Certain preparations contain killed or weakened live biological agents that, upon injection into our body, protect the body against those pathogens. what are these preparations called? a. vaccines b. enzymes c. t cells im on my very last plato test

Legumes, a type of plant, require rhizobia, a type of soil bacteria, to survive since these organisms fix nitrogen during photosynthesis. rhizobia use the legumes for food. what would most likely happen to the legume population if rhizobia suddenly became extinct?

How do you date a sample of rock that you suspect as being one of the earliest on earth

This comparative chart is an example of one that might be used by scientists and law enforcement personnel for identification purposes. the chart represents a technological advance called