Question 1

Which of the following statements best explains why lipids are not considered true polymers?

Accepted Answer

Lipids are formed from smaller molecules but do not consist of long chains of repeating monomers.

Question 2

A dehydration reaction is crucial in the synthesis of biological macromolecules. Which equation correctly represents a dehydration reaction joining two glucose molecules?

Accepted Answer

$$C_6H_{12}O_6$ + C_6H_{12}O_6$ \rightarrow C$$_{12}$$H_{22}O$$_{11} + H_2O$

Question 3

Which of the following is a correct distinction between an aldose and a ketose monosaccharide?

Accepted Answer

Aldoses have a carbonyl group at the end of the carbon chain, while ketoses have it within the chain.

Question 4

Cellulose and starch are both polymers of glucose. What is the key structural difference between them?

Accepted Answer

Starch contains alpha ($$\alpha) 1-4 $$glycosidic linkages, while cellulose contains beta ($$\beta) 1-4 $$linkages.

Question 5

Which of the following best describes the function of enzymes in biological systems?

Accepted Answer

Enzymes act as biological catalysts, speeding up chemical reactions by lowering activation energy.

Question 6

A patient is found to have a high level of cholesterol in their blood. Which class of biological molecule does cholesterol belong to, and what is its structural characteristic?

Accepted Answer

Cholesterol is a steroid, characterized by four fused carbon rings.

Question 7

Which of the following is a correct description of a phospholipid's behavior in water and its biological significance?

Accepted Answer

Phospholipids form double-layered sheets (bilayers) because their hydrophilic heads face water and hydrophobic tails avoid it, forming cell membranes.

Question 8

Which of the following is NOT a component of a nucleotide?

Accepted Answer

A fatty acid

Question 9

A protein is exposed to high temperature and extreme pH, resulting in loss of its three-dimensional structure. What is this process called, and what is the consequence for the protein's function?

Accepted Answer

Denaturation; the protein becomes biologically inactive.

Question 10

Which type of bond is responsible for linking amino acids together in a polypeptide, and what makes this bond unique?

Accepted Answer

Peptide bond; it is a covalent bond formed by dehydration between the amino group of one amino acid and the carboxyl group of another.

Question 11

Which of the following correctly describes the difference between saturated and unsaturated fatty acids?

Accepted Answer

Saturated fatty acids have no double bonds and are solid at room temperature; unsaturated fatty acids have one or more double bonds and are liquid at room temperature.

Question 12

Which of the following is a storage polysaccharide found in animals, and what is its main function?

Accepted Answer

Glycogen; stores glucose for energy in liver and muscle cells.

Question 13

Which level of protein structure is primarily determined by the sequence of amino acids and is encoded by genetic information?

Accepted Answer

Primary structure

Question 14

Which of the following best describes the antiparallel nature of DNA strands?

Accepted Answer

One strand runs 5' to 3', while the other runs 3' to 5'.

Question 15

Which of the following is a correct example of complementary base pairing in DNA?

Accepted Answer

Adenine (A) pairs with thymine (T)

Question 16

A scientist is analyzing the structure of a protein using X-ray crystallography. What is the main purpose of this technique?

Accepted Answer

To visualize the three-dimensional structure of proteins at atomic resolution.

Question 17

Which of the following is a structural polysaccharide found in the exoskeletons of arthropods and the cell walls of fungi?

Accepted Answer

Chitin

Question 18

Which of the following correctly describes the difference between purines and pyrimidines?

Accepted Answer

Purines have a six-membered ring fused to a five-membered ring; pyrimidines have a single six-membered ring.

Question 19

Which process is responsible for breaking down polymers into monomers, and what molecule is required for this reaction?

Accepted Answer

Hydrolysis; water is added.

Ch. 5 The Structure and Function of Large Biological Molecules

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