What two conditions allow a substance to diffuse across a cell membrane?
A concentration gradient exists, and the membrane permits the substance to pass.
AQA GCSE Combined Science: Trilogy (8464) — Biology — Higher · 4.1.3.3
Revise AQA GCSE Combined Science: Trilogy (8464) — Biology — Higher specification point 4.1.3.3, Active transport, with free active-recall flashcards. Flip through the set or review every question and answer below.
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What two conditions allow a substance to diffuse across a cell membrane?
A concentration gradient exists, and the membrane permits the substance to pass.
What role does diffusion of gases and dissolved solutes play in organisms?
It helps organisms obtain substances they need and remove substances they produce.
In what direction does net diffusion occur across a cell membrane?
From higher to lower concentration, rather than in a direction determined by the cell.
What is osmosis?
The diffusion of water through a partially permeable membrane.
In which direction is the net movement of water by osmosis between solutions of different concentrations?
From the more dilute solution to the more concentrated solution.
Why can water move into or out of a cell by osmosis?
The cell membrane is partially permeable.
Where do root hair cells absorb mineral ions from?
The solution surrounding soil particles.
How can root hair cells absorb mineral ions when their concentration is lower in the soil solution than inside the cell?
By active transport against the concentration gradient.
Where does the energy for active transport of mineral ions into root hair cells come from?
Respiration.
Why do plants need the mineral ions absorbed by their roots?
For healthy growth.