Question 1

Which of the following best describes the relationship between biochemistry and other scientific disciplines?

Accepted Answer

Biochemistry integrates concepts from organic chemistry, physical chemistry, physiology, genetics, cell biology, microbiology, nutrition, biophysics, and medical science.

Question 2

Which of the following elements is NOT among the four most abundant elements in living systems?

Accepted Answer

Phosphorus (P)

Question 3

Which of the following ions is essential for life and plays a key role in nerve impulse transmission?

Accepted Answer

Na$^{+}$

Question 4

Which of the following correctly matches a biological macromolecule with its monomer and the type of linkage that joins its monomers?

Accepted Answer

Polysaccharide – Monosaccharide – Glycosidic (ether) bond

Question 5

Which statement best explains why lipids are not considered true polymers?

Accepted Answer

Lipids are not formed by repetitive covalent linkage of identical or similar monomers.

Question 6

A patient is diagnosed with a disorder affecting the structure of their cell membranes. Which class of biological macromolecule is most likely involved?

Accepted Answer

Lipids

Question 7

Which of the following properties of water is primarily responsible for its ability to dissolve ionic compounds such as NaCl?

Accepted Answer

Permanent dipole and high dielectric constant

Question 8

Which of the following best describes an amphipathic molecule?

Accepted Answer

A molecule that contains both hydrophilic and hydrophobic regions

Question 9

A researcher adds a drop of olive oil to water and observes the oil forming droplets. Which property of lipids does this illustrate?

Accepted Answer

Lipids are hydrophobic and aggregate to minimize contact with water

Question 10

Which of the following equations correctly expresses the relationship between hydrogen ion concentration and pH?

Accepted Answer

$\mathrm{pH} = -\log [\mathrm{H}^+]$

Question 11

A solution has a hydrogen ion concentration of $1 	imes 10^{-8}$ M. What is its pH?

Accepted Answer

8

Question 12

Which of the following best explains why water has a higher density in its liquid state than in its solid state?

Accepted Answer

Hydrogen bonds in ice create an open lattice structure, making solid water less dense.

Question 13

Which of the following statements about acids and bases is correct according to the Brønsted-Lowry definition?

Accepted Answer

Acids are proton donors and bases are proton acceptors.

Question 14

A weak acid is added to water. Which of the following best describes what happens?

Accepted Answer

The acid partially dissociates, establishing an equilibrium between the acid and its conjugate base.

Question 15

Which of the following best explains why the surface charge of a protein can change as the pH of the solution changes?

Accepted Answer

The ionization state of amino acid side chains changes with pH, altering the net charge.

Question 16

Which of the following is a real-life example of the importance of physiological pH range (6.5–8.0) in biological systems?

Accepted Answer

Enzyme activity in the human body is optimal only within this pH range.

Question 17

Which of the following best describes the structure of a phospholipid bilayer in biological membranes?

Accepted Answer

Hydrophobic tails face inward, away from water, while hydrophilic heads face outward toward the aqueous environment.

Question 18

A scientist is studying a molecule that can form both hydrogen bonds and ionic interactions in water. Which property of water is most relevant to these interactions?

Accepted Answer

Water's ability to act as both a hydrogen bond donor and acceptor

Question 19

Which of the following best explains why amphipathic molecules can form micelles in aqueous solution?

Accepted Answer

Their hydrophobic regions aggregate to minimize contact with water, while hydrophilic regions interact with water.

Question 20

A solution has a pH of 5. How does its hydrogen ion concentration compare to a solution with pH 7?

Accepted Answer

It is 100 times higher.

Foundations of Biochemistry: Elements, Macromolecules, Water, and pH

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