AP Biology : Understanding Lipids

Study concepts, example questions & explanations for AP Biology

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Example Questions

Example Question #41 : Understanding Lipids

Which of the following is an example of a lipid?

Possible Answers:

triacylglycerol

chitin

amino acid

cellulose

Correct answer:

triacylglycerol

Explanation:

Triacylglycerol (also called a fat or triglyceride) is a type of lipid. Amino acids are the subunits that make up proteins. Chitin and cellulose are polysaccharides, or carbohydrates.

Example Question #141 : Biochemical Concepts

Which of the following terns best describes a molecule that contains three fatty acid chains bonded to a glycerol molecule?

Possible Answers:

Cellulose

DNA

Triglyceride

Glycogen

None of these

Correct answer:

Triglyceride

Explanation:

Structurally speaking, a triglyceride molecule contains three fatty acid chains covalently bonded to glycerol—specifically where the hydroxyl groups are located on the glycerol molecule.

Example Question #151 : Biochemical Concepts

A polyunsaturated lipid contains which of the following that is/are not contained in saturated lipids?

Possible Answers:

No double bonds

Multiple double bonds

A polar head group

Sulfur atoms in place of carbons

One double bond

Correct answer:

Multiple double bonds

Explanation:

The term saturated when describing a lipid means that a molecule has the maximum number of hydrogens on its carbons, it is saturated with hydrogens. An unsaturated lipid has less than the maximum amount of hydrogens bonded to its carbons because there is a double bond between two of the carbons. Lipids molecules can have one carbon to carbon double bond (mono-unsaturated) or multiple (poly-unsaturated).

Example Question #41 : Understanding Lipids

All of the following biomolecules form true polymers except __________.

Possible Answers:

glucose

nucleotides

sugars

fatty acids

amino acids

Correct answer:

fatty acids

Explanation:

Fatty acids occur as free molecules in trace amounts in living organisms. They usually occur as a component of several types of lipid molecules, and are not true monomers, even though 1-3 of them can be attached to a polar head group such as glycerol or a phosphate group. The rest of the choices listed form polymers. Amino acids form proteins, sugars such as glucose form carbohydrates, and nucleotides form both DNA and RNA.

Example Question #153 : Biochemical Concepts

Which of the following statements regarding lipid molecules is true?

Possible Answers:

They are soluble in water

They store genetic information

They must contain a phosphate group

They can be used as a source of energy

They are hydrophilic

Correct answer:

They can be used as a source of energy

Explanation:

Lipids can be used as an energy source and are often used by cells to store energy for future use. Phosphate groups are not found in all lipids. For example most steroids, which are lipids, do not have phosphate groups. Lipids are hydrophobic and are repelled by water.

Example Question #154 : Biochemical Concepts

Which of the following correctly describes saturated fats?

Possible Answers:

In saturated fats, the carbons contain the maximum amount of hydrogens bonded to them.

In saturated fats, the carbons have double bonds between them.

Saturated fats are usually liquid at room temperature.

Saturated fats have single bonds between nitrogen and carbon.

Correct answer:

In saturated fats, the carbons contain the maximum amount of hydrogens bonded to them.

Explanation:

In saturated fats, the carbons have single bonds between them and the maximum number of hydrogen atoms.  Saturated fats do not have nitrogen, and they are solid at room temperature.

Example Question #151 : Biochemical Concepts

Which of the following is true of unsaturated fats?

Possible Answers:

Unsaturated fats have the maximum number of hydrogens bonded to the carbons.

The nitrogens are bonded to a phosphate group in a chain.

Unsaturated fats have one or more double bonds between between carbons in the fatty acid chain.

Unsaturated fats are solids at room temperature.

Correct answer:

Unsaturated fats have one or more double bonds between between carbons in the fatty acid chain.

Explanation:

Unsaturated fats have at least one double bond between two carbons in the fatty acid and do not have the maximum number of hydrogens.  They do not contain nitrogen and are usually liquid at room temperature.

Example Question #151 : Biochemical Concepts

Which of the following is not a function of lipids?

Possible Answers:

Storing energy

Folding proteins

Maintaining body temperature

Signal transduction

Forming membranes around organelles

Correct answer:

Folding proteins

Explanation:

Lipids are what make up fats. Fats store energy and help insulate animals against the cold. They also form lipid bilayers that surround cells and organelles. All steroid hormones are derived from cholesterol, a lipid. Thus, lipids play a significant role in signal transduction. Folding proteins is a function left to other proteins.

Example Question #152 : Biochemical Concepts

Cholesterol is ultimately a type of steroid, meaning it is a part of what type of macromolecule?

Possible Answers:

Proteins

Sugars

Carbohydrates

Lipids

Nucleic acids

Correct answer:

Lipids

Explanation:

Cholesterol is a steroid and steroids are types of lipids. Cholesterol is common in animal cell membranes and works as a precursor for many other steroids and affects cell membrane fluidity.

Example Question #43 : Understanding Lipids

Which of the following is true regarding a saturated fatty acid?

Possible Answers:

It is a liquid at room temperature

It has at least one double bond in its hydrocarbon tail

It has no double bonds in its hydrocarbon tail

Its hydrocarbon tail is bent

Correct answer:

It has no double bonds in its hydrocarbon tail

Explanation:

A fatty acid is considered unsaturated if it contains one or more double bonds (indicated by the = sign). These double bonds occur between carbon atoms (represented as C). Be able to recognize the general structure of important macromolecules. Lipids rich in saturated fatty acids tend to be solids at room temperature (butter, lard, coconut oil).

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