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Date November 2017 Marks available 4 Reference code 17N.2.HL.TZ0.06
Level Higher level Paper Paper 2 Time zone TZ0 / no time zone
Command term Describe Question number 06 Adapted from N/A

Question

Cell biologists play an important role in research into disease, fertility, evolution and many other areas of science.

Describe the origin of eukaryotic cells according to the endosymbiotic theory.

[4]
a.

Cell biologists play an important role in research into disease, fertility, evolution and many
other areas of science.

Compare and contrast the processes of spermatogenesis and oogenesis.

[8]
b.

Cell biologists play an important role in research into disease, fertility, evolution and many
other areas of science.

Outline the evidence for evolution provided by selective breeding.

[3]
c.

Markscheme

a. mitochondria and chloroplasts are similar to prokaryotes

b. «host» cell took in another cell by endocytosis/by engulfing «in a vesicle»

    Allow “taking in” in place of “engulfing”

c. but did not digest the cell/kept the «ingested» cell alive

    OR

    symbiotic/mutualistic relationship «between engulfed and host cell»

d. chloroplasts and mitochondria were once independent/free-living «organisms»

e. DNA «loop» in chloroplast/mitochondrion

f. division/binary fission of chloroplast/mitochondrion

g. double membrane around chloroplast/mitochondrion

h. 70s ribosomes «in chloroplast/mitochondrion»

Award up to [2] for evidence from mpe to mph

[Max 4 Marks]

 

a.

a. both result in haploid cells/gametes

b. both involve mitosis at the start/in the «germinal» epithelium

c. both have cell growth «before meiosis»

d. both involve «two divisions of» meiosis

e. both involve differentiation to produce a gamete

f. both are stimulated by hormones

    OR

    spermatogenesis stimulated by testosterone and oogenesis stimulated by FSH

A table is not required but both statements in one row of the table must either be explicitly stated or clearly implied to award the mark

[Max 8 Marks]

b.

a. crop plants/domesticated animals/livestock produced by selective breeding

b. specific example of a domesticated animal/crop plant and the wild species from which it
was developed

   OR  

   specific example of a domesticated animal/crop plant and the features in it which have been improved «compared with the wild species»

   For example dogs have been developed from wolves

c. artificial selection/crossing selected varieties/eliminating undesirable varieties

d. «selective breeding/artificial selection can cause» significant/rapid change over time/from the original wild species

e. «changes due to selective breeding/artificial selection» shows natural selection can cause change/evolution «in a species»

[Max 3 Marks]

 

 

 

c.

Examiners report

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

Syllabus sections

Core » Topic 1: Cell biology » 1.5 The origin of cells
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