IB Biology HL 2.2.12 Endosymbiosis and Eukaryote Origins
Practise IB Biology HL 2.2.12 by evaluating endosymbiosis evidence for the origin of mitochondria and chloroplasts.
- Syllabus
- First assessment 2025
- Course
- IB Biology
- Level
- HL
Exam points
- Explain how engulfed prokaryotes could become mitochondria or chloroplasts through endosymbiosis.
- Use double membranes, circular DNA, 70S ribosomes, binary fission and size as evidence for endosymbiosis.
- Compare a mitochondrion with a prokaryote to evaluate similarities and differences supporting the theory.
A2.2.12 (HL)—Endosymbiosis origin of eukaryotes question 1
[Maximum number: 4]
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.
a. mitochondria and chloroplasts are similar to prokaryotes
b. «host» cell took in another cell by endocytosis/by engulfing «in a vesicle»
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»
Marking guidance:
Allow "taking in" in place of "engulfing"
Award up to [2] for evidence from mpe to mph
4 max
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