<span>The formation of the fertilization envelope (slow-block to polyspermy) requires an increase in the availability of </span>calcium ions.
Slow-block to polyspermy is also called cortical reaction. In this reaction, the sperm will be permanently blocked by cortical granules. The release of calcium ion will trigger this reaction.
Answer: d. the wind
Wind is not a land resource. It is the natural movement of air across the earth surface. Wind is also considered as movement of gases present in the atmosphere. The strength and direction of wind can be measured. It is a atmospheric resource. Wind produces as a result of difference in the atmospheric pressure. When a difference in atmospheric pressure exist air moves from region of high pressure to low pressure area. Wind energy is renewable source of energy can be used to produce electrical energy.
