According to the fossil record, which of the following was the first organism on land? 1.amphibian 2. reptile
3. mammal
4. plant
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If scientists are wrong about earth's age based on radioactive material and the decay rates are really much faster, how would nuclear power plants be affected?

Overtime the pond slowly becomes more acidic due to the release of chemicals from a nearby factory. which of the organisms would most likely survive the change to their environment?

24. how are vaccines used to keep people healthy?