Question

Select the correct option for the table given below.
$\begin{array}{ccc}& \text{Facilitated diffusion}& \text{Active transport}\\ \text{Transport saturates}& \text{yes}& \text{(1)}\\ \text{Uphill transport}& \text{(2)}& \text{yes}\end{array}$

• A. (1) is yes and (2) is no
• B. (1) is no and (2) is yes
• C. (1) is yes and (2) is yes
• D. (1) is no and (2) is no

Answer 1

The correct option is A (1) is yes and (2) is no

Facilitated diffusion and active transport are means of short distance transport in plants.
In facilitated diffusion, the substances move from a region of higher concentration to lower concentration and hence this type of transport is called downhill transport. The transport is aided with the help of membrane proteins.
In active transport, the substances move from a region of lower concentration to higher concentration and this type of transport is called uphill transport. This is done with the help of specialised proteins called pumps in the biological membranes that use energy to transport molecules against concentration gradients.
The number of membrane proteins (involved both in facilitated diffusion and active transport) is limited and hence they can be saturated if the concentration of molecules to be transported is high.