The dissolved oxygen concentrations were consistently higher in the lake with zooplankton and trout even though the lakes and the phosphorus levels were identical. Why could having consumers as well as producers in the lake change the amount of dissolved oxygen in the lake

Astudent wants to test the hypothesis that fertilizer improves the growth rate of grass seeds. to test this hypothesis, the student put the same amount of grass seed in 3 containers with the same type of soil. the student measured the growth at the end of the week. all plants received equal amounts of water and sunlight. if you were asked to graph this data, what would you place on the x-axis? a. fertilizer b. water c. plant growth d. week one