(1) According to the model diagram, mulberry leaves are chewed, silkworm excrement is eaten by fish, sugarcane is used by people, sugar residue is eaten by pigs, and pig manure can be used by fish, which embodies the principle of material recycling. In order to improve the self-regulation ability of fish pond ecosystem, the species of organisms and food chains are increased, which embodies the principle of species diversity. While obtaining agricultural and livestock products, it is necessary to put necessary materials and energy into this system, so that biology and environment are both coordinated and balanced, which embodies the principle of coordination and balance.

(2) Restriction endonuclease and DNA ligase are necessary tools for genetic engineering operation; Plant tissue culture technology can be used to culture sugarcane cells with target genes into plants; Whether the disease-resistant gene is integrated into the chromosome of sugarcane cells can be detected by hybridization between the genome containing the target gene as a probe and genomic DNA.

(3) In order to superovulate sows, gonadotropins should be injected into their bodies; The oocytes of thoroughbred pigs only have the ability to combine with sperm in the metaphase of meiosis, while the sperm of thoroughbred pigs need to be capacitated before in vitro fertilization. The physiological basis for the survival of recipient embryo transfer is that there is no immune rejection between recipient embryo and maternal uterus.

So the answer is:

(1) principle of material recycling, principle of species diversity, principle of coordination and balance, principle of integrity, etc.

(2) Restriction endonuclease and DNA ligase? Plant tissue culture DNA molecular hybridization

(3) Gonadotropin? M Ⅱ metaphase capacitated immune rejection