Question

base your answers to questions 20 through 23 on the information below and on your knowledge of biology.
carbon cycle supports life on earth
life on earth is only possible with carbon. organisms on earth rely on carbon for the production of molecules used in life functions. various processes in the environment cycle carbon. in the ocean, the main producers in this cycle are plant - like microscopic organisms called phytoplankton.
20 which model below best identifies how phytoplankton cycle carbon between two of earth’s spheres?
(1) phytoplankton box with carbon dioxide and water input, glucose and oxygen output
(3) phytoplankton box with glucose and oxygen input, carbon dioxide and water output
(2) phytoplankton box with carbon dioxide and water input, glucose and oxygen input
(4) phytoplankton box with carbon dioxide and water output, glucose and oxygen output

Explanation:

Phytoplankton are producers that perform photosynthesis. Photosynthesis takes in carbon dioxide (from the atmosphere, part of the atmosphere sphere) and water (from the hydrosphere) and produces glucose and oxygen. So the model should show inputs of carbon dioxide and water into phytoplankton and outputs of glucose and oxygen. Model (1) has carbon dioxide and water as inputs and glucose (and oxygen, implied in photosynthesis) as output, matching photosynthesis which cycles carbon between the atmosphere (via CO₂) and biosphere (phytoplankton, then through the food web) or hydrosphere (water) and biosphere. Models (2) and (3) have glucose/oxygen as inputs (which is respiration, not what producers like phytoplankton do to cycle carbon initially), and model (4) has carbon dioxide and water as outputs which is incorrect. So model (1) is correct.

Answer:

(1)