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WorksheetsBiological Membranes A-level OCR
Total questions: 20
Worksheet time: 19mins
Which one of the following is not a major component of the cell surface membrane?
glycolipid
glycoprotein
cholesterol
triglyceride
If two sucrose solutions of different concentrations are separated by a partially permeable membrane, which one of the following will occur?
The solute will diffuse from the more concentrated to the less concentrated solution.
Both solute and solvent will diffuse until equilibrium is reached.
The volume of the less concentrated solution will increase.
The volume of the less concentrated solution will decrease.
What is the approximate thickness of the plasma membrane?
0.75 nm
7.5 nm
75 nm
750 nm
The diagram shows a glass cylinder separated into two compartments, T and S, by a partially permeable membrane. The membrane is in the form of a sliding piston.
· the volume of T equals the volume of S (VT = VS).
· the concentration of sucrose solution in T is twice that in S (CT = 2CS).
Which one of the following will be true when osmotic equilibrium is reached?
CT = 2CS and VT = 2VS
CT = CS and VT = VS
CT = 2CS and VT = VS
CT = CS and VT = 2VS
Potassium cyanide interferes with the formation of ATP. The use of potassium cyanide reduces the rate at which molecules of a certain chemical enter the cell.
Select the process by which the molecules would normally enter the cell.
simple diffusion
facilitated diffusion
osmosis
active transport
If four solutions are made, each containing 10 g l -1 of one of the following molecules, which one would have the lowest water potential?
sucrose
glucose
DNA
haemoglobin
The vacuolar sap of a freshwater alga Nitella clavata and the pond water in which it was growing were analysed. The table shows the results.
Which one of the following processes accounts for these results?
active transport
facilitated diffusion
osmosis
simple diffusion
Which one of the following is not an acceptable description of the permeability of a cell surface membrane?
differentially
partially
selectively
semi
Which of these has the highest water potential?
5% sucrose solution
10% sucrose solution
20% sucrose solution
pure water
Which diagram shows the appearance of a plant cell with an original ψ of -1.2 MPa after being placed in a solution as shown?
A
B
C
D
Three plant cells, X, Y and Z, are in contact with each other. Their water potentials are shown in the table.
Which option correctly describes how water will move by osmosis between the cells?
X to Y X to Z Y to Z
Z to X Z to Y X to Y
X to Z Y to X Y to Z
Y to X Z to Y X to Z
What will happen if a red blood cell is placed in a solution with a more negative water potential?
becomes turgid
bursts due to osmosis
shrinks due to osmosis
stays the same
The water potential of a plant cell is -400 kPa. The cell is put in a solution with a water potential of -600 kPa. Which one of the following happens to the cell?
the cell bursts
the cell becomes turgid
the cell wall shrinks
the cell becomes plasmolysed
Several factors influence the rate of diffusion.
Which option correctly describes how these factors affect the rate of diffusion?
diffusion distance x size of particle
temperature x surface area x concentration difference
temperature x surface area x concentration difference
diffusion distance x size of particle
surface area x temperature x size of particle
diffusion distance x concentration difference
surface area x diffusion distance x temperature
concentration difference x size of particle
The graph shows the rate of diffusion of sodium ions into a cell at different external sodium ion concentrations.
What limits the rate of diffusion of sodium ions between A and B?
the number of channel proteins
the number of carrier proteins
the amount of ATP available
the concentration gradient of sodium ions
A sample of blood, added to a saline solution with a less negative water potential than the cell contents, results in a uniform red colour in the solution which is unaffected by centrifugation.
Which one of the following explains this result?
Haemoglobin has diffused through the erythrocyte membrane into the solution.
Water has entered erythrocytes by osmosis. As the cells are now less dense than the solution, they will not sediment on centrifugation.
Water has left the cells by osmosis, causing them to shrink and become too small to sediment on centrifugation.
Water has entered the erythrocytes by osmosis, causing them to swell and burst and the haemoglobin is released into the solution.
Carrot discs were placed in a solution containing K+ ions.
The concentration of O2 in the air bubbled through the solution was changed and the rate of K+ uptake measured. The results are shown.
Which process is responsible for the uptake of K+ in this experiment?
active transport
facilitated diffusion
osmosis
simple diffusion
In which sucrose concentration would the water potential (ψ) of the cells be the same as that of the external solution?
0.10 mol dm-3
0.25 mol dm-3
0.30 mol dm-3
0.40 mol dm-3
The initial length of the potato cylinder in the 0.1 mol dm-3 sucrose solution was 90 mm.
What was its final length?
75 mm
98 mm
108 mm
120 mm
Substance F enters by simple diffusion, substance G by facilitated diffusion.
Why does the curve for substance G level off above a certain concentration?
equilibrium is reached with the concentration of G being the same inside and outside of the cell
ATP becomes depleted
the membrane becomes impermeable to G above a certain concentration
carrier molecules are saturated
