Outside of the U.S., many cruise lines do not have automatic tipping policies, says McDaniel, as other countriesâ tipping customs are different than ours (and thus their staff is paid differently), so it may pay to look at cruises leaving from other countries and then look at their âsuggestedâ tipping options.
Best Answer: Active transport is the mediated process of moving particles across a biological membrane against a concentration gradient. If the process uses chemical energy, such as from adenosine triphosphate (ATP), it is termed primary active transport. Secondary active transport involves the use of an electrochemical gradient.
Active transport occurs in the following situations: it allows cells to take up nutrients or ions even when the concentration of substances outside the cell is very low. it allows cells to get rid of unwanted substances when their concentration is greater outside the cell. it enables the Na/K pump to work with ions moving in opposite directions.