Question

Both simple diffusion and facilitated diffusion.
A. Transport molecules only along the concentration gradient and do not use energy.
B. Transport molecules only along the concentration gradient by the use of energy.
C. Transport molecules against the concentration gradient and do not use energy.
D. Transport molecules against the concentration gradient by the use of energy.

Answer 1

Hint: Diffusion is the movement of a substance from an area of high concentration to an area of low concentration.
Diffusion happens in liquids and gases because their particles move randomly from one place to another.
Diffusion is an important process for living things.
For example: You can smell perfume because it diffuses into the air and makes its way into your nose.
Cigarette smoke diffuses into the air.

Complete answer:
In order to solve this question we need to learn more diffusion and types of diffusion.
Diffusion: Diffusion is a process which refers to the movement of molecules from an area of high concentration to lower concentration
An example: The noxious smell of ammonia gas spreads in the air.
Active and passive transport are the two systems of transporting molecules across the cell membrane.
Active transport pumps molecules or the substance against a concentration gradient using energy.
For example: Sodium-potassium pump.
Passive diffusion also allows small, non-polar molecules or the substance to travel across the membrane which means along the concentration gradient without use of energy.
Three main type of passive diffusion are:
1. Simple diffusion: It is the process by which solutes are moved along a concentration gradient in a solution or without the consumption of energy.
2. Osmosis: It is a process by which molecules of a solvent tend to pass through a semipermeable membrane from a less concentrated solution into a more concentrated one.
3. Facilitated diffusion: It is the type of passive diffusion of solutes through transport proteins in the plasma membrane.
Facilitated diffusion is a type of passive transport.

So, the correct option is, option A - Transport molecules only along the concentration gradient and do not use energy.

Note:
Active transport is usually associated with accumulating high concentrations of molecules that the cell needs, such as ions, glucose and amino acids.
Examples of active transport include the uptake of glucose in the intestines in humans and the uptake of mineral ions into root hair cells of plants.
There are three main types of Active Transport:
The Sodium-Potassium pump,Exocytosis and Endocytosis.