A substrate cycle in a metabolic pathway . a. is a point that starts a cascade effect b. allows for substrates to be passed to alternative pathways c. is a good point for regulation of the pathway d. includes only diffusion-controlled reactions

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