Fossils in precambrian rocks are rare, while there are many fossils in rocks from the phanerozoic eon. what does this evidence suggest? a. there was a major change in the diversity of life in the phanerozoic eon, probably due to mass extinction. b. there was no life in the precambrian eon. c. the rocks from the phanerozoic eon are much harder than those from the precambrian eon. d. there was no change in the diversity of life in the phanerozoic eon.

Which of the following is one of the four conditions necessary for natural selection to occur in a population? fewer organisms are born than the habitat can support mutation does not occur organisms have identical characteristics variation is inherited

Asolution of an enzyme and a substrate was placed in a water bath and the temperature of the reaction was raised gradually. the graph shown was plotted at the end of the experiment. what can be concluded from the graph? a) temperature has no effect on the activity of the enzyme. b) the effect of temperature on the enzyme is unpredictable. c) the enzyme shows increased activity up to a certain temperature. d) the activity of the enzyme is inversely proportional to the temperature.

The vaccine in a flu shot contains weakened flu viruses. how does a flu shot work with the immune system? a. it destroys lymphocytes. b. it destroys macrophages. c. it activates macrophages. d. it activates lymphocytes.