change in it's temperature. This temperature regulation will prevent instant heating and cooling, hence, will provide suitable environment for the survival of marine organisms.
The correct answer is by using the antagonist.
The antagonist is a molecule that blocks a biological response by binding to the receptor. So, you add antagonists to the receptors you want to determine and see which antagonist blocked the response. By blocking the specific response you can get the answer what receptor it was.
The alula is a small structure that is found on birds. It is located at the joint between the hand wing and the arm wings of birds and it is the freely moving, first digit of a bird's wing. It is normally used by birds in slow flight. In humans, the structure that is comparable to the alula is the thumb.