Northern lights or auroras can be seen within the sub-layer.
a. ozonosphere
b. ionosphere
c. exosphere
d. troposphere

Which of the following lines of evidence would best support your assertion that a particular plant is an angiosperm? a) it produces seeds. b) it retains its fertilized egg within its archaegonium. c) it lacks gametangia. d) it undergoes alternation of generations.

Why is the theory of evolution important? it disproves all other theories about how life began. it provides a topic for debate. it is a unifying concept in biology. it explains how life began. i know for sure, it is not "it is a unifying concept in biology."

What is the difference between a meteoroid and a meteor?