Question 1

Which of the following best explains why water is considered an ideal medium for biochemical reactions in living organisms?

Accepted Answer

Water has a permanent dipole, high heat capacity, and can form multiple hydrogen bonds.

Question 2

A patient is found to have a blood pH of 7.2. Based on the physiological pH range, how would you classify this condition, and what is the likely effect on biomolecular interactions?

Accepted Answer

The patient is in acidosis; proteins may gain positive charge, altering their interactions.

Question 3

Which of the following statements about biological macromolecules is CORRECT?

Accepted Answer

Polysaccharides are composed of monosaccharide monomers linked by glycosidic bonds.

Question 4

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

Accepted Answer

Sulfur

Question 5

A solution has a hydrogen ion concentration of $1 	imes 10^{-5}$ M. What is the pH of this solution?

Accepted Answer

$pH = 5$

Question 6

Which of the following best describes an amphipathic molecule in an aqueous environment?

Accepted Answer

It forms a monolayer, micelle, or bilayer due to having both hydrophilic and hydrophobic regions.

Question 7

Which of the following linkages is found in proteins?

Accepted Answer

Peptide (amide) bond

Question 8

A strong acid is added to water. According to the Brønsted-Lowry definition, what happens?

Accepted Answer

The acid donates a proton to water, forming a hydronium ion.

Question 9

Which of the following is a function of lipids in biological systems?

Accepted Answer

Forming the structural basis of cellular membranes

Question 10

If the pH of a solution changes from 7 to 5, what happens to the hydrogen ion concentration?

Accepted Answer

It increases by a factor of 100.

Question 11

Which of the following best explains why ice floats on water?

Accepted Answer

Ice has a lower density than liquid water due to its open hydrogen-bonded lattice.

Question 12

Which of the following ions is essential for nerve impulse transmission in humans?

Accepted Answer

$\mathrm{K^+}$

Question 13

Which of the following is the correct formula for calculating pH?

Accepted Answer

$pH = -\log [H^+]$

Question 14

Which of the following best describes the relationship between pH and the charge of a protein molecule?

Accepted Answer

As pH increases, proteins tend to become more negatively charged.

Question 15

Which of the following is NOT a direct field that contributes to the study of biochemistry?

Accepted Answer

Astronomy

Question 16

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

Accepted Answer

Hydrophilic heads face outward toward water, hydrophobic tails face inward.

Question 17

Which of the following is a correct pairing of a biological macromolecule with its monomer and linkage?

Accepted Answer

Polysaccharide – Monosaccharide – Glycosidic bond

Question 18

Which of the following best explains why the dielectric constant of water is important for life?

Accepted Answer

It allows water to dissolve many salts and biomolecules by reducing electrostatic interactions.

Question 19

Which of the following is a real-life example of an amphipathic molecule forming a structure in water?

Accepted Answer

Formation of a phospholipid bilayer in cell membranes

Question 20

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

Accepted Answer

Acids are proton donors and bases are proton acceptors.

Introduction to Biochemistry: Chemical Elements, Macromolecules, Water, and pH

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