Explain why an area with extreme temperatures like the artic, would be resistant to invasion by a biotic disturbance?

1) what three conditions must be present for minerals to form through natural processes? 2) why are minerals considered inorganic substances? 3) how do oxides differ from other minerals that contain oxygen atoms? 4) how is a sulfide different from a sulfate? what makes native elements unique?

Which of these is not a nucleotide base found in dna?

Crossing over is a method of (blank)?