Answer:
The above paragraphs describes that how salt- and fresh-water fish regulates their osmoregulation. Hence, the correct answer would be c. have adapted to deal with osmosis.
Osmosis is the process by which solvent's molecule move from region of low concentration (hypo-tonic) to the region of high concentration (hyper-tonic) through a semi-permeable membrane.
In sea-water fishes, the body fluids are hypo-tonic to the surrounding water and thus water is kept moving out of their gills. In order to prevent the excess water loss they need to drink water constantly and excrete concentrated urine.
In contrast, fresh-water fishes body fluids are hyper-tonic to surrounding water and hence, water keeps entering in their body through gills. So, in order to prevent excess dilution they absorb salt from surrounding with the help of gills and also their bodies reabsorb salt from urine.
When lactose is not present, what happens to E. coli is that the genes that produce the enzymes needed to break down lactose are not expressed. The correct answer is B.
The concentration gradient of K+ would increase. This would give a great driving force for the higher concentration of the K+. Once absorbed in the blood, it would diffuse through the cell's membrane. Since K+ is an ion, it would increase the membrane potential of the cell.
The water will flow out of the cell and into the area with more solutes.
