Final answer:
The fast block to polyspermy is a temporary mechanism that depolarizes the oocyte plasma membrane, while the slow block is a permanent mechanism called the cortical reaction. The cortical reaction involves the release of proteins and mucopolysaccharides to prevent further sperm binding and create a fertilization membrane.
Step-by-step explanation:
The fast block to polyspermy is a temporary mechanism that involves a near-instantaneous change in sodium ion permeability, which depolarizes the oocyte plasma membrane and prevents the fusion of additional sperm cells. This fast block lasts for about a minute. On the other hand, the slow block to polyspermy is a permanent mechanism called the cortical reaction. During the cortical reaction, cortical granules fuse with the oocyte plasma membrane and release zonal inhibiting proteins and mucopolysaccharides, which prevent further sperm binding and coat the nascent zygote in an impenetrable fertilization membrane.