Biology 9700 · AS & A Level · Fluid mosaic membranes

Fluid mosaic membranes — practice question

Paramecium is a single-celled protoctist with cilia. Their cilia are built in a similar way to those in the human trachea. The cilia beat to propel Paramecium through the water in which it lives. Fig. 6.1 shows Paramecium.
(a(i))[2]

Suggest the sequence of events that leads to the Paramecium moving backwards after it touches an object.

(a(ii))[2]

Suggest how Paramecium maintains a higher concentration of calcium ions in the surrounding water than inside the cell.

(b(i))[1]

Name the process by which water moves into Paramecium.

(b(ii))[1]

Suggest the link between the contractile vacuole’s rate of contraction and the water potential of the surrounding water.

(c)[2]

Describe how Paramecium DNA differs from the DNA of a prokaryotic cell.

Worked solution & mark scheme

This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: calcium ion channels open / membrane has greater permeability to $Ca^{2+}$

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