Of these listed which has is the least abundant in earths atmosphere a. argon b. ozone c. oxygen d. nitrogen

What function does a limb serve in each animal how are the limb bones of the four animal similar based on the similarities what can be inferred about the evolution of the poor animals

Genetic disorders can result when sister chromatids fail to seperate properly. during what phase is this problem most likely to occur?

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