What it means As the air's CO 2 content rises, sugar beets will likely increase rates of photosynthesis and use the additional carbohydrates produced to enhance overall size and weight of tap roots, which are 
(it; means; As the air's CO 2 content rises, sugar beets will likely increase rates of photosynthesis and use the additional carbohydrates) Context(it means,List([5, 13))):(the air's CO 2 content rises, sugar beets; will likely increase; rates of photosynthesis) (tap roots; are; ) (the air's CO 2 content rises, sugar beets; use; the additional carbohydrates produced) (the additional carbohydrates; produced; to enhance overall size and weight of tap roots)
it means,List([5, 13))
it the air's CO 2 content rises, sugar beets tap roots the air's CO 2 content rises, sugar beets the additional carbohydrates
means will likely increase are use produced
As the air's CO 2 content rises, sugar beets will likely increase rates of photosynthesis and use the additional carbohydrates
rates of photosynthesis
the additional carbohydrates produced
to enhance overall size and weight of tap roots