Relationship between pesticide patents at home and abroad

(1) The principle of food chain writing is: the food chain only includes producers and consumers, excluding decomposers and abiotic parts; The food chain starts from the producer and ends at the highest trophic level; Arrows in the food chain point from prey to predators. The flow of matter and energy in the ecosystem will gradually decrease along the food chain and food web. According to the energy diagram of four kinds of organisms in the ecosystem, the food chain relationship between them is: B → A → C → D. 。

(2) The energy in the ecosystem is fixed by the producers through photosynthesis.

(3) Bioaccumulation refers to the accumulation process of some harmful substances (such as heavy metals and chemical pesticides) in the environment. ) accumulate in organisms through the food chain. Because of their stable chemical properties, these harmful substances are difficult to decompose and excrete in organisms, so they accumulate with the increase of trophic level, which is the most harmful to consumers at the top of this food chain. According to (1), D is the top consumer.

(4) The food chain includes producers and consumers in the ecosystem, and unmarked biological components are decomposers.

So the answer is: (1) b → a → c → d; (2)B fixed solar energy; (3)D； (4) decomposers.