B.
Genetic drift is the change in the frequency of an existing gene variant in a population due to random sampling of organisms.
I Think The answer is c I hope it helps
The correct answer is option B, that is, all living organisms are composed of one or more cells, which came from pre-existing cells.
A scientific theory refers to a well-substantiated illustration of some characteristic of the natural world, on the basis of a number of facts, which have been repeatedly confirmed via the experiment and observation. Such fact-supported theories are not hypotheses, however, are reliable explanations of the real world.
During the late 1830s, the zoologist Schwann and the botanist Schleiden were examining tissues and postulated the unified cell theory. According to the unified cell theory, all the living things comprises of one or more cells, the cell is the fundamental unit of life, and the new cells originate from the pre-existing cells.
Answer:
They are opened either by the binding of ligands or by changes in electric potential across the membrane
Explanation:
Ion channels are the integral membrane proteins that form pores or holes for the transport of specific ions, such as potassium ions (K+), Na+, etc. Most ion channels are selective and allow only a single type of ion to pass through. These ion channels facilitate the diffusion of ions down the concentration gradient and do not require ATP.
Ion channels are mostly gated. Some ion channels open in response to change in the concentration of ions and electric charges across the membrane. Some ion channels open and close in response to the binding of specific molecules called a ligand. For example, binding of two molecules of acetylcholine to the receptor on the motor endplate of a neuromuscular junction opens an ion channel in the ACh receptor through which Na+ can flow across the membrane.
