The density wave theory suggests that the spiral arms of the milky way galaxy are the result of a wave moving around the galaxy.

Plants in the tundra biomes have had to adapt to live long periods of time without a. cool temperatures b. sunlight c. oxygen d. water

Which of the following insects is a decomposer? a. mosquito. b. caterpillar. c. beetle. d. none of the above.

Which of the following is not a consequence of urban sprawl? increased racial tensions the relocation of industry to the inner cities higher poverty rates in the inner cities higher unemployment rates in the inner cities population losses to inner cities