Two objects, A and B, are 10 m apart. Objects C and D are 20 m apart. The gravitational attraction between objects C and D is greater than the attraction between objects A and B. Explain the reason for the difference in gravitational attraction.

Where would you expect to see seedless plants, such as ferns and mosses? a. in a botanical museum, because they are all extinct b. low and close to the ground in a moist environment c. climbing high while circling the branches of another plant d. deeply rooted in a forest with a trunk that reaches 20 meters or more

Which phrase is the best summary of the model shown? a. the transfer of the sun's energy through trophic levels b. a series of aerobic and anaerobic reactions c. a transformation of light energy into chemical energy d. the breakdown of food molecules

The “ecological footprint” left by a citizen of a developed nation is about four times larger than that left by a citizen of a developing nation. why is this the case?