Q: Which of the following best explains why cellulose cannot be digested by most animals, while starch can be readily broken down for energy?

Cellulose contains $$eta-1$$,4-glycosidic linkages, which most animals lack the enzymes to hydrolyze, whereas starch contains $$ ext{α}-1$$,4-glycosidic linkages that are easily digested.

Question 1

Which of the following best explains why cellulose cannot be digested by most animals, while starch can be readily broken down for energy?

Accepted Answer

Cellulose contains $$eta-1$$,4-glycosidic linkages, which most animals lack the enzymes to hydrolyze, whereas starch contains $$	ext{α}-1$$,4-glycosidic linkages that are easily digested.

Question 2

A scientist isolates a biological macromolecule and determines that it contains the elements C, H, O, N, and P. Which class of macromolecule is this molecule most likely to belong to?

Accepted Answer

Nucleic acids

Question 3

Which of the following statements about the formation of a peptide bond is correct?

Accepted Answer

A peptide bond forms through a condensation reaction, releasing a molecule of water ($$\ce{H2O}) as $$the carboxyl group of one amino acid bonds to the amino group of another.

Question 4

Which of the following best describes the role of cholesterol in animal cell membranes?

Accepted Answer

Cholesterol acts as a buffer, reducing membrane fluidity at high temperatures and preventing solidification at low temperatures.

Question 5

A red blood cell is placed in a solution and swells until it bursts. Which of the following best describes the solution and the process involved?

Accepted Answer

The solution is hypotonic relative to the cell, and water enters the cell by osmosis.

Question 6

Which of the following is a correct comparison between prokaryotic and eukaryotic cells?

Accepted Answer

Eukaryotic cells have membrane-bound organelles, while prokaryotic cells do not.

Question 7

Which of the following best describes the process of cell fractionation and its importance in cell biology?

Accepted Answer

Cell fractionation separates cellular components by size and density using centrifugation, allowing researchers to study the function of individual organelles.

Question 8

Which of the following statements about facilitated diffusion is correct?

Accepted Answer

Facilitated diffusion requires transport proteins but does not require energy input from the cell.

Question 9

Which of the following best explains why phospholipids are described as amphipathic molecules?

Accepted Answer

They have both hydrophilic (phosphate head) and hydrophobic (fatty acid tail) regions.

Question 10

A mutation causes a protein to lose all of its disulfide bridges but leaves hydrogen bonds and ionic interactions intact. Which level of protein structure is most directly affected?

Accepted Answer

Tertiary structure

Question 11

Which of the following is a function of the extracellular matrix (ECM) in animal cells?

Accepted Answer

The ECM provides structural support, helps regulate cell behavior, facilitates cell communication, and anchors cells to one another.

Question 12

Which of the following best describes the difference between active transport and facilitated diffusion across a cell membrane?

Accepted Answer

Active transport moves substances against their concentration gradient using energy, while facilitated diffusion moves substances down their gradient without energy input.

Question 13

Which of the following best describes the three stages of cell signaling?

Accepted Answer

Reception, transduction, and response

Question 14

Which of the following is true regarding the difference between a nucleotide and a nucleoside?

Accepted Answer

A nucleotide consists of a nitrogenous base, a pentose sugar, and one or more phosphate groups, while a nucleoside lacks the phosphate group.

Question 15

Which of the following best explains why compartmentalization is advantageous in eukaryotic cells?

Accepted Answer

It allows for specialized environments and processes to occur simultaneously within the cell.

Question 16

Which of the following is a correct description of the difference between saturated and unsaturated fats?

Accepted Answer

Saturated fats have no double bonds between carbon atoms in their fatty acid chains, making them solid at room temperature; unsaturated fats have one or more double bonds, causing kinks and making them liquid at room temperature.

Question 17

Which of the following best describes the function of an electrogenic pump in a cell membrane?

Accepted Answer

It creates a voltage (membrane potential) across the membrane by actively transporting ions, contributing to the electrochemical gradient.

Question 18

Which of the following is an example of apoptosis in multicellular organisms?

Accepted Answer

The programmed destruction of cells between developing fingers in a human embryo, resulting in separated digits.

Question 19

Which of the following best describes the difference between channel proteins and carrier proteins in the cell membrane?

Accepted Answer

Channel proteins form hydrophilic pores for specific molecules or ions to pass through, while carrier proteins undergo conformational changes to transport substances.

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