Barry is a vegan. his diet does not include foods that contain preformed vitamin a, and he does not take any vitamin a supplements.

Photosynthesis uses co2 and cellular respiration produces co2. we call the point when the two processes are in balance--when there is no net production of co2--the compensation point. how might you limit one of the processes in order to achieve a compensation point?

Which of the following best explains the changes in biodiversity shown in the graph?

Calcium is a substance found in vitamins that people take to strengthen their bones and teeth. which plant has been used for a similar purpose? ferns horsetails liverworts club mosses