Which of the following serve as antibodies? carbohydrates lipids proteins nucleic acids

Protein

Explanation:

Out of the four macromolecules, proteins are the ones that serve as antibodies.

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hormones in blood stream

image: dtc.ucsf.edu

endocrine glands secrete hormones into the blood stream near them; the hormones then travel in our bloodstream until it reaches its destination, called a target cell, in distance parts of the body. in the target tissue, hormones lock onto the target’s plasma membrane, called the receptor site.