Question

Compare osmosis, simple diffusion, facilitated diffusion and active transport: A) describe their differences and B) explain when cells have to use each one.

Answer 1

part A)

osmosis-it is movement of water from a region of lower concentration to higher concentration through a semipermeable membrane.this movement of water is along the concentration gradient.

simple diffusion- it is movement of ions or molecules from a region of high concentration to lower concentration.it is not necessary for semipermeable membrane and movement of ion or molecules is along the concentration gradient.

facilitated diffusion- it is a passive transport and movement of ion or molecules is across the concentration gradient and also it required semipermeable membrane.

active transport- it is movement of ion and molecules against concentration gradient. it required energy in form of ATP for its movement .

part B)

when cell required energy like ATP then it is using active transport,and when substance is water and passes through semipermeable membrane then it is using osmosis and when substance is other than water then it is using simple diffusion a and also its movement is down the concentration gradient without the use of a carrier protein and when it is using membrane protein for movement of substance then cell uses facilitated diffusion