(N/A) $\Rightarrow$ Active transport uses energy to pump molecules against a concentration gradient.
$\Rightarrow$ Active transport is carried out by membrane proteins.
$\Rightarrow$ Hence,different proteins in the membrane play a major role in both active as well as passive transport.
$\Rightarrow$ Pumps are proteins that use energy $(ATP)$ to carry substances across the cell membrane.
$\Rightarrow$ These pumps can transport substances from a lower concentration to a higher concentration (uphill transport).
$\Rightarrow$ The transport rate reaches a maximum when all the protein transporters are being used or are saturated.
$\Rightarrow$ Like enzymes,the carrier protein is very specific in what it carries across the membrane.
$\Rightarrow$ These proteins are sensitive to inhibitors that react with protein side chains.