Supplementary videos

How many carpels does a banana have? (a pea has one)
Blood groups and blood compatibility
Calico cat and X inactivation (random deactivation of an X chromosome)

Extra credit readings

• The Unfortunate Sex Life of the Banana Damn Interesting, 8/24/09
• Baby Mix-Up Times Online 10/10/07
• The Effect of Female Hormone Fluctuations on the Incidence of Trisomy in Humans FGCU 98
• A Sweet Remedy for Huntington's? New Scientist 1/21/04

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