Here are some past essay questions:
Here are some fantastic animated tutorials about Meiosis from McGraw Hill Education – how Meiosis works, the stages of Meiosis, Meiosis I, Meiosis II, Crossing-over, Independent Assortment & unique features of Meiosis.
From Sinauer Associates comes an animated, narrated tutorial on Independent Assortment which also includes a quiz; there’s also one on Independent Assortment & gamete diversity (with a quiz) and one on mistakes in meiosis – nondisjunction.
Mr. Andersen uses chromosome beads to simulate both Mitosis and Meiosis:
Independent Assortment & Segregation (click to enlarge)
Paul Andersen explains how Linked Genes behave using fruit flies in a 17m 22s tutorial.
The science of skin color – Angela Koine Flynn, a 5m vid from TED-Ed.
Breaking the illusion of skin color, a 15m TED-Ed video from Nina Jablonski
Crash Course Biology #15 – Speciation: Of Ligers & Men, in which Hank explains speciation in terms of finches, ligers, mules and dogs.
Paul Andersen (from Bozeman High) explains Reproductive Isolation and Speciation, then details the processes of Speciation & Extinction and finally describes Genetic Drift (this is more detail than is required for IB).
Here’s a presentation that explains the origin of species (speciation) very clearly: