The picture below shows two organisms, a lily pad and a frog, that depend on each another by exchanging X and Y Which of the following is represented by X?
A. food
B. clean water
C. oxygen
D. carbon dioxide

What are the most explosive events that occur on the sun? umbras solar flares solar winds prominences

The table below shows the number of foot bones in some horse fossils.horse fossil recordhorse fossil number of foot bonesp 19q 17r 24s 13ancient horses had more bones in their foot then present-day horses. the present-day horse has 11 foot bones. what is the correct order of evolution of the horse starting from the youngest fossil? a. q p r s b. s r p q c. s q p r d. r p q s

Ecologist have observed a sharp increase of sulfur dioxide in the air . what might be a possible consequence of excessive sulfur dioxide in the air ? a. acid rain b. ozone layer depletion c.ozone layer hole d.increase in sea levels