Which of the following features of molecule or ion movement is an essential characteristic of simple diffusion? (choose all that apply) a. through a membrane b. using a transport protein c. the molecules moving are only water molecules d. uses added energy

Several bird species feed in a certain species of tree. each bird species feeds in a different part of the tree. which statement is true of these bird species? a. they have adapted to different niches due to competition b. they have a carnivorous relationship with the tree species. c. they have adapted to different niches due to predation d. they have a symbiotic relationship with the tree species.

Is there any solid scientific evidence that humans have been cloned?

18. over time, how do sand dunes tend to migrate? a. perpendicular to the movement of the wind b. in the same direction as the wind blows c. toward the wind d. in random directions