Question
HLPaper 2
The electron micrographs show a typical prokaryote and a mitochondrion.
1.[4]
Compare and contrast the structure of a typical prokaryotic cell with that of a mitochondrion.
Verified
Solution
Differences:
- Prokaryote has a cell wall, but mitochondrion does not;
1 mark - Mitochondrion has a double membrane whereas prokaryote has a single membrane
OR
«Gram negative» bacteria have a cell wall between two membranes whereas mitochondrion has an intermembrane space between two membranes;1 mark - Mitochondrion has cristae/invaginations of inner membrane, but prokaryote does not
OR
Prokaryote «may have» flagella/pili/«slime» capsule, which mitochondria do not have;1 mark
2.[2]
Explain how mitochondria could have been formed from free living prokaryotes.
Verified
Solution
- Endocytosis/engulfing of prokaryote by a larger/another/anaerobic prokaryote/cell;
1 mark - Double membrane of the mitochondrion is the result of endocytosis
OR
Inner membrane of mitochondrion from engulfed cell and outer from food vacuole;1 mark - «Engulfed prokaryotic cell» was aerobic/respired aerobically/consumed oxygen
OR
«Engulfed prokaryotic cell» provided energy/ATP;1 mark - «Engulfed prokaryotic cell» not destroyed/not digested
OR
«Endo»symbiotic/mutualistic relationship developed;1 mark - «Engulfed prokaryotic cell» had its own DNA/own «70S» ribosomes;
1 mark
