Q: A solution has a pH of 4. What is the concentration of hydrogen ions ($$[\mathrm{H}^+]) in $$the solution?

$$[\mathrm{H}^+] = 1 \times 10$$^{-4}$$\ \mathrm{M}$$

Question 1

Which of the following best describes the structure of the phospholipid bilayer in the plasma membrane?

Accepted Answer

A double layer of phospholipids with hydrophilic heads facing outward and hydrophobic tails facing inward.

Question 2

A red blood cell is placed in a hypotonic solution. What will most likely happen to the cell, and why?

Accepted Answer

The cell will swell and possibly burst because water will move into the cell by osmosis.

Question 3

Which of the following is an example of active transport across a cell membrane?

Accepted Answer

Sodium-potassium pump moving Na$$^+$$ out and K$$^+$$ into the cell using ATP.

Question 4

Which of the following best describes the function of a buffer in biological systems?

Accepted Answer

A buffer maintains a stable pH by accepting or donating hydrogen ions as needed.

Question 5

Which of the following functional groups is responsible for the acidic properties of amino acids?

Accepted Answer

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

Question 6

Which of the following best explains why enzymes lower the activation energy ($$E_a) of a $$reaction?

Accepted Answer

They provide a surface for reactants to come together in the correct orientation.

Question 7

A solution has a pH of 4. What is the concentration of hydrogen ions ($$[\mathrm{H}^+]) in $$the solution?

Accepted Answer

$$[\mathrm{H}^+] = 1 	imes 10$$^{-4}$$\ \mathrm{M}$$

Question 8

Which of the following statements about isomers is correct?

Accepted Answer

Isomers are molecules with the same molecular formula but different structures.

Question 9

Which of the following best describes the difference between competitive and noncompetitive enzyme inhibition?

Accepted Answer

Competitive inhibitors bind to the active site, while noncompetitive inhibitors bind to a different site on the enzyme.

Question 10

Which of the following is a correct pairing of a macromolecule type with its monomer and function?

Accepted Answer

Carbohydrate – monosaccharide – energy storage

Question 11

Which of the following reactions is an example of a dehydration synthesis reaction?

Accepted Answer

Joining two amino acids to form a dipeptide and releasing water.

Question 12

Which of the following best describes the role of $$9;\Delta G ($$Gibbs free energy change) in a biochemical reaction?

Accepted Answer

$$\Delta G$$ indicates whether a reaction is spontaneous or requires energy input.

Question 13

Which of the following best explains why water is considered a universal solvent in biological systems?

Accepted Answer

Water can dissolve many substances due to its polarity and ability to form hydrogen bonds.

Question 14

Which of the following best describes the relationship between the structure and function of carbohydrates?

Accepted Answer

The branched structure of glycogen allows for rapid release of glucose.

Question 15

A patient is diagnosed with a genetic disorder that affects the structure of their cell membranes. Which component is most likely altered, leading to decreased membrane fluidity at low temperatures?

Accepted Answer

Cholesterol molecules embedded in the membrane

Question 16

Which of the following best explains the effect of adding a strong acid to a buffered solution?

Accepted Answer

The pH will remain relatively stable because the buffer will absorb excess H$$^+$$ ions.

Question 17

Which of the following is a correct description of allosteric regulation of an enzyme?

Accepted Answer

A molecule binds to a site other than the active site, changing the enzyme's shape and activity.

Question 18

Which of the following best describes the difference between alpha and beta glucose in carbohydrates?

Accepted Answer

Alpha and beta glucose differ in the orientation of the hydroxyl group on carbon 1.

Question 19

Which of the following best explains feedback inhibition in metabolic pathways?

Accepted Answer

The end product of a pathway inhibits an enzyme that acts early in the pathway.

General Biology: Cell Structure, Membrane Transport, Biochemistry, and Enzyme Function

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