How can supplies of metals such as copper and aluminum remain healthy even though there is a dwindling amount in the earth's crust?

In what for do plants utilize nitrogen? why do they need nitrogen?

Researchers want to use edna to look for an invasive species in the water which of the steps would be likely do last

Ascientist is investigating the effects of salinity on fish development. he places fertilized fish eggs in an aquarium that contains low salinity and observes their development. what factor would improve experimental design the most? place the fish eggs in the open ocean because that is the natural habitat include another aquarium that has normal salinity to compare to the low salinity aquarium include an aquarium that replaces salt with sugar to confirm that the effects are specific to salt grow algae with the fish eggs in order to provide adequate nutrients to the developing embryos