Water on Earth’s surface seeps into rocks. When the water in the cracks freezes, it expands and breaks the rocks apart. This process is called frost wedging. Which spheres interact when this process occurs?

atmosphere, biosphere, cryosphere
hydrosphere, cryosphere, geosphere
biosphere, hydrosphere, cryosphere
cryosphere, atmosphere, geosphere

The concept of keystone species is controversial among ecologists because most organisms are highly interdependent. if each of the trophic levels is dependant on all others how can we say one is most important

Dna. we have heard that we are a product of our dna. but where is it? how do we "get" our dna? it is passed to us, from our parents, but in what form? several vocabulary words associated with inheritance are used interchangeably and sometimes, incorrectly. let's see if you can clear this up for someone just learning about inheritance and cell structure.

8) animals respond in various ways to stimuli detected through their senses. some of these responses are stimulated by the presence of danger. which of these animal responses is the best example of a response to an immediate threat? a) a rooster crows every morning at the first sign of light. b) as something approaches an octopus, it shoots a cloud of ink. c) from late fall until spring, bears hibernate to preserve energy. d) a dog is getting hot in the sunlight, so he moves to a shaded area.