Answer:
A dichotomous key is a tool created by scientists to help scientists and laypeople identify objects and organisms.
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Natural levels of nitrate in Minnesota groundwater are usually quite low (less than 1 milligram per liter [mg/L] of nitrate-nitrogen). However, where sources of nitrate such as fertilizers, animal wastes, or human sewage are concentrated near the ground surface, nitrate may seep down and contaminate the groundwater. Elevated nitrate levels in groundwater are often caused by run-off from barnyards or feedlots, excessive use of fertilizers, or septic systems.
Wells most vulnerable to nitrate contamination include shallow wells, dug wells with casing which is not watertight, and wells with damaged, leaking casing or fittings.
Nitrate contamination of a well is often regarded as a first sign of deteriorating groundwater quality.
A sedimentary rock can become an igneous rock by melting and solidification.
Answer:
mutation in DNA
Explanation:
Mutations are changes in the genetic code that can occur in many ways. Each time a cell divides, say, DNA must be copied into two copies, one copy for each new cell. Although this copying is very precise, it is still not perfect - for about every billion accurately copied databases, one is mistranslated.
Another source is DNA damage, which can occur spontaneously through the normal life of the cell, or through external toxins or negative influences (ultraviolet radiation, for example). Through evolution, cells have developed a very complex system for repairing changes in DNA, but these systems not only have limitations but can sometimes cause additional errors themselves.
Answer:
C. Sometimes molecules need to move from low to high concentrations.
Explanation:
