Which of the following insulate against the cold? carbohydrates lipids nucleic acids proteins

Lipids insulate against the cold. Fat is our natural coat produced by the over eating process. Not really sure, but it comes to mind that the layer under the skin can be the main reason for it as it prevents and keep our inner parts warm. Also the high blood flow that it demands can help by over circulating it.

The stages of fertilization can be divided into four processes:

1) sperm preparation,

2) sperm-egg recognition and binding,

3) sperm-egg fusion and

4) fusion of sperm and egg pronuclei and activation of the zygote.