Biology by Bradford
2.7.A, 2.7.BCells in three solutions
1234
- 1
- 2
- 3
- 4
2.7 Tonicity and Osmoregulation: revision map
The subtopic in the middle and four tasks round it: label a diagram, complete a table and fill 10 gaps. Every box rests on a learning objective of the topic in the AP Biology course and exam description. Type into the blanks and check them, or print it on A4, Letter or A3 with an answer key.
Tonicity and Osmoregulation
AP Biology · Unit 2 Cell Structure and FunctionHover over a box to see it. Untick it to leave it off this sheet and its printout.
Name2.7.BRegulating water balance
A cell in fresh water takes in water by osmosis all the time. A protist such as Paramecium keeps from bursting with a , which collects excess water and pumps it out using ATP. Plant cells use their cell wall to stand the pressure of a hypotonic solution, and a central vacuole that stores water and solutes. Multicellular animals regulate the solute concentration of their body fluids, for example with kidneys, so that their cells stay close to isotonic.
Topic 2.7Tonicity and Osmoregulation
2.7.ATonicity and its effect
| Solution is | Water moves | Animal cell | Plant cell |
|---|---|---|---|
| into the cell | swells and may burst | becomes turgid; wall resists | |
| no net movement | no change | flaccid | |
| out of the cell | shrivels | plasmolyzed: membrane pulls from the wall |
2.7.AWater potential
Water moves by osmosis from a region of higher water potential to one of water potential. Water potential is the sum of the solute potential and the pressure potential: Ψ = Ψs + Ψp. Pure water at atmospheric pressure has a Ψ of , adding solute makes Ψs more negative, and a plant cell that is turgid has a positive Ψp that pushes back against further uptake. Solute potential is calculated as Ψs = −iCRT.
Word bank 0contractile vacuolecrenationHypertonicHypotonicIsotoniclowerlysisnormal cellwater entering
Answer key
Every box on the sheet with its gaps filled in, as the subtopic reads in full.
LabelCells in three solutions
- lysis
- normal cell
- crenation
- water entering
TableTonicity and its effect
Solution is Water moves Animal cell Plant cell Hypotonic into the cell swells and may burst becomes turgid; wall resists Isotonic no net movement no change flaccid Hypertonic out of the cell shrivels plasmolyzed: membrane pulls from the wall GapsWater potential
Water moves by osmosis from a region of higher water potential to one of lower water potential. Water potential is the sum of the solute potential and the pressure potential: Ψ = Ψs + Ψp. Pure water at atmospheric pressure has a Ψ of 0, adding solute makes Ψs more negative, and a plant cell that is turgid has a positive Ψp that pushes back against further uptake. Solute potential is calculated as Ψs = −iCRT.
GapsRegulating water balance
A cell in fresh water takes in water by osmosis all the time. A protist such as Paramecium keeps from bursting with a contractile vacuole, which collects excess water and pumps it out using ATP. Plant cells use their cell wall to stand the pressure of a hypotonic solution, and a central vacuole that stores water and solutes. Multicellular animals regulate the solute concentration of their body fluids, for example with kidneys, so that their cells stay close to isotonic.