Soil plant atmosphere continuum Soil plant atmosphere continuum The soil-plant-atmosphere continuum (SPAC) is the pathway for water moving from soil through plants to the atmosphere. Continuum in the description highlights the continuous nature of water connection through the pathway. The low water potential of the atmosphere, and relatively higher (i.e. less negative) water potential inside leaves, leads to a diffusion gradient across the stomatal pores of leaves, drawing water out of the leaves as vapour. As water vapour transpires out of the leaf, further water molecules evaporate off the surface of mesophyll cells to replace the lost molecules since water in the air inside
Photoreceptor cell across different cone types. The process of phototransduction occurs in the retina. The retina has many layers of various cell types. The best-known photoreceptor cells ("rods" and "cones") form the outermost layer. They are the photoreceptors responsible for sight. The middle layer contains bipolar cells, which collect neural signals from the rods and the cones and then transmit them to the innermost layer of the retina, where the neurons called retinal ganglion cells (RGCs), a small percentage of which are themselves photosensitive, organize the signals and send them to the brain. Activation of rods and cones is actually hyperpolarization; when