Who are the producers in the gizmo? who are the consumers in the gizmo?

Grass is the producer in the Gizmo food chain as grass do not require to feed on any other organism for their nutrition

while the snake, hawk and rabbit are the consumer and they require to feed on the other organism to feed themselves. In this case rabbit feed on grass, snake feed on rabbit and hawk feed on snake

bradycardia ( blood presssure below 120/80mmhg )

it is contraindicated to give nitroglycerin to patients with blood pressure that is lower than normal range because the drug can cause blood pressure to drop further. it can lead to paradoxical bradycardia and less commonly, threatening hypotension.