Why nitrogen must cycle through an ecosystem

Which group of algae is characterized by unicellular organisms and includes some members that would be better classified as zooflagellates? euglenophytes red algae sporozoans green algae

Which of the following is an effect of the uneven heating of the earth by the sun? a sea breeze a land breeze a convection current all of the above

What environmental cues and landmarks do the geese use to determine the timing and direction of their migration over the mountains? how do they find their way?