It is the repiratory and the circulatory
If a person skipped lunch is could cause a low blood sugar
level and this will likely affect the liver cells in having it to react in
which glycogenolysis occurs. This process in the liver cells is a way of
breaking down glycogen in a way to fuel the body as it turns into glucose.
Trophic levels go by,
Producer (The nuts)
Primary Consumer (Squirrels)
Secondary Consumer (Raccoons)
Tertiary Consumer (Bear)
So squirrels would be at a lower trophic level.
Hope his help :)