For multicellularity to develop, there must be a mechanism of signaling among cells in the multicellular organism. which of the structures in the cell membrane receives signals from the environment or from other cells?

Receptors

Explanation:

The cell membrane has receptors integrated or embedded into to it known as Membrane receptors or trans-membrane receptors . Membrane receptors are specialized proteins  and act in cell signalling by receiving extracellular molecules by binding to them.

In multi-cellular organisms cell signalling allows speciation o groups of cells and when the signal is released the membrane receptors are the ones that will receive it.

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