(2) The substance that directly provides energy for all kinds of life is ATP. Its simple structure is A-P ~ P ~ P, and there are two high-energy phosphate bonds in the molecule. Only the high-energy phosphate bonds far away from A are easy to hydrolyze and provide energy. The process of ATP production by animal cells is produced through respiration.
(3) When blood sugar rises just after a meal, insulin secretion will increase, which will act on the liver and muscles and be converted into polysaccharides, thus maintaining the blood sugar concentration stable. The function of hormones depends on the recognition of receptor proteins on the cell membrane surface of corresponding receptor cells.
(4) When stimulated by cold, the secretion of thyroid hormone in the body increases, which promotes cell metabolism. In addition, the information obtained from the topic shows that this hormone promotes the development of the brain of young animals and can maintain the excitability of the nervous system of adult individuals, indicating that it is related to the development and function maintenance of the nervous system.
So the answer is: (1) organelle membrane and nuclear membrane (2) A-P ~ P ~ P, away from A, cells breathe.
(3) Insulin, liver, muscle and information exchange
(4) The development and function of thyroid hormone and nervous system.