Question 1

Which of the following best describes the directionality of a DNA strand, and what chemical groups are found at each end?

Accepted Answer

DNA strands run from the 5′ phosphate group to the 3′ hydroxyl group.

Question 2

Which type of glycosidic bond is found in cellulose, and why can't mammals digest it?

Accepted Answer

Cellulose contains β(1→4) glycosidic bonds, and mammals lack the enzyme to break β bonds.

Question 3

Which of the following statements about complementary base pairing in DNA is correct?

Accepted Answer

Guanine pairs with cytosine via three hydrogen bonds.

Question 4

A patient is diagnosed with a genetic disorder affecting the synthesis of sphingolipids. Which cellular structure is most likely to be affected?

Accepted Answer

The outer leaflet of the plasma membrane

Question 5

Which of the following best explains why unsaturated fatty acids are typically liquid at room temperature?

Accepted Answer

They contain double bonds that introduce bends, preventing tight packing.

Question 6

Which of the following is a correct formula for a hexose sugar, and what is the general formula for carbohydrates?

Accepted Answer

$$\mathrm{C_6H_{12}O_6$}$$; $$\mathrm{C_nH_{2n}O_n}$$

Question 7

Which of the following disaccharides is composed of glucose and galactose, and what type of glycosidic bond does it contain?

Accepted Answer

Lactose; β glycosidic bond

Question 8

A mutation causes a plant to produce only amylose and no amylopectin. Which of the following would be affected?

Accepted Answer

The plant would lack branched starch molecules.

Question 9

Which of the following best describes the structure of a steroid molecule?

Accepted Answer

A four-ringed hydrocarbon skeleton

Question 10

Which of the following is a function of glucocorticoids such as cortisol?

Accepted Answer

Promotion of glucose synthesis and suppression of inflammation

Question 11

Which of the following best explains why triacylglycerols are efficient energy storage molecules?

Accepted Answer

They are highly reduced and yield a large amount of energy upon oxidation.

Question 12

Which of the following is a distinguishing feature of terpenes compared to other lipid classes?

Accepted Answer

They are synthesized from isoprene units.

Question 13

Which of the following best describes the difference between aldosugars and ketosugars?

Accepted Answer

Aldosugars have a terminal carbonyl group; ketosugars have an internal carbonyl group.

Question 14

Which of the following is true about the structure of B-DNA in cells?

Accepted Answer

It consists of two antiparallel and complementary strands forming a right-handed helix.

Question 15

Which of the following best explains why glycolipids are important for cell recognition?

Accepted Answer

They contain carbohydrate groups that serve as recognition sites on the plasma membrane.

Question 16

Which of the following is a correct description of the amphipathic nature of phospholipids?

Accepted Answer

They have both a hydrophilic head and a hydrophobic tail.

Question 17

A mutation in a bacterial cell prevents the synthesis of N-acetylmuramic acid. Which structure would be most directly affected?

Accepted Answer

The peptidoglycan layer of the cell wall

Question 18

Which of the following best explains the structural difference between starch and cellulose?

Accepted Answer

Starch contains α(1→4) glycosidic bonds, while cellulose contains β(1→4) glycosidic bonds.

Question 19

Which of the following is a correct statement about the storage of glycogen in animals?

Accepted Answer

Glycogen is stored mainly in the liver and muscle tissues.

Macromolecules of the Cell: Nucleic Acids, Polysaccharides, and Lipids

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