AQA A LEVEL BIOLOGY - DIFFUSION Questions With Accurate
Answers
Definition of diffusion - Accurate answers the net movement of molecules or ions from a region
where they are more highly concentrated to one where their concentration is lower until evenly
distributed/until they reach equilibrium.
Diffusion - Accurate answers example of passive transport and does not use ATP; only uses kinetic
energy. Passive transport (no energy required) (does not require carrier proteins)
Passive Transport (Diffusion) - Accurate answers - all particles are constantly moving due to the
kinetic energy that they possess.
- the motion is random
- particles are bouncing off one another as well as other objects.
Molecules that can easily diffuse directly through the phospholipid bilayer - Accurate answers -
small
- non polar e.g. oxygen and carbon dioxide
- lipid soluble e.g steroids
Molecules that can NOT easily diffuse directly through the phospholipid bilayer - Accurate answers
- charged ions
- polar molecules
- large
- non soluble in lipids
Facilitated diffusion - Accurate answers a passive process which relies on kinetic energy of the
molecules that are diffusing.
Carrier proteins or channel proteins speed up the rate of diffusion for large molecules like ions and polar
molecules. No ATP is involved.
Answers
Definition of diffusion - Accurate answers the net movement of molecules or ions from a region
where they are more highly concentrated to one where their concentration is lower until evenly
distributed/until they reach equilibrium.
Diffusion - Accurate answers example of passive transport and does not use ATP; only uses kinetic
energy. Passive transport (no energy required) (does not require carrier proteins)
Passive Transport (Diffusion) - Accurate answers - all particles are constantly moving due to the
kinetic energy that they possess.
- the motion is random
- particles are bouncing off one another as well as other objects.
Molecules that can easily diffuse directly through the phospholipid bilayer - Accurate answers -
small
- non polar e.g. oxygen and carbon dioxide
- lipid soluble e.g steroids
Molecules that can NOT easily diffuse directly through the phospholipid bilayer - Accurate answers
- charged ions
- polar molecules
- large
- non soluble in lipids
Facilitated diffusion - Accurate answers a passive process which relies on kinetic energy of the
molecules that are diffusing.
Carrier proteins or channel proteins speed up the rate of diffusion for large molecules like ions and polar
molecules. No ATP is involved.
