AQA GCSE Biology 9-1: 4.1.3 Transport
in Cells Exam Questions All Solved
Correct .
What is diffusion? - Answer Diffusion is the random net movement of particles from an area of higher
concentration to an area of lower concentration.
Examples of diffusion: - Answer - Oxygen and carbon dioxide in gas exchange.
- Urea from cells into the blood plasma for excretion in the kidney
How does concentration gradient affect rate of diffusion? - Answer A large difference in concentration
leads to a greater probability of molecular collisions over the region and therefore increases the rate of
diffusion.
How does temperature affect rate of diffusion? - Answer As temperature increases, the average kinetic
energy of particles increases. Greater kinetic energies lead to increased velocities. The increased velocity
means that there is a greater chance of collisions between particles, resulting in an increased rate of
diffusion.
How does surface area affect rate of diffusion? - Answer The larger the surface area of a membrane the
faster diffusion takes place because there's a larger exchange surface. I.e. there is a greater area on
which the diffusion can take place.
How does diffusion distance affect rate of diffusion? - Answer The shorter the distance between the
two points of diffusion the less time it needs for the molecule to arrive, and hence the greater the rate of
diffusion.
Why do single-celled organisms have a large surface area to volume ratio? - Answer This allows
sufficient transport of molecules into and out of the cell to meet the needs of the organism.
How are the small intestines adapted for exchanging materials? - Answer The small intestines are
adapted for the maximum absorption of digested food molecules because:
in Cells Exam Questions All Solved
Correct .
What is diffusion? - Answer Diffusion is the random net movement of particles from an area of higher
concentration to an area of lower concentration.
Examples of diffusion: - Answer - Oxygen and carbon dioxide in gas exchange.
- Urea from cells into the blood plasma for excretion in the kidney
How does concentration gradient affect rate of diffusion? - Answer A large difference in concentration
leads to a greater probability of molecular collisions over the region and therefore increases the rate of
diffusion.
How does temperature affect rate of diffusion? - Answer As temperature increases, the average kinetic
energy of particles increases. Greater kinetic energies lead to increased velocities. The increased velocity
means that there is a greater chance of collisions between particles, resulting in an increased rate of
diffusion.
How does surface area affect rate of diffusion? - Answer The larger the surface area of a membrane the
faster diffusion takes place because there's a larger exchange surface. I.e. there is a greater area on
which the diffusion can take place.
How does diffusion distance affect rate of diffusion? - Answer The shorter the distance between the
two points of diffusion the less time it needs for the molecule to arrive, and hence the greater the rate of
diffusion.
Why do single-celled organisms have a large surface area to volume ratio? - Answer This allows
sufficient transport of molecules into and out of the cell to meet the needs of the organism.
How are the small intestines adapted for exchanging materials? - Answer The small intestines are
adapted for the maximum absorption of digested food molecules because:
