Answer:
B. retain its urine in it’s blood stream
Explanation:
Sharks are cartilaginous fishes that lives in the ocean. Oceans are always salty, hence organisms need to maintain a salt-water balance between their internal and external environment because of osmosis. Sharks are able to maintain this by ensuring that the amount of solutes in their internal environment is as much as that in their external environment.
Sharks retain a chemical contained in urine called UREA in their bloodstream to counter the osmotic effect of the salt concentration in the waters they live. This helps them maintain a concentration balance with their environment.
Answer:
The correct option is d. it causes exchange diffusion
Explanation:
Amphetamines are synthetic substances with a stimulating effect. Their action lies mainly in increasing synaptic levels of monoamines by various mechanisms, including diffusion exchange through membrane transporters. Amphetamine increases extracellular concentrations of serotonin by displacing the neurotransmitter from its specific presynaptic transporter. When amphetamine binds to serotonin transporters, on the one hand it prevents it from entering the terminal and on the other it reverses the recapture mechanism so that serotonin leaves the synaptic space.
The best answer in terms of how organ cultures are an improvement on this transport method is "<span>Cultured organs can be kept alive for several weeks before transplant."</span>
The series of events that take place in a cell<span> leading to its division and duplication (replication) that produces two daughter cells. </span>
