Changing the levels of sugar in each mouse's diet would be the independent variable, and the c hange in weight would be the dependent variable, because the change in weight DEPENDS on the amount of sugar they receive.
Answer: The trophic levels of a food chain are the number of steps from the beginning of the chain.
Explanation:
A food web/chain starts with trophic level 1 (primary producers), trophic level 2 (herbivores), trophic level 3 (carnivores) and so on.