In mass flow,various substances move independently according to their

$A-$ In an antiport,both molecules move in opposite directions.
$R -$ In symport,only one molecule crosses the membrane in the same direction.

Why is active transport considered important?

Active transport is affected by

Which of the following transport induces conformational changes in proteins?

Read carefully the given table and choose the option that correctly fills the blanks in it.

Property	Simple Diffusion	Facilitated Transport	Active Transport
Requires special membrane proteins	No	$a$	Yes
Transport saturates	No	Yes	$b$
Uphill transport	$c$	No	Yes
Requires $ATP$ energy	No	No	$d$

Identify the values for $a, b, c, d$.