Q: Which of the following best explains why cellulose cannot be digested by most animals, including humans?

Humans lack the enzymes to break the $eta$-glycosidic linkages found in cellulose.

Question 1

Which of the following statements correctly distinguishes between the four major classes of biological macromolecules?

Accepted Answer

Lipids are the only class that are not true polymers, while carbohydrates, proteins, and nucleic acids are polymers made from monomers.

Question 2

A dehydration reaction is essential in the synthesis of biological polymers. What is the net chemical change during a dehydration reaction?

Accepted Answer

Two monomers are joined together by removing a water molecule: $C_nH_{2n}O_n + C_mH_{2m}O_m \rightarrow C_{n+m}H_{2(n+m)-2}O_{n+m-1} + H_2O$

Question 3

Which of the following best explains why cellulose cannot be digested by most animals, including humans?

Accepted Answer

Humans lack the enzymes to break the $eta$-glycosidic linkages found in cellulose.

Question 4

Which of the following is a correct description of the structure of a phospholipid?

Accepted Answer

A phospholipid consists of a glycerol backbone, two fatty acid tails, and a phosphate group attached to the third carbon of glycerol.

Question 5

Which of the following is the correct sequence of events in gene expression?

Accepted Answer

DNA $\rightarrow$ RNA $\rightarrow$ Protein

Question 6

A patient is diagnosed with sickle-cell disease. Which molecular change is responsible for this condition?

Accepted Answer

A single amino acid substitution in the primary structure of hemoglobin.

Question 7

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

Accepted Answer

Saturated fatty acids have no double bonds between carbon atoms, while unsaturated fatty acids have one or more double bonds.

Question 8

Which of the following is a function of proteins in living organisms?

Accepted Answer

Catalyzing chemical reactions as enzymes.

Question 9

A researcher is studying the structure of DNA and RNA. Which of the following correctly identifies the sugar component in each molecule?

Accepted Answer

DNA contains deoxyribose; RNA contains ribose.

Question 10

Which of the following statements about the levels of protein structure is correct?

Accepted Answer

Tertiary structure is determined by interactions between R groups of amino acids, including hydrogen bonds, ionic bonds, and disulfide bridges.

Question 11

Which of the following best explains why phospholipids form bilayers in water?

Accepted Answer

Phospholipids have hydrophilic heads and hydrophobic tails, causing them to self-assemble into bilayers with tails facing inward and heads facing outward.

Question 12

Which of the following is a correct description of a nucleotide?

Accepted Answer

A nucleotide consists of a nitrogenous base, a pentose sugar, and one or more phosphate groups.

Question 13

Which of the following is true about the structure of DNA?

Accepted Answer

DNA consists of two antiparallel polynucleotide strands forming a double helix.

Question 14

Which of the following is a real-world consequence of a diet high in saturated fats?

Accepted Answer

It may contribute to cardiovascular disease through plaque deposits in blood vessels.

Question 15

Which of the following is a correct statement about hydrolysis?

Accepted Answer

Hydrolysis breaks down polymers into monomers by adding a water molecule: $	ext{Polymer} + H_2O ightarrow 	ext{Monomer}_1 + 	ext{Monomer}_2$

Question 16

Which of the following is a function of polysaccharides in living organisms?

Accepted Answer

Cellulose provides structural support in plant cell walls.

Question 17

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

Accepted Answer

Purines have a double-ring structure, while pyrimidines have a single-ring structure.

Question 18

A protein is exposed to extreme heat and loses its three-dimensional structure. What is the term for this process, and what is the consequence?

Accepted Answer

Denaturation; the protein becomes biologically inactive.

Question 19

Which of the following correctly matches a biological molecule with its monomer?

Accepted Answer

Protein: amino acid

The Structure and Function of Large Biological Molecules

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