Question

(a couple of quick factoids, unrelated to the los you should focus on. this 6 - carbon molecule is hexane, which is a common component of gasoline. and from left to right, you are looking at what life scientists call a structural formula, a schematic or line diagram, and a space - filling model. again, these three all represent the same molecule.)
hydrocarbon tails can be straight, as shown above, for hexane, or bent. the bending occurs when one or more double bonds occur between carbon atoms in the chain, like so:

a hydrocarbon chain that has no double bonds is said to be saturated—meaning, full of single bonds—while a hydrocarbon chain that contains one or more double bonds is said to be unsaturated.
the distinction is important, because the strength of hydrophobic interactions depends on how closely the c and h atoms on different hydrocarbons chains pack together. saturated hydrocarbon chains pack together more tightly than unsaturated chains, so are held together more tightly by hydrophobic interactions.
lipids vary a great deal in fluidity. waxes, for example, are solid at room temperature while oils are liquid. predict which of the following attributes are typical of the hydrocarbon chains in waxes versus more - fluid lipids. select all that apply.
the hydrocarbon chains of waxes are saturated; those found in oils are not.
unlike oils, the hydrocarbon chains of waxes contain atoms other than c and h.
the hydrocarbon chains of waxes are polyunsaturated—meaning that they contain more than one double bond.
the hydrocarbon chains of waxes are longer than the chains found in oils.

Explanation:

• Saturated vs Unsaturated: Saturated hydrocarbon chains (like in waxes) have no double bonds and pack tightly due to stronger hydrophobic interactions, making waxes solid. Unsaturated chains (like in oils) have double bonds causing bends, looser packing, and fluidity.
• Atoms in Chains: Hydrocarbon chains by definition are made of only C and H. So the claim about waxes having other atoms is wrong.
• Polyunsaturated: Polyunsaturated means multiple double bonds (unsaturated). But waxes are saturated (no double bonds), so this is incorrect.
• Chain Length: Longer hydrocarbon chains (in waxes) increase van der Waals forces between chains, making them pack tighter and be solid. Shorter chains (in oils) have weaker forces, allowing more fluidity.

Answer:

• The hydrocarbon chains of waxes are saturated; those found in oils are not.
• The hydrocarbon chains of waxes are longer than the chains found in oils.