"up-regulation involves the loss of receptors and prevents the target cells from overreacting to persistently high hormone level"a. trueb. false

The above statement is false.

Explanation:

During up-regulation a cell tends to increase its number of receptors. During down regulation, loss of receptors takes place.

During up regulation the cell tends to become more sensitive to a particular hormone. Up-regulation occurs when the concentration of a hormone is very little. This method is useful because when the concentration of a hormone are less, increasing the hormone receptors increases the chances of the cell to interact with the hormone.

false because ozone (o3) depletion does not cause global warming, but both of these environmental problems have a common cause: human activities that release pollutants into the atmosphere altering it.

global warming is caused primarily by putting too much carbon dioxide into the atmosphere when coal, oil, and natural gas are burned to generate electricity or to run our cars.

explanation: