Question

Which among the following statements are incorrect?
I. Transport proteins are needed by both facilitated diffusion and active transport.
II. Porins are carrier proteins
III. The carrier proteins needed by facilitated and active transport are specific.
IV. There is no need for energy to pump molecules against a concentration gradient in active transport.
V. Transport rate reaches saturation point when all the transport proteins are used or engaged.

• A. IV and V
• B. I, II and III
• C. II and IV
• D. I,III and V

Answer 1

The correct option is C II and IV

The incorrect statements are II and IV.
Porins are channel proteins that form pores in the membrane and facilitate the transport of molecules across the membrane.
Energy is required for the transport of molecules from a region of lower concentration to higher concentration against a concentration gradient. This type of transport is called active transport.
The correct statements are I, III and V.
Facilitated diffusion and active transport require membrane proteins that cause the transport of molecules across the membrane. These proteins are very selective and only transport specific molecules.
The number of membrane proteins is limited and hence they can be saturated if the concentration of molecules to be transported is high.