Level L Biology
Basic Questions-answers
Chapter 7
1)
Diffusion, osmosis, active transport, facilitated diffusion, endocytosis, exocytosis.
2
a)
-thickness of the cell membrane, thin membrane meaning a short distance and so enable
more rapid rate of diffusion.
-size of particles being transported, small sized particles diffuse faster
-total surface area of the membrane where diffusion occurs, larger surface area allow a greater
number of particles to diffuse
-concentration gradient, larger diffusion gradient results in faster rate of diffusion.
-temperature, raising temperature increasing movement of particles and so result in faster rate
of diffusion.
-pressure, increased pressure increases the force with which particles move, so results in faster
rate of diffusion.
b)
3)
diffusion-high-low concentartion-equilibrium- concentration gradient.
true - false- false
false- true- false
4)
5
a)
Diffusion is the movement of molecules from a region of higher concentration to a
region of lower concentration.
b)
Its a special form of diffusion which takes place when substances move through special
pores in the cell membrane or with the assistance of special carriers called "protein
carriers".
c)
Its an energy consuming transport of molecules or ions across a membrane against a
concentration gradient using protein carriers.
d)
Endocytosis is taking in of food particles, into single celled animals eg. amoeba.
e)
exocytosis: expelling liquids or solids out of the cell via a temporary vacuole or vesicle
eg. gland cells producing enzymes.
a)
i)
osmosis is a special form of diffusion across a selectively permeable membrane,
whereby water molecules move from a place where they are in higher
concentration to a place where they are lower in concentration.
ii)
It is the net diffusion of water molecules from a region of high water potential to a
region of low water potential across a selectively permeable membrane.
b)
Water potential is a measure of whether a solution is likely to lose or gain water from
another solution.
Osmotic potential is a measure of the amount of dissolved material in solution.
c)
i)
A-B-C: LEFT TO RIGHT D- RIGHT TO LEFT
ii)
10% sugar solution.
iii)
10% salt solution.
iv)
distilled water
v)
osmosis.