Final Answer:
Phytoplankton can float because their cells contain this molecule.
Gas Vacuole
Step-by-step explanation:
Phyt:plankton can float because their cells contain gas vacuoles. These gas-filled structures provide buoyancy, allowing phytoplankton to remain suspended in the water column. Gas vacuoles function like flotation devices, enabling phytoplankton to position themselves optimally in the water column to access sunlight for photosynthesis.
The gas vacuole is typically a membrane-bound organelle filled with gas, often oxygen, which is produced during photosynthesis. This adaptation is crucial for phytoplankton, as it helps them regulate their vertical position in the water, maximizing their exposure to sunlight while minimizing the energy required for buoyancy.
In essence, the presence of gas vacuoles is a key adaptation that facilitates the ecological success of phytoplankton, allowing them to thrive in aquatic environments and contribute significantly to global primary production and nutrient cycling.