It's biology
please help!!​

Which of the following is a reason why early living organisms on earth could not have survived on the surface? 1. the lack of an ozone layer 2. the lack of oxygen in the atmosphere 3. the fact that these organisms were single-celled

Climate like that in the sahara desert have the fastest rates of weathering

What tool do geneticists use to predict the outcome of genetic crosses? a.karyotype b.punnett square c.centrifuge