| Date | November 2009 | Marks available | 2 | Reference code | 09N.3.SL.TZ0.11 |
| Level | Standard level | Paper | Paper 3 | Time zone | TZ0 |
| Command term | Outline | Question number | 11 | Adapted from | N/A |
Question
Outline two pieces of evidence that support the endosymbiotic theory for the origin of eukaryotes.
Markscheme
smaller/70S ribosomes in mitochondria/chloroplasts (as in prokaryotes);
circular DNA in mitochondria/chloroplasts (as in prokaryotes);
mitochondria/chloroplasts have double membrane;
similar size/shape of mitochondria/chloroplasts to prokaryotes;
Examiners report
Some very good answers, but, most often, candidates only explained the endosymbiotic theory, without outlining the pieces of evidence for it.
