A control variable is: A. Measured to show the effect of a change. B. Collected to draw conclusions. C. Changed to test a hypothesis. D. Kept the same to make an experiment a fair test.

What did not occur in the proterozoic eon a)the oxygen levels increase greatly in the atmosphere,b)the emergence of the eukarya , c)muti cella’s eukaryotic organisms began to diversify,d)anaerobic bacteria kept thriving with more oxygen

Consider the venn diagram of plant reproduction. where in this image, areas a - d, would you insert the picture of the orange lily?

According to theories of how life began, how did early organic molecules begin to separate from the outside world? a: specialized enzymes were required b: chains of amino acids created a barrier c: formation of microspheres or vesicles d: rna catalyzed the formation of membranes