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Date November 2016 Marks available 3 Reference code 16N.2.HL.TZ0.2
Level Higher level Paper Paper 2 Time zone TZ0 / no time zone
Command term Deduce, Label, and State Question number 2 Adapted from N/A

Question

The image is an electron micrograph of the lining of the small intestine.

(i) Label the microvilli using the letter M and a nucleus using the letter N.

(ii) State the function of the goblet cell.

(iii) Deduce, with a reason, whether or not the goblet cell is likely to divide.

[3]
a.

Explain how the cell cycle is controlled.

[4]
b.

Markscheme

(i)

Award [1] for one microvillus labelled M and one nucleus labelled N.

Both are essential for the mark.

Do not award the mark if any structure is labelled incorrectly.

 

(ii)

secretion/exocytosis / produce mucous

Candidates are not required to have studied goblet cells, so are just expected to deduce from the vesicles that the function is secretion; allow enzyme secretion but reject answers suggesting secretion of something that is clearly incorrect such as secretion of bile.

 

(iii)

not likely to divide as specialized/differentiated
OR
not likely to divide (as nucleus) is in interphase/not in mitosis

Do not award a mark for stating that the goblet cell lacks a nucleus.

 

 

 

a.

a. cell cycle is a sequence of stages / cell cycle is G1, S, G2 and mitosis

b. (control of the cell cycle) by cyclins/cyclin

c. levels of cyclins rise (and fall)/fluctuate during the cell cycle/surge at different times/have to reach a certain concentration

d. conditions inside as well as outside the cell affect regulation

e. four cyclins/different cyclins to enter different stages of/events in the cell cycle / cyclins regulate the sequence/timing of the cell cycle / cyclins trigger the next stages

The idea of different cyclins acting at different phases must be clear.

f. cyclin-dependent kinases / cyclins bind to kinases and activate them

g. kinases phosphorylate other proteins

h. phosphorylated proteins perform specific functions in the cell cycle 

b.

Examiners report

[N/A]
a.
[N/A]
b.

Syllabus sections

Core » Topic 6: Human physiology » 6.1 Digestion and absorption
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