Question 1

Which of the following statements best explains why sucrose does NOT give a positive result in Benedict’s or Tollen’s test?

Accepted Answer

Because both anomeric carbons in sucrose are involved in a glycosidic bond, leaving no free hemiacetal group.

Question 2

A carbohydrate has the molecular formula $$C_6H_{12}O_6$. It contains a carbonyl group at carbon 2 and forms a five-membered ring upon cyclization. Which sugar is this most likely to be?

Accepted Answer

Fructose

Question 3

How many possible stereoisomers exist for an aldohexose sugar?

Accepted Answer

$$2^4 = 16$

Question 4

Which of the following best describes the effect of cis double bonds in unsaturated fatty acids?

Accepted Answer

They introduce kinks in the chain, preventing tight packing and lowering the melting point.

Question 5

Which of the following statements about glycosidic bonds is TRUE?

Accepted Answer

Once a glycosidic bond forms at the anomeric carbon, that carbon can no longer mutarotate or act as a reducing sugar.

Question 6

Which of the following best explains why cartilage is 'springy' and acts as a shock absorber in joints?

Accepted Answer

Glycosaminoglycans in cartilage are highly negatively charged, causing electrostatic repulsion and attracting water.

Question 7

Which of the following is a correct description of the structure and function of waxes in nature?

Accepted Answer

Waxes are esters formed from a long-chain fatty acid and a long-chain alcohol, providing waterproofing.

Question 8

Which of the following best describes the difference between passive and active transport across cell membranes?

Accepted Answer

Passive transport moves molecules down their concentration gradient without energy input; active transport moves molecules against their gradient and requires energy.

Question 9

Which of the following statements about the ABO blood group antigens is CORRECT?

Accepted Answer

Type A blood has an extra N-acetylgalactosamine attached to the O-antigen foundation.

Question 10

Which of the following is a TRUE statement about the hydrolysis of triacylglycerols (TAGs) with a strong base?

Accepted Answer

It produces glycerol and fatty acid salts (soaps) in a process called saponification.

Question 11

Which of the following best describes the role of cholesterol in animal cell membranes?

Accepted Answer

Cholesterol modulates membrane fluidity, preventing it from becoming too rigid or too fluid.

Question 12

Which of the following is the correct sequence of events in the G-protein-coupled receptor (GPCR) mechanism for peptide hormone signaling?

Accepted Answer

Hormone binds receptor → G-protein releases GDP and binds GTP → G-protein activates adenylate cyclase → ATP is converted to cAMP.

Question 13

Which of the following is a distinguishing feature of steroid hormone action compared to peptide hormone action?

Accepted Answer

Steroid hormones diffuse through the cell membrane and bind to cytosolic or nuclear receptors to regulate gene expression.

Question 14

Which of the following best describes the structure of cellulose?

Accepted Answer

A linear polymer of β-D-glucose with β (1→4) linkages.

Question 15

Which of the following is the precursor for all eicosanoid signaling molecules?

Accepted Answer

Arachidonic acid

Question 16

Which of the following best explains why most trans fatty acids in the human diet are considered unhealthy?

Accepted Answer

Trans fatty acids are produced during partial hydrogenation and pack tightly, raising melting points and behaving like saturated fats.

Question 17

Which of the following best describes the difference between amylose and amylopectin?

Accepted Answer

Amylose is a linear polymer with α (1→4) linkages; amylopectin is branched with both α (1→4) and α (1→6) linkages.

Question 18

A patient is given a drug that acts as an antagonist at acetylcholine receptors. What is the most likely effect?

Accepted Answer

The drug will block acetylcholine from binding, reducing or preventing synaptic transmission.

Question 19

Which of the following best describes the process of mutarotation in sugars?

Accepted Answer

The equilibrium between α and β anomers of a sugar via the open-chain form in aqueous solution.

Chem 1120 Study Guide: Carbohydrates, Lipids, and Chemical Messengers

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