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Question 18N.2.SL.TZ0.5c

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Date November 2018 Marks available [Maximum mark: 7] Reference code 18N.2.SL.TZ0.5c
Level SL Paper 2 Time zone TZ0
Command term Discuss Question number c Adapted from N/A
c.
[Maximum mark: 7]
18N.2.SL.TZ0.5c
(c)

Discuss the cell theory and its limitations.

[7]

Markscheme

cell theory:

a. cell theory is the accepted explanation of life ✔

b. organisms are composed of «one or more» cells ✔

c. cells are the basic/fundamental/smallest units of life ✔

d. cells can only come from pre-existing cells ✔

e. spontaneous generation of life has been disproven ✔

limitations:

f. striated muscle cells contain many nuclei «while most eukaryotic cells have one nucleus»
OR
red blood cells have no nucleus «while most eukaryotic cells have one nucleus» ✔

g. giant algae have complex single cell structure
OR
organisms as large as giant algae would be expected to be multicellular, but they have only one cell with one nucleus ✔

h. aseptate fungal hyphae are tube-like structures that contain no cell membranes between the many nuclei
OR
slime molds contain many nuclei ✔

i. viruses have some characteristics of living organisms but are not cells ✔

j. if all cells come from pre-existing cells, where did the first one come from? ✔

 

Allow description of Pasteur’s experiments

Do not accept a list of limitations without explanation

Syllabus sections