| Date | November 2009 | Marks available | 2 | Reference code | 09N.3.SL.TZ0.12 |
| Level | Standard level | Paper | Paper 3 | Time zone | TZ0 |
| Command term | Compare | Question number | 12 | Adapted from | N/A |
Question
Compare sympatric speciation and allopatric speciation.
[2]
a.
Discuss the concept of punctuated equilibrium.
[3]
c.
Markscheme
both involve reproductive isolation / separation of gene pools;
sympatric is speciation due to isolation of populations living in the same geographic area whereas allopatric is speciation due to geographic isolation;
a.
long periods of stability;
environmental change / sudden change;
leads to rapid speciation/evolution;
helps to explain absence of intermediate forms;
competing theory is gradualism;
c.
Examiners report
As in most compare questions, candidates failed to make comparisons and just described each type of speciation.
a.
Although there were some weak answers, many candidates answered this question correctly.
c.
