8. Which activity is an example of a chemical change? a)dissolving table salt in water
b)hammering aluminum into thin sheets
c)melting gold to make jewelry
d)burning wood to produce ashes

Why was the sample heated in step 5? describe the chemical principles involved in the reasoning behind this step?

Acell in the human nervous system whose primary function is to form myelin and the blood-brain barrier, respond to injury, remove debris, and enhance learning and memory is called a(n) cell.

Which of the following factors would not contribute to allopatric speciation? a) a population becomes geographically isolated from the parent population. b) the separated population is small, and genetic drift occurs. c) the isolated population is exposed to different selection pressures than the ancestral population. d) different mutations begin to distinguish the gene pools of the separated populations. e) gene flow between the two populations is extensive.