Question 1

Which of the following statements best explains why water is considered a polar molecule?

Accepted Answer

Water has a partial negative charge near the oxygen atom and partial positive charges near the hydrogen atoms due to unequal sharing of electrons.

Question 2

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 3

Which of the following best describes the difference between a covalent bond and an ionic bond?

Accepted Answer

Covalent bonds involve the sharing of electrons, while ionic bonds involve the transfer of electrons.

Question 4

Which of the following molecules is NOT classified as a carbohydrate?

Accepted Answer

Cholesterol

Question 5

A patient with uncontrolled diabetes develops ketoacidosis. Which of the following best explains the physiological basis for this condition?

Accepted Answer

Excessive breakdown of triglycerides leads to the accumulation of ketone bodies, lowering blood pH.

Question 6

Which of the following is a function of phospholipids in the human body?

Accepted Answer

They form the double-layered structure of cell membranes due to their amphipathic nature.

Question 7

Which of the following best describes the role of hydrogen bonds in biological molecules?

Accepted Answer

They are responsible for the double helix structure of DNA and the secondary structure of proteins.

Question 8

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes of an element have the same atomic number but different atomic masses.

Question 9

A buffer system in blood involves the following equilibrium: $$HCO_3^- + H$$^+ \leftrightarrow H_2CO_3$$. What happens when excess acid is added to the blood?

Accepted Answer

Bicarbonate ions neutralize the excess acid, forming more carbonic acid.

Question 10

Which of the following best explains why cellulose cannot be digested by humans?

Accepted Answer

Humans lack the enzyme to break the specific glycosidic bonds in cellulose.

Question 11

Which of the following is a correct pairing of a functional group and its chemical property?

Accepted Answer

Carboxyl group (–COOH): acidic

Question 12

Which of the following best describes the tertiary structure of a protein?

Accepted Answer

It is the folding and bending of the polypeptide chain due to interactions between distant amino acids, forming a specific 3D shape.

Question 13

Which of the following is true regarding the difference between DNA and RNA?

Accepted Answer

DNA is double-stranded and contains deoxyribose, while RNA is single-stranded and contains ribose.

Question 14

Which of the following best describes the process of dehydration synthesis?

Accepted Answer

It forms covalent bonds between monomers by removing a water molecule.

Question 15

Which of the following is a real-life example of the importance of stereoisomers in physiology?

Accepted Answer

Enzymes may only recognize one stereoisomer, such as D-glucose, and not its mirror image.

Question 16

Which of the following best explains why nonpolar molecules do not dissolve in water?

Accepted Answer

Nonpolar molecules lack charged or polar regions to interact with water's polarity.

Question 17

Which of the following is a correct statement about the quaternary structure of proteins?

Accepted Answer

It involves the assembly of multiple polypeptide chains into a functional protein complex.

Question 18

Which of the following best describes the function of prostaglandins in the body?

Accepted Answer

They act as regulatory molecules involved in processes such as inflammation, blood clotting, and uterine contractions.

Question 19

Which of the following is a correct example of a conjugated protein?

Accepted Answer

Hemoglobin, which contains both protein and heme groups.

Chemical Composition of the Body: Molecular Interactions and Organic Molecules

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