Why does obsidian and igneous rock appear smooth and glassy

Study the diagram of a desert food chain . what would most likely happen if the kangaroo rats were killed off and removed from the food chain ?

An easy way to calculate the amount of energy available at each level is to what?

There are specialized producers that live in warm water vents deep in the ocean. these producers do not per-form from photosynthesis, but instead perform a similar process with iron and other chemicals. why do you think these producers use this process instead of photosynthesis?