27. Producers fix carbon from through the process of a, carbon dioxide; decomposition b. carbon dioxide, cellular respiration G. carbon dioxide, photosynthesis d. oxygen, photosynthesis e oxygen, cellular respiration 29. Primary consumers eat: a. detritivores b. decomposers c. producers d. other consumers c. any organism that is at a different trophic level - 30. Secondary succession is likely to occur_ a. in a newly formed volcanic island b. in an abandoned field c. in a mature forest d. on land exposure by glacier retreat c, on land with little to no soil