Question

katie wants to make ball - and - stick models of the four macromolecules. she has colored balls for each of the elements in these molecules, including the following.
red: hydrogen
black: carbon
purple: oxygen
green: nitrogen
in which macromolecule will she use the black, red, and purple balls in a ratio of 1:2:1?
carbohydrates
lipids
nucleic acids
proteins

Explanation:

Carbohydrates are composed of carbon (C), hydrogen (H), and oxygen (O) in a ratio of 1:2:1. For example, glucose (\(C_6H_{12}O_6\)) has 6 carbon atoms, 12 hydrogen atoms, and 6 oxygen atoms. The ratio of \(C:H:O = 6:12:6=1:2:1\). Lipids have a much lower oxygen - to - carbon ratio compared to carbohydrates. Nucleic acids contain nitrogen in addition to \(C\), \(H\), and \(O\). Proteins also contain nitrogen (in amino groups) along with \(C\), \(H\), and \(O\). Since the question asks for a macromolecule with \(C\), \(H\), \(O\) in a 1:2:1 ratio (black - carbon, red - hydrogen, purple - oxygen), and no nitrogen (green balls not in the required ratio), carbohydrates fit this description.

Answer:

carbohydrates