Which of the following is an example of symbiosis?
a. barnacles living on a whale’s skin
b. a tree obtaining nutrients from the soil
c. phytoplankton absorbing the sun’s rays
d. a blue whale feeding on zooplankton

The energy needs of a human population are not affected by

Genetic disorders can result when sister chromatids fail to seperate properly. during what phase is this problem most likely to occur?

Which of these is an example of land degradation? a. containers designed to store pollutants leak. b. fertilizers provide too many nutrients to crops. c. garbage is buried so the land can be reclaimed later. d. a drought kills all the plants in an area, leaving bare land