Question 1

Which of the following statements best explains why most natural unsaturated fatty acids are liquids at room temperature?

Accepted Answer

They contain cis double bonds, which introduce kinks and prevent tight packing.

Question 2

A sugar solution rotates plane-polarized light to the right. Which property of the sugar is responsible for this behavior, and how is it measured?

Accepted Answer

The presence of chiral centers; measured by a polarimeter.

Question 3

Which of the following best describes the difference between D- and L-glucose?

Accepted Answer

D-glucose has the -OH group on the right at the chiral carbon furthest from the carbonyl; L-glucose has it on the left.

Question 4

How many possible stereoisomers exist for an aldohexose sugar?

Accepted Answer

$$2^5 = 32$

Question 5

Which of the following disaccharides is non-reducing and does NOT undergo mutarotation?

Accepted Answer

Sucrose

Question 6

Which of the following statements about the hydrolysis of glycosidic bonds is correct?

Accepted Answer

It requires an acid catalyst to proceed efficiently.

Question 7

A patient is diagnosed with a deficiency in the enzyme that hydrolyzes acetylcholine in the synaptic cleft. What is the most likely physiological effect?

Accepted Answer

Prolonged muscle contraction due to continued stimulation.

Question 8

Which of the following best explains why cartilage is 'springy' and acts as an effective shock absorber?

Accepted Answer

It is composed of glycosaminoglycans with high negative charge, causing electrostatic repulsion and water retention.

Question 9

Which of the following correctly matches the membrane lipid with its backbone and linkage type?

Accepted Answer

Phosphoglycerides: glycerol backbone, ester linkage

Question 10

Which of the following statements about the fluid-mosaic model of cell membranes is FALSE?

Accepted Answer

Phospholipids and proteins are fixed in place and cannot move.

Question 11

Which of the following best describes the action of aspirin and ibuprofen?

Accepted Answer

They inhibit the enzyme cyclooxygenase, reducing prostaglandin synthesis.

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 exchanges GDP for GTP → Adenylate cyclase is activated → ATP is converted to cAMP

Question 13

Which of the following is a correct description of the difference between steroid and peptide hormone signaling?

Accepted Answer

Steroid hormones bind to cytosolic or nuclear receptors and directly regulate gene expression.

Question 14

Which of the following best describes the products of saponification of a triacylglycerol?

Accepted Answer

Fatty acid salts (soap) and glycerol

Question 15

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

Accepted Answer

Type B blood has an extra galactose attached to the oligosaccharide foundation.

Question 16

Which of the following is a correct statement about the structure and function of cellulose?

Accepted Answer

It is composed of β-D-glucose units linked by β(1→4) bonds and provides structural support in plant cell walls.

Question 17

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

Accepted Answer

Active transport moves molecules against their concentration gradient and requires energy input.

Question 18

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

Accepted Answer

Arachidonic acid

Question 19

Which of the following best explains why sucrose does NOT give a positive Benedict’s test?

Accepted Answer

Both anomeric carbons are involved in the glycosidic bond, so there is no free hemiacetal group.

Question 20

Which of the following is a correct description of the effect of hydrogenation on vegetable oils?

Accepted Answer

It converts some cis double bonds to trans, increasing the melting point and making the fat more solid.

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

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