Other than adjusting the amount of light, what other variable might a scientist manipulate/change to increase the rate of photosynthesis by a plant?

Most of the carbon on earth is stored in the form of

Cathy hypothesized that corn would not grow in mud. to test this hypothesis, she took corn kernels and placed 5 in mud, 3 in soil, and 2 in water. to her surprise, the kernels in the mud grew faster than the kernels in the soil. what error might have caused these unexpected results? a. wrong hypothesis b. not enough variables c. undefined control d. too many variables

Along what geographical feature are most of the oil producing regions located