A sample originally contained 1. 28 g of a radioisotope. It now contains 1. 12 g of its daughter isotope. How many half-lives have passed since the sample originally formed? 3 4 8 16.

What initially causes a nerve impulse? release of enzymes out of the neuron movement of chemicals into the dendrites of the neuron pathogens attacking the dendrites of the neuron red blood cells bathing the neuron

What should be the strand of complementary dna produced by the strand of dna shown below cgt ata

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