OCR A-level Biology cells and membranes

Which one of the following is not a major component of the cell surface membrane?

• glycolipid

• glycoprotein

• cholesterol

• triglyceride

What is the approximate thickness of the plasma membrane?

• 0.75 nm

• 7.5 nm

• 75 nm

• 750 nm

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

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

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

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

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

Which of these is NOT a function of a ribosome

• Link amino acids together

• Match complementary nucleotides

• Translate the mRNA

• Make other ribosomes

Piece of equipment used to calibrate the graticule of a microscope

• Eyepiece

• Stage micrometer

• Fine focussing wheel

• Diaphragm

What is the cell wall of a prokaryotic cell made from?

• Peptidoglycan

• Cellulose

• Chitin

• Glucose