Ascientist wants to determine which fertilizer is more effective—fertilizer x or fertilizer y. the best way for her to proceed would be to design an experiment with

a. two groups of plants—a group fertilized by y and a control group with no fertilizer.

b. two groups of plants—a group fertilized by x and a control group with no fertilizer.

c. three groups of plants—a group fertilized by x, a group fertilized by both x and y, and a control group with no fertilizer.

d. three groups of plants—a group fertilized by x, a group fertilized by y, and a control group with no fertilizer.

a

explanation:

4.) metal

"-the movement of carbon from the nonliving environment into living things and back to the environment

-carbon is the essential component of proteins, fats, and carbohydrates (which make up all organisms)

-carbon exists in air, water, and living organisms

-producers convert carbon dioxide in the atmosphere into carbohydrates during photosynthesis

-bacteria in the atmosphere cycles through the system in filtration units

-in cellular respiration, carbon is released back into the atmosphere as carbon dioxide

-some carbon is stored in limestone (forming one of the largest "carbon sinks" on earth)

-largest carbon reservoir on earth= limestone

-carbon stored in the bodies of organisms as fat, oils, or other molecules may be released into the soil or air when the organism dies

-this may form deposits of coal, oil, or natural gas (fossil fuels, which increased the atmospheric carbon dioxide)

-fossil fuels store carbon left over from bodies of organisms that died millions of years ago

-they are located in the surface of earth, deep within the earth and beneath the ocean floor."