Name
section 4: diffusion and osmosis
study guide b
key concept
materials move across membranes because of concentration differences
vocabulary
passive transport
diffusion
concentration gradient
osmosis
isotonic
hypertonic
hypotonic
facilitated diffusion
main idea: diffusion and osmosis are types of passive transport.
1. what is a concentration gradient?
2. what does it mean for a molecule to diffuse down a concentration gradient?

Answer No 1:

A concentration gradient can be described as a phenomenon by which molecules travels from an area which is highly concentrated to an area which has low concentrations of that molecule.

Answer No 2:

A molecule is said to be diffusing down a concentration gradient when molecule acquire the phenomenon of concentration gradient i.e move from higher concentration to lower concentration. This mechanism is also termed as passive transport. Active transport is the opposite of passive transport. In active transport, molecules move against the concentration gradient i.e from an area of lower concentration to an area of higher concentration.

label a cell membrane

label b cytoplasm

label c ribosomes

label d dna

the membrane forms the outside of the cell

cytoplasm is the liquid within

ribosomes are the components within that distribute rna

the dna is the genetic make-up