Question

Type of transport across the biomembrane without the help of proteins is
A. Facilitated diffusion
B. Active transport
C. Simple diffusion
D. Diffusion via symport

Answer 1

Hint: Active transport moves molecules and ions from a lower concentration to a higher concentration with the assistance of energy in the form of ATP. On the other hand, passive transport moves molecules and ions without any energy from a higher concentration to a lower concentration.

Complete Answer:
- Facilitated transport is a mode of transport that is passive. In comparison to simple diffusion, where materials migrate through a membrane without the assistance of proteins, materials disperse through the plasma membrane with the aid of membrane proteins in facilitated transport, also called facilitated diffusion.
- The term used to describe the processes of moving materials across the cell membrane involving the use of energy is active Transport. The sodium-potassium pump, exocytosis, and endocytosis are the three primary forms of active Transport.
- Simple diffusion can be described as the process through which solutes are transported through the semipermeable membrane along the concentration gradient (cell membrane). By easy diffusion, e.g. water, gases and urea are transported. This method of transport needs no energy for molecules to be transported across the cell membrane.
- A symporter is present in the plasma membrane and is responsible for transporting molecules across the cell membrane, this transport occurs at same time. It can be thought of as a cotransporter also.

So, the correct answer is 'Simple diffusion'.

Note: In case of symport, there are two different molecules which are moving in the same direction whereas in case of antiport, there is transport occurring in different directions. An uniport occurs when there is transport of one molecule that happens without the process of coupling along with the transport of any other molecule.