Chapter 3 - Cellular Level of Organization

Question 1

Because they are embedded within the membrane, ion channels are examples of (BLANK).

A) Receptor proteins.
B) Integral proteins.
C) Peripheral proteins.
D) Glycoproteins.

Answer 1

B) Integral proteins.

Explanation: Ion channels span the membrane, making them integral membrane proteins.

Incorrect Answers:
A) Receptor proteins may not be embedded.
C) Peripheral proteins are attached to the surface, not embedded.
D) Glycoproteins have carbohydrates but aren’t necessarily channels.

Question 2

The diffusion of substances within a solution tends to move those substances (BLANK) their (BLANK) gradient.

A) Up; electrical.
B) Up; electrochemical.
C) Down; pressure.
D) Down; concentration.

Answer 2

D) Down; concentration.

Explanation: Substances diffuse from high to low concentration—down the gradient.

Incorrect Answers:
A) Up is incorrect; diffusion is passive.
B) Active transport moves substances up gradients.
C) Pressure isn’t the typical driver of diffusion.

Question 3

Ion pumps and phagocytosis are both examples of (BLANK).

A) Endocytosis.
B) Passive transport.
C) Active transport.
D) Facilitated diffusion.

Answer 3

C) Active transport.

Explanation: Both require energy to move substances or engulf particles.

Incorrect Answers:
A) Only phagocytosis is endocytosis.
B) Passive transport doesn’t use energy.
D) Facilitated diffusion uses channels but not energy.

Question 4

Choose the answer that best completes the following analogy: Diffusion is to (BLANK) as endocytosis is to (BLANK).

A) Filtration; phagocytosis.
B) Osmosis; pinocytosis.
C) Solutes; fluid.
D) Gradient; chemical energy.

Answer 4

D) Gradient; chemical energy.

Explanation: Diffusion moves substances passively down a gradient; endocytosis requires energy.

Incorrect Answers:
A/B/C) These don’t match the energy vs. passive distinction.

Question 5

How does temperature affect diffusion rate, and why?

A) Higher temperatures increase diffusion rate because molecules move faster.
B) Higher temperatures decrease diffusion rate due to protein denaturation.
C) Lower temperatures increase diffusion rate due to reduced viscosity.
D) Temperature has no effect on diffusion rate.

Answer 5

A) Higher temperatures increase diffusion rate because molecules move faster.

Explanation: Temperature raises molecular kinetic energy, increasing the speed at which particles spread out.

Incorrect Answers:
B) Denaturation is not relevant to passive diffusion.
C) Lower temperatures slow molecular motion.

Question 6

Cytoplasm is to cytosol as a swimming pool containing chlorine and flotation toys is to (BLANK).

A) The walls of the pool.
B) The pool water containing chlorine.
C) The flotation toys.
D) The water.

Answer 6

B) The pool water containing chlorine.

Explanation: Cytosol is the fluid with dissolved substances—like water with chlorine.

Incorrect Answers:
A) Represents a boundary, not the fluid.
C) Analogous to organelles.
D) Lacks the “chlorine” analogy (dissolved content).

Question 7

The rough ER has its name due to what associated structures?

A) Golgi apparatus.
B) Ribosomes.
C) Lysosomes.
D) Proteins.

Answer 7

B) Ribosomes.

Explanation: Ribosomes on the ER surface give it a “rough” look.

Incorrect Answers:
A/C) Other organelles.
D) Proteins are produced, not responsible for texture.

Question 8

Which of the following is a function of the rough ER?

A) Production of proteins.
B) Detoxification of certain substances.
C) Synthesis of steroid hormones.
D) Regulation of intracellular calcium concentration.

Answer 8

A) Production of proteins.

Explanation: Ribosomes on rough ER synthesize proteins.

Incorrect Answers:
B/C/D) Functions of the smooth ER or other organelles.

Question 9

Which of the following is a feature common to all three components of the cytoskeleton?

A) They all serve to scaffold the organelles within the cell.
B) They are all characterized by roughly the same diameter.
C) They are all polymers of protein subunits.
D) They all help the cell resist compression and tension.

Answer 9

C) They are all polymers of protein subunits.

Explanation: All cytoskeletal components are made from protein monomers.

Incorrect Answers:
A) Not all components support scaffolding.
B) Their diameters differ.
D) Not all resist both forces.

Question 10

Which of the following organelles produces large quantities of ATP when both glucose and oxygen are available to the cell?

A) Mitochondria.
B) Peroxisomes.
C) Lysosomes.
D) ER.

Answer 10

A) Mitochondria.

Explanation: Mitochondria are the main site of aerobic respiration.

Incorrect Answers:
B/C/D) Not involved in ATP production.

Question 11

The nucleus and mitochondria share which of the following features?

A) Protein-lined membrane pores.
B) A double cell membrane.
C) The synthesis of ribosomes.
D) The production of cellular energy.

Answer 11

B) A double cell membrane.

Explanation: Both are double-membraned organelles.

Incorrect Answers:
A) Only nucleus has nuclear pores.
C) Ribosomes are made in the nucleolus.
D) Only mitochondria produce energy.

Question 12

What is the primary role of the endomembrane system?

A) To produce energy through cellular respiration.
B) To regulate calcium and iron concentrations.
C) To modify, package, and transport lipids and proteins.
D) To store genetic information.

Answer 12

C) To modify, package, and transport lipids and proteins.

Explanation: The endomembrane system (ER, Golgi, vesicles) works together to process and ship biomolecules.

Incorrect Answers:
A) Energy production is the role of mitochondria.
B) Calcium regulation is associated with smooth ER, not the entire system.
D) Genetic information is stored in the nucleus.

Question 13

Which of the following structures could be found within the nucleolus?

A) Chromatin.
B) Histones.
C) Ribosomes.
D) Nucleosomes.

Answer 13

C) Ribosomes.

Explanation: The nucleolus assembles ribosomal subunits.

Incorrect Answers:
A/B/D) Associated with DNA packaging.

Question 14

Which of the following sequences on a DNA molecule would be complementary to GCTTATAT?

A) TAGGCGCG.
B) ATCCGCGC.
C) CGAATATA.
D) TGCCTCTC.

Answer 14

C) CGAATATA.

Explanation: G pairs with C, C with G, T with A, A with T.

Incorrect Answers:
A/B/D) Do not follow base-pairing rules.

Question 15

Place the following structures in order from least to most complex organization: chromatin, nucleosome, DNA, chromosome.

A) DNA, Nucleosome, Chromatin, Chromosome.
B) Nucleosome, DNA, Chromosome, Chromatin.
C) DNA, Chromatin, Nucleosome, Chromosome.
D) Nucleosome, Chromatin, DNA, Chromosome.

Answer 15

A) DNA, Nucleosome, Chromatin, Chromosome.

Explanation: DNA winds around histones to form nucleosomes → chromatin → chromosomes.

Incorrect Answers:
B/C/D) Misorder structural complexity.

Question 16

Which of the following is part of the elongation step of DNA synthesis?

A) Pulling apart the two DNA strands.
B) Attaching complementary nucleotides to the template strand.
C) Untwisting the DNA helix.
D) None of the above.

Answer 16

B) Attaching complementary nucleotides to the template strand.

Explanation: This is the elongation phase where DNA polymerase adds nucleotides.

Incorrect Answers:
A/C) Part of initiation.

Question 17

Which of the following is not a difference between DNA and RNA?

A) DNA contains thymine whereas RNA contains uracil.
B) DNA contains deoxyribose and RNA contains ribose.
C) DNA contains alternating sugar-phosphate molecules whereas RNA does not contain sugars.
D) RNA is single stranded and DNA is double stranded.

Answer 17

C) DNA contains alternating sugar-phosphate molecules whereas RNA does not contain sugars.

Explanation: RNA does contain sugars (ribose); this statement is false.

Incorrect Answers:
A/B/D) All are accurate distinctions.

Question 18

DNA replication proceeds simultaneously at several sites on the same molecule. What separates the base pair at the start of DNA replication?

A) Ligase.
B) Helicase.
C) DNA polymerase.
D) Topoisomerase.

Answer 18

B) Helicase.

Explanation: Helicase unwinds and separates the DNA strands by breaking hydrogen bonds between base pairs.

Incorrect Answers:
A) Ligase seals DNA fragments.
C) DNA polymerase adds nucleotides after strands are separated.
D) Topoisomerase relieves strain ahead of the replication fork, but doesn’t separate base pairs.

Question 19

Transcription and translation take place in the (BLANK) and (BLANK), respectively.

A) Nucleus; Cytoplasm.
B) Nucleolus; Nucleus.
C) Nucleolus; Cytoplasm.
D) Cytoplasm; Nucleus.

Answer 19

A) Nucleus; Cytoplasm.

Explanation: Transcription (mRNA synthesis) occurs in the nucleus; translation happens at ribosomes in the cytoplasm.

Incorrect Answers:
B/C/D) Incorrect locations.

Question 20

How many “letters” of an RNA molecule, in sequence, does it take to provide the code for a single amino acid?

A) 1.
B) 2.
C) 3.
D) 4.

Answer 20

C) 3.

Explanation: A codon is made of 3 RNA nucleotides.

Incorrect Answers:
A/B/D) Not the correct number of bases.

Question 21

Which of the following is not entirely or mostly made out of RNA?

A) The carriers that shuttle amino acids to a growing polypeptide strand.
B) The ribosome.
C) The messenger molecule that provides the code for protein synthesis.
D) The intron.

Answer 21

D) The intron.

Explanation: Introns are DNA sequences that are transcribed but removed from the mRNA before translation.

Incorrect Answers:
A/B/C) Are types of RNA.

Question 22

The ribosome binds to the mRNA molecule to start translation of its code into a protein. What happens to the small and large ribosomal subunits at the end of translation?

A) They are degraded and replaced before the next translation.
B) They detach from the mRNA and separate from each other.
C) They fuse permanently to form a larger complex.
D) They are recycled back into the nucleolus.

Answer 22

B) They detach from the mRNA and separate from each other.

Explanation: At translation termination, ribosomal subunits disassemble and are reused for other mRNA molecules.

Incorrect Answers:
A) Ribosomes are not degraded after each use.
C) Fusion is temporary and functional only during translation.
D) Ribosomes function in the cytoplasm, not the nucleolus.

Question 23

Which of the following phases is characterized by preparation for DNA synthesis?

A) G0.
B) G1.
C) G2.
D) S.

Answer 23

B) G1.

Explanation: G1 is the first gap phase, preparing for DNA replication.

Question 24

A mutation in the gene for a cyclin protein might result in which of the following?

A) A cell with additional genetic material than normal.
B) Cancer.
C) A cell with less genetic material than normal.
D) Any of the above.

Answer 24

D) Any of the above.

Explanation: Cyclin mutations can disrupt normal cell cycle control, causing overgrowth or defective DNA distribution.

Incorrect Answers:
A/B/C) Are each possible outcomes, but D includes all.

Question 25

What is a primary function of tumor suppressor genes? A) Stop all cells from dividing. B) Stop certain cells from dividing. C) Help oncogenes produce oncoproteins. D) Allow the cell to skip certain phases of the cell cycle.

Answer 25

B) Stop certain cells from dividing. Explanation: Tumor suppressors regulate cell cycle progression when errors are detected. Incorrect Answers: A/C/D) Don’t reflect their regulatory role.

Question 26

Which of the following phases is characterized by an inactive stage? A) G1. B) G0. C) S. D) G2.

Answer 26

B) G0. Explanation: G0 is a resting or inactive phase where cells exit the active cycle and cease to divide. Some cells, like neurons, remain in G0 permanently. Incorrect Answers: A) G1: An active growth phase where the cell prepares for DNA synthesis. C) S: The phase where DNA is actively replicated. D) G2: A second active growth phase where the cell prepares for mitosis.

Question 27

What name is given to the region of attachment for two sister chromatids in a cell? A) Meta plate. B) Centromid. C) Centromere. D) Centrosome.

Answer 27

C) Centromere. Explanation: The centromere is the region where two sister chromatids are joined together, and it serves as the attachment site for spindle fibers during cell division. Incorrect Answers: A) Meta plate: Likely a mistaken reference to the metaphase plate, which is where chromosomes align during metaphase, not where they are attached. B) Centromid: Not a recognized biological term. D) Centrosome: An organelle that organizes the mitotic spindle; not involved in directly holding chromatids together.

Question 28

Mitosis results in two identical diploid cells. What structures form during prophase? A) Chromatids uncoil into chromatin. B) Nuclear envelope reforms. C) Spindle fibers and condensed chromosomes. D) Sister chromatids line up at the metaphase plate.

Answer 28

C) Spindle fibers and condensed chromosomes. Explanation: During prophase, chromatin condenses into chromosomes and spindle apparatus begins to form. Incorrect Answers: A) This happens during telophase. B) The nuclear envelope breaks down in prophase, not reforms. D) Chromosomes align in metaphase, not prophase.

Question 29

Arrange the following terms in order of increasing specialization: oligopotency, pleuripotency, unipotency, multipotency. A) Multipotency, Pleuripotency, Oligopotency, Unipotency. B) Pleuripotency, Oligopotency, Multipotency, Unipotency. C) Oligopotency, Pleuripotency, Unipotency, Multipotency. D) Pleuripotency, Multipotency, Oligopotency, Unipotency.

Answer 29

D) Pleuripotency, Multipotency, Oligopotency, Unipotency. Explanation: Differentiation potential narrows in that order. Incorrect Answers: A/B/C) Misorder the hierarchy.

Question 30

Which type of stem cell gives rise to red and white blood cells? A) Endothelial. B) Epithelial. C) Hematopoietic. D) Mesenchymal.

Answer 30

C) Hematopoietic. Explanation: These stem cells form all blood cell types. Incorrect Answers: A/B/D) Different lineages unrelated to blood.

Question 31

What multipotent stem cells from children are sometimes banked by parents? A) Fetal stem cells. B) Embryonic stem cells. C) Cells from the umbilical cord and from baby teeth. D) Hematopoietic stem cells from red and white blood cells.

Answer 31

C) Cells from the umbilical cord and from baby teeth. Explanation: These are rich in multipotent stem cells often stored for future use. Incorrect Answers: A/B/D) Not accurate in describing common banking sources.

Question 32

(BLANK) is breakdown of cells by their own enzymatic action. A) Multipotency. B) Autopotency. C) Autolysis. D) Diffusion.

Answer 32

C) Autolysis. Explanation: Autolysis refers to the self-digestion or destruction of a cell through the action of its own enzymes, often released from lysosomes. Incorrect Answers: A) Multipotency: Refers to a stem cell’s ability to develop into multiple, but limited, cell types. B) Autopotency: Not a recognized biological term. D) Diffusion: The passive movement of particles from high to low concentration; unrelated to enzymatic breakdown.