Question 1

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

Accepted Answer

Water has two hydrogen bond donor sites, two acceptor sites, a permanent dipole, high heat capacity, and a density greater in liquid form.

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 an acidic state; proteins may gain positive charge, altering their interactions.

Question 3

Which of the following is NOT a major class of biological macromolecules essential for life?

Accepted Answer

Vitamins

Question 4

Which linkage correctly matches the biological macromolecule to its monomer and bond type?

Accepted Answer

Polysaccharide – Monosaccharide – Glycosidic bond

Question 5

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

Accepted Answer

Phosphorus (P)

Question 6

A solution has a hydrogen ion concentration of $$1 	imes 10$$^{-6}$$ M. What is the pH of this solution?

Accepted Answer

$$pH = 6$$

Question 7

Which of the following best explains why amphipathic molecules form bilayers in aqueous solutions?

Accepted Answer

Their hydrophilic heads interact with water, while hydrophobic tails avoid water, leading to bilayer formation.

Question 8

Which statement best describes the Brønsted-Lowry definition of acids and bases?

Accepted Answer

Acids are proton donors and bases are proton acceptors.

Question 9

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

Accepted Answer

Ice has a lower density than liquid water because its molecular lattice is more open.

Question 10

Which of the following is a correct real-life application of the effect of pH on biomolecules?

Accepted Answer

Hemoglobin's ability to bind oxygen is affected by blood pH, as changes in pH alter its surface charge and conformation.

Question 11

Which of the following statements about lipids is TRUE?

Accepted Answer

Lipids serve as the major structural element of cellular membranes and can act as hormones.

Question 12

A researcher is studying a macromolecule composed of amino acid subunits linked by peptide bonds. Which class of macromolecule is being studied?

Accepted Answer

Proteins

Question 13

Which of the following best describes the relationship between pH and hydrogen ion concentration?

Accepted Answer

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

Question 14

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

Accepted Answer

Nucleic acid – Nucleotide – Phosphodiester bond

Question 15

Which of the following best explains why the phospholipid bilayer is critical for cell function?

Accepted Answer

It forms a selective barrier due to its amphipathic nature, allowing compartmentalization within cells.

Question 16

Which of the following is a property of water that contributes to its ability to moderate temperature in living organisms?

Accepted Answer

High heat capacity

Question 17

Which of the following ions is NOT typically considered essential for life in the context of biochemistry?

Accepted Answer

$$Pb^{2+}$$

Question 18

A solution has a pH of 5. What is the hydrogen ion concentration $$[H$$^{+}$$] in $$this solution?

Accepted Answer

$$[H$$^{+}$$] = 1 	imes 10$$^{-5}$$ M

Question 19

Which of the following best describes the effect of pH on the overall charge of a protein such as ubiquitin?

Accepted Answer

The overall charge changes with pH, affecting biomolecular interactions.

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