Science · Facts & sources
4 sourced facts about biology and life on Earth, each with the context behind the number. 4 more are in today's round and appear here after it closes.
Answerabout 14%
That leaves an estimated 6.8 to 7.6 million species still undiscovered and undocumented.
Source: Species estimate research (via Wikipedia) (2011) en.wikipedia.org
Answerover 99%
Mass extinctions, including five major ones, have wiped out the vast majority of species across Earth's history.
Source: Species and extinction research (via Wikipedia) (2020) en.wikipedia.org
Answerabout 30 trillion
Remarkably, the body also hosts roughly 38 trillion bacteria, more bacterial cells than human cells.
Source: Human biology research (via Wikipedia), citing Sender et al. 2016 (2016) en.wikipedia.org
Answerabout 170 liters (150 quarts)
The kidneys reabsorb almost all the fluid they filter, releasing only a small fraction as urine.
Source: Human biology research (via Wikipedia) (2020) en.wikipedia.org