Question

Facilitated diffusion
A) Doesn’t involve permease and doesn’t require energy .
B) Involves permease but does not require energy
C) Requires energy but does not involve permease
D) Moves substance from a region of higher concentration to a region of lower concentration

Answer 1

Hint: Transportation in plants are carried out by the vascular bundle- xylem and phloem. Transportation in plants can be done either through active transportation or by passive transportation i.e with or without using energy. Facilitated diffusion is a type of passive transportation.

Complete answer:
Diffusion is the process of movement of molecules from high concentration to low concentration. The diffusion of any substance depends upon the solubility in the membrane. The lipid-soluble substance rapidly diffuses through the membrane while water-soluble substance show difficulty in diffusion and so some special type of membrane protein called the permease helps in the transfer of these molecules.

In facilitated diffusion, specific proteins called channel proteins are enhancing the facilitated diffusion like porins. Porins are 16 -stranded beta-barrel proteins that create pores in the membrane of mitochondria, plastids, bacteria, 8 types of porins are present in gram-negative bacteria called Aquaporins.

Facilitated diffusion depends upon the living system. It does not require any energy for its transportation. The transport of substance occur in three ways –
Symport – in this two molecules cross the membrane in the same direction.
Antiport- in this two molecules cross the membrane in opposite direction.
Uniport- a molecule cross in only one direction or moves freely across the membrane.
So from the above discussion, we can easily make out that facilitated diffusion doesn’t require energy but requires permease.

Thus the correct answer is option ‘B’.

Note:
- Facilitated transportation involves two types of proteins – channel proteins and carrier or membrane protein.
- Facilitated diffusion doesn’t require energy because it does downhill transportation i.e. from higher concentration to lower concentration.