Question 1

Which of the following best describes the difference between a dehydration synthesis reaction and a hydrolysis reaction in biological macromolecules?

Accepted Answer

Dehydration synthesis removes a water molecule to form a bond, while hydrolysis adds a water molecule to break a bond.

Question 2

A patient is diagnosed with a genetic disorder that results in the substitution of a single amino acid in the primary structure of hemoglobin. Which of the following best explains how this change can affect the protein's function?

Accepted Answer

A change in the primary structure can alter the protein's folding, potentially disrupting its secondary, tertiary, and quaternary structures, and thus its function.

Question 3

Which of the following functional groups is found in all amino acids and is responsible for their acidic properties?

Accepted Answer

Carboxyl group ($-\mathrm{COOH}$)

Question 4

Which of the following statements about phospholipids is correct?

Accepted Answer

Phospholipids form double-layered sheets in water due to their amphipathic nature.

Question 5

A scientist is comparing the DNA of two species and finds that one has 30% adenine and the other has 20% adenine. According to Chargaff's rules, what can be inferred about the percentage of thymine in each species?

Accepted Answer

The species with 30% adenine will have 30% thymine, and the species with 20% adenine will have 20% thymine.

Question 6

Which type of bond links the monomers in a polynucleotide strand?

Accepted Answer

Phosphodiester bond

Question 7

Which of the following best explains why unsaturated fatty acids tend to be liquid at room temperature?

Accepted Answer

They contain double bonds that create kinks, preventing tight packing of molecules.

Question 8

A mutation causes a change in the DNA sequence coding for a protein, resulting in a different amino acid sequence. Which level(s) of protein structure could be affected by this mutation?

Accepted Answer

Primary, secondary, tertiary, and quaternary structures

Question 9

Which of the following is a correct pairing of a macromolecule with its monomer and the type of bond that links them?

Accepted Answer

Carbohydrate – monosaccharide – glycosidic linkage

Question 10

Which of the following best describes the role of chitin in living organisms?

Accepted Answer

It is a structural polysaccharide in the exoskeletons of arthropods and cell walls of fungi.

Question 11

A researcher is studying a molecule with the following characteristics: it is composed of carbon, hydrogen, and oxygen in a 1:2:1 ratio, and it serves as a major energy source for cells. Which class of biological molecule is the researcher most likely studying?

Accepted Answer

Carbohydrate

Question 12

Which of the following statements about the structure of DNA is correct?

Accepted Answer

DNA consists of two antiparallel strands forming a double helix.

Question 13

Which of the following best explains why a denatured protein often loses its biological function?

Accepted Answer

Denaturation disrupts secondary, tertiary, and quaternary structures, altering the protein's shape and active site.

Question 14

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

Accepted Answer

Catalyzing chemical reactions as enzymes

Question 15

A triglyceride is formed by the reaction of which of the following?

Accepted Answer

One glycerol molecule and three fatty acids

Question 16

Which of the following best describes the difference between starch and cellulose?

Accepted Answer

Starch is composed of $\alpha$-glucose monomers, while cellulose is composed of $\beta$-glucose monomers.

Question 17

Which of the following is a correct statement about the genetic code and protein synthesis?

Accepted Answer

The sequence of nucleotides in DNA determines the sequence of amino acids in a protein.

Question 18

A sample of DNA from a newly discovered organism is found to have 22% guanine. According to Chargaff's rules, what percentage of cytosine should be present?

Accepted Answer

22%

Question 19

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

Accepted Answer

Lipids are not composed of monomers linked by covalent bonds in a repeating pattern.

Question 20

A researcher is analyzing the amino acid sequence of the $\beta$-globin protein in humans, monkeys, and gibbons. She finds that the monkey sequence is more similar to the human sequence than the gibbon sequence is. What evolutionary conclusion can she draw from this data?

Accepted Answer

Monkeys are more closely related to humans than gibbons are.

Structure and Function of Biological Molecules

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