IGCSE Biology Topic 3: Movement Into and Out of Cells MCQs – 30 Practice Questions with Answers (Cambridge 0610)
Free practice for Cambridge IGCSE Biology 0610 on movement into and out of cells, covering diffusion, osmosis and active transport, with every question followed by a worked explanation.
Diffusion
Q1. Which statement best defines diffusion?
- (A) Movement of water through a partially permeable membrane only, by osmosis
- (B) Net movement of particles down a concentration gradient
- (C) The movement of particles against a concentration gradient using energy
- (D) The bulk flow of liquid through a tube
Show Answer
Answer: B – Diffusion is the net movement of particles down a concentration gradient, from higher to lower concentration, as a result of their random movement.
Q2. Where does the energy for diffusion come from?
- (A) Kinetic energy from random movement of molecules and ions
- (B) Energy released by respiration in the mitochondria of the cell
- (C) Light energy trapped by chloroplasts
- (D) Heat from the surroundings only
Show Answer
Answer: A – The energy for diffusion comes from the kinetic energy of the random movement of molecules and ions.
Q3. Oxygen moves from the air in the lungs into the blood. Which process is mainly responsible?
- (A) Diffusion
- (B) Active transport
- (C) Osmosis
- (D) Egestion
Show Answer
Answer: A – Oxygen moves down its concentration gradient from the air into the blood by diffusion.
Q4. Which factor would speed up diffusion?
- (A) A smaller surface area for exchange across the membrane
- (B) A lower temperature
- (C) A longer distance to travel
- (D) A steeper concentration gradient
Show Answer
Answer: D – A steeper concentration gradient increases the rate of diffusion, while a smaller surface area, lower temperature or longer distance would slow it.
Q5. A drop of coloured dye spreads through still water without stirring. Which process explains this?
- (A) Active transport
- (B) Osmosis
- (C) Diffusion
- (D) Transpiration
Show Answer
Answer: C – The dye particles spread by diffusion, moving randomly from where they are concentrated to where they are less concentrated.
Q6. Which change would slow down the diffusion of a solute into a cell?
- (A) Increasing the temperature
- (B) Increasing the surface area of the cell membrane for exchange
- (C) Increasing the distance the particles must travel
- (D) Increasing the concentration difference
Show Answer
Answer: C – A longer distance to travel slows diffusion, while higher temperature, larger surface area and a steeper gradient speed it up.
Q7. Why does a thin exchange surface help diffusion in living organisms?
- (A) It increases the distance particles must travel before exchange
- (B) It stops diffusion altogether
- (C) It provides energy for active transport
- (D) It shortens the distance particles must travel
Show Answer
Answer: D – A shorter diffusion distance means particles reach their destination sooner, so thin surfaces speed up exchange.
Q8. Carbon dioxide diffuses out of respiring cells into the blood. In which direction is its concentration gradient?
- (A) From higher concentration in the cells to lower concentration in the blood
- (B) From lower concentration in the cells to higher concentration in the blood
- (C) Against the gradient, using energy
- (D) There is no gradient for carbon dioxide
Show Answer
Answer: A – Respiring cells produce carbon dioxide, so its concentration is higher in the cells than in the blood, and it diffuses down that gradient.
Q9. Some substances move into and out of cells by diffusion through the cell membrane. Which property of the membrane makes this possible?
- (A) It is fully impermeable
- (B) It pumps every substance against its gradient using energy
- (C) It allows some substances to pass through by diffusion
- (D) It breaks down all solutes
Show Answer
Answer: C – Some substances move into and out of cells by diffusion through the cell membrane.
Q10. Which of the following is an example of the importance of diffusion of gases in a living organism?
- (A) Water entering a root hair cell by osmosis from the soil
- (B) Oxygen reaching cells and carbon dioxide leaving them
- (C) Mineral ions being pumped into a root hair
- (D) Glucose being stored as starch
Show Answer
Answer: B – Diffusion of gases matters because oxygen must reach respiring cells and carbon dioxide must leave them.
Osmosis
Q11. Which statement best defines osmosis?
- (A) Net movement of any solute from low to high concentration, using energy from respiration
- (B) The movement of water using energy from respiration
- (C) Movement of water through a fully permeable membrane only, in either direction
- (D) Water moving down a water potential gradient through a partially permeable membrane
Show Answer
Answer: D – Osmosis is the net movement of water molecules down a water potential gradient through a partially permeable membrane.
Q12. Water is described as a solvent in organisms. Why is this role important?
- (A) It prevents any substances from dissolving in the cytoplasm
- (B) It makes water move only by active transport, never by osmosis
- (C) It stops diffusion in cells
- (D) It allows substances to dissolve so they can be transported
Show Answer
Answer: D – Water acts as a solvent with reference to digestion, excretion and transport, because dissolved substances can move and react more readily.
Q13. A plant cell is placed in pure water. In which direction will water move by osmosis?
- (A) Out of the cell only
- (B) Into the cell, as the cell sap is more concentrated
- (C) Equally in both directions, with no net movement of water at all
- (D) By active transport out of the cell
Show Answer
Answer: B – Pure water has a higher water potential than the more concentrated cell sap, so water moves into the cell by osmosis.
Q14. A piece of plant tissue gains mass after being placed in a dilute solution. What does this gain in mass show?
- (A) Net loss of water by osmosis
- (B) Active transport of water out of the tissue
- (C) No movement of water at all
- (D) Net uptake of water by osmosis
Show Answer
Answer: D – A gain in mass shows that water has entered the tissue by osmosis faster than it has left.
Q15. Dialysis tubing is used to investigate osmosis in the laboratory. Why is it a useful model of a cell membrane?
- (A) It is partially permeable, like a cell membrane
- (B) It is fully permeable to all substances, including large solutes
- (C) It carries out active transport
- (D) It contains living cells
Show Answer
Answer: A – Dialysis tubing acts as a partially permeable membrane, modelling how water moves into and out of cells by osmosis.
Turgor, plasmolysis and active transport
Q16. A plant cell placed in pure water becomes turgid. What does turgid mean here?
- (A) The cell has lost water and its cytoplasm has shrunk away from its wall
- (B) The cell has burst
- (C) The cell is full of water, pressing on its wall
- (D) The cell has stopped photosynthesising
Show Answer
Answer: C – A turgid plant cell is full of water, and the pressure of its contents pressing outwards on the cell wall is turgor pressure.
Q17. Plants are supported by the pressure of water inside their cells pressing outwards on the cell wall. What is this pressure called?
- (A) Osmotic pressure in the soil
- (B) Atmospheric pressure
- (C) Diffusion pressure
- (D) Turgor pressure
Show Answer
Answer: D – Turgor pressure is the outward push of the cell contents against the cell wall in a water-filled plant cell.
Q18. A plant cell placed in a concentrated sugar solution loses water. What happens to the cell?
- (A) It becomes turgid as water presses outwards on the cell wall
- (B) Its cytoplasm shrinks away from the cell wall (plasmolysis)
- (C) It gains mass rapidly
- (D) Its cell wall dissolves
Show Answer
Answer: B – In a concentrated solution water leaves the cell by osmosis, the cytoplasm shrinks and pulls away from the wall, which is plasmolysis.
Q19. A wilted plant has flaccid cells. What does flaccid mean in this context?
- (A) The cells are full of water and press firmly against their walls
- (B) The cells have burst
- (C) The cells have lost water and lost their firmness
- (D) The cells have divided
Show Answer
Answer: C – Flaccid cells have lost water and turgor, so they no longer press outwards firmly on the cell wall and the plant wilts.
Q20. Why is water potential important in the uptake of water by a plant root?
- (A) Because water potential stops osmosis
- (B) Because roots pump water upwards using light energy from sunlight
- (C) Because water potential only matters in leaves
- (D) Water moves by osmosis from soil to root cells down a gradient
Show Answer
Answer: D – Water moves by osmosis down a water potential gradient, so the difference in water potential between soil and root cells drives uptake.
Q21. Active transport is best defined as which of the following?
- (A) Movement of particles down a concentration gradient without using energy
- (B) Particles moving against a gradient, using energy from respiration
- (C) Movement of water through a partially permeable membrane
- (D) Random movement of particles in a liquid
Show Answer
Answer: B – Active transport moves particles against their concentration gradient, from lower to higher concentration, using energy from respiration.
Q22. Root hairs take up mineral ions from soil water even when the ions are more concentrated inside the root hair than outside. Which process allows this?
- (A) Active transport against the gradient
- (B) Diffusion down a concentration gradient
- (C) Osmosis of water molecules
- (D) Plasmolysis of the cell
Show Answer
Answer: A – Moving ions against their concentration gradient requires energy, so root hair ion uptake uses active transport.
Q23. During active transport, what moves molecules or ions across the membrane?
- (A) Chloroplasts, which trap light energy
- (B) Vacuoles
- (C) Protein carriers
- (D) Cell walls
Show Answer
Answer: C – Protein carriers move molecules or ions across a membrane during active transport.
Q24. A cell needs to absorb glucose from a solution where glucose is already more concentrated inside the cell than outside. Which process must it use, and why?
- (A) Active transport, needing energy to move against the gradient
- (B) Diffusion, because glucose molecules move randomly in solution
- (C) Osmosis, because glucose is dissolved in the surrounding water here
- (D) Plasmolysis, because the cell will shrink
Show Answer
Answer: A – Movement against a concentration gradient cannot happen by diffusion, so the cell must use active transport powered by energy from respiration.
Q25. A student compares two plant tissues, one in a dilute solution and one in a concentrated solution. Which pair of outcomes is expected?
- (A) One gains water and becomes turgid; the other loses water
- (B) Both become turgid
- (C) Both become plasmolysed as their cytoplasm shrinks from the wall
- (D) Neither changes in mass because water cannot cross the membrane
Show Answer
Answer: A – Water moves by osmosis towards the more concentrated solution, so tissue in dilute solution gains water while tissue in concentrated solution loses it.
Q26. Which statement correctly distinguishes diffusion, osmosis and active transport?
- (A) Diffusion and osmosis need energy from respiration, while active transport needs none
- (B) Diffusion is down-gradient, osmosis is water movement, active transport is against-gradient
- (C) Osmosis moves dissolved solutes, diffusion moves only water molecules, and active transport moves only gases
- (D) All three move particles against a concentration gradient
Show Answer
Answer: B – Diffusion is down-gradient movement, osmosis is water movement through a partially permeable membrane down a water potential gradient, and active transport is against-gradient movement using energy.
Q27. An animal cell placed in pure water would be expected to do what, unlike a plant cell?
- (A) Swell and burst, having no rigid cell wall
- (B) Become turgid and stay intact because of its rigid cell wall
- (C) Shrink by plasmolysis
- (D) Stop all diffusion
Show Answer
Answer: A – Water enters by osmosis, and without a cell wall an animal cell cannot resist the swelling as a plant cell does through turgor pressure.
Q28. Why does raising the temperature usually increase the rate of diffusion?
- (A) It makes the membrane fully impermeable to all substances
- (B) It reverses the concentration gradient
- (C) It raises the kinetic energy of particles
- (D) It provides energy for active transport only
Show Answer
Answer: C – Higher temperature raises the kinetic energy of molecules and ions, so their random movement and net diffusion speed up.
Q29. A root hair cell absorbs both water and mineral ions. Which process accounts for each?
- (A) Water by active transport and mineral ions by osmosis instead
- (B) Both by diffusion only
- (C) Water by osmosis and mineral ions by active transport
- (D) Both by active transport only
Show Answer
Answer: C – Water enters root hairs by osmosis down a water potential gradient, while mineral ions are taken up by active transport against their gradient.
Q30. In an osmosis experiment, a potato strip in a concentrated solution loses mass. What is the best explanation?
- (A) The potato has carried out active transport of water inwards
- (B) Water moved out of the cells by osmosis into the solution
- (C) Diffusion of sugar into the cells has reduced their mass
- (D) The potato cells have become turgid
Show Answer
Answer: B – Water moves by osmosis from higher water potential inside the cells to lower water potential in the concentrated solution, so the strip loses mass.
Go back over any process you confused with another, practise stating each definition in one sentence, and then retake the set until diffusion, osmosis and active transport are easy to tell apart.