Renewable resources a. can be replenished over months, years, or decades b. are all living resources c. have finite supplies that will one day be used up d. include iron, natural gas, and copper

These factors threaten north americas ecosystems

One disadvantage that darwin faces today is w. enemy attacks x. natural disasters y. lack of land bridge z. high population density

Tides are caused by a differences in the gravitational force of the sun at different points on earth. differences in the gravitational force of the moon at different points on earth differences in earth’s gravitational field strength at different points on earth’s surfac fluctuations in the gravitational attraction between earth and the moon.