2. the cell membrane, diffusion, osmosis.

Question 1

cell membrane

Answer 1

the cell membrane is selectively permeable.

Question 2

what is the cell membrane composed of

Answer 2

1. it is a bilayer of phospholipid molecules (fluid)
2. Protein molecules scattered throughout (mosiac)
   membrane has a “fluid-mosiac model”

The phosphate head is hydrophilic (water loving) and the lipid tails are hydrophobic (water hating)

All cells need fuel (food), oxygen, amino acids etc and also need to get rid of waste E.g carbon dioxide.

Question 3

define diffusion

Answer 3

diffusion is the movement of a substance/molecule from an area of high concentration to an area of low concentration down a concentration gradient.
Diffusion is a passive transport mechanism, does not require energy (ATP) e.g oxygen, co2, glucose.

Question 4

define osmosis

Answer 4

the movement of water molecules from an area of high water concentration to an area of low water concentration down an concentration gradient.
>also passive, does not require energy (ATP).

Question 5

effect of osmosis in red blood cells (animals)
define a hypotonic solution

Answer 5

a hypotonic solution has a higher concentration of water than the water concentration in the red blood cells.
cells will gain water by osmosis and burst.

Question 6

define an isotonic solution

Answer 6

an isotonic solution has the same or equal concentration as the cell.

Question 7

define an hypertonic solution

Answer 7

an hypertonic solution has a lower water concentration then the cell. The water will move from a higher water concentration to an lower water concentration outside the cell and the cell will shrivel.

Question 8

osmosis in a plant cell (isotonic, hypotonic, hypertonic)

Answer 8

isotonic - stays the same

hypotonic - cell wall prevents bursting of cell wall. Plant would be “turgid”

hypertonic - plant cell is plasmolyzed. Plant would be flaccid