A concentration gradient can be described as a phenomenon by which molecules travels from an area which is highly concentrated to an area which has low concentrations of that molecule.
Answer No 2:
A molecule is said to be diffusing down a concentration gradient when molecule acquire the phenomenon of concentration gradient i.e move from higher concentration to lower concentration. This mechanism is also termed as passive transport. Active transport is the opposite of passive transport. In active transport, molecules move against the concentration gradient i.e from an area of lower concentration to an area of higher concentration.
Because of the difference in the genetic makeup of those with the beak shape, their population evolves to a higher level of adaptation. I think it should be fewer mutated.
A control group setup in an experiment is used to see if there are other variables in play during the experiment. Say I was to test which type of blood is a shark's favorite, my control would be putting red paint in one of the set ups to see if the shark is just interested in the red color of blood, instead of the other types of blood.
In 1992 the trout population was 4. Thus, initial population of trout is 4. In 1993 it grew to (4)², that is 4×4 = 16, in 1994 it grew (4)³, that is 4×4×4 = 64. This shows the trout has grown exponentially. Therefore, the trout population will be (4)⁴, that is 4×4×4×4 = 256.