Choose the class of macromolecules that plays a role in cell structure, communication (hormones and neurotransmitters), membrane transport, catalysis (enzymes), recognition and protection (immune factors), and movement (contractile molecules). Multiple choice question.

it is a limiting nutrient limited by a single nutrient in the ecosystem, & the single goes very slow.

carbon traps heat so more of it makes it hotter causing global warming. during the ice age carbon levels in the atmosphere were low so it got very cold. so the common things between them is carbon levels in the atmosphere.

answerclassical conditioning;