Cells in the interior of complex multicellular organisms are able to respond to environmental signals through: Question 1 options: receptors designed to directly detect changes in the external environment. diffusion of environmental cues through the outer layers of the body. signals sent from exterior cells that relay information about environmental changes. pH, temperature, or osmolarity receptors in the membranes of exterior cells. Save receptors designed to directly detect changes in the external environment. diffusion of environmental cues through the outer layers of the body. signals sent from exterior cells that relay information about environmental changes. pH, temperature, or osmolarity receptors in the membranes of exterior cells. Solution Answer: Cells in the interior of complex multicellular organisms are able to respond to environmental signals through: receptors designed to directly detect changes in the external environment. Cells of multicellular organisms have proteins (generally transmembrane) called receptors. These receptors binds to signaling molecule (any environmental signal i.e. temperature, osmolarity etc.) and initiate a physiological response for that particular signal. Different receptors are specific for different molecules and these are fall into three major classes.