The Database of Useful Biological Numbers - great stuff, although before using any hard-to-measure number, be sure to know how the measurement was done before you trust the result.
Check these out:
Number of hairs in human eyebrows: 600
Respiratory cost for slow growing gradd: 2.4 mmole ATP/g dry weight * day
ATP requirement for the creation of an E. coli cell: 12-20 billion ATP molecules.
Average diameter of a protein in E. coli: 5 nm
Fraction of total body energy that is used to drive sodium/potassium pumps in the human brain: 10%
Serotonin content in pineapple: 17ug/g
Total nasal epithelial cell surface area in a mouse: 300 mm^2
Lactose content in Reindeer milk: 2.5%
These numbers may not be good for anything, but do you really need to justify knowing the lactose content in Reindeer milk?
