Answer:
Cell surface receptors (membrane receptors, transmembrane receptors) are receptors that are embedded in the plasma membrane of cells. They act in cell signaling by receiving (binding to) extracellular molecules. They are specialized integral membrane proteins that allow communication between the cell and the extracellular space.
Explanation:
During the lifecycle of the plant we can encounter both haploid and diploid forms.
Haploid form of the plant is called a gametophyte. This form was created from spore and enables creation of haploid gametes in the next stage.
In addition to gravity, muscular peristaltic waves, originating in the renal pelvis, squeeze urine down the ureters and squirt it into the bladder, the peristaltic movements consist of radially symmetrical contractions and in the relaxation of the muscles that propagate in a wave downwards in the muscular tube, in an antegrade manner, such movements are also found in the esophagus and stomach.
