3.8: Chapter Review Questions

Multiple-Choice Section

• Use the end‑of‑chapter multiple‑choice section as a regular self‑check tool, not just before exams.
• Read each item carefully, think about what is really being tested (concept, definition, application, or calculation), and choose the option (A, B, C, or D) that best reflects what you have learned in this chapter.
  • After you read through the chapter, attempt all items without looking at your notes; then return to the chapter to review any you missed or felt unsure about.
  • Afterward, explain to yourself why the correct option is right and why the others are not. Finally, repeat the multiple‑choice section a few days later to see what you truly remember and understand.
• Students who consistently use these prompts in this way typically perform better across the course because they turn reading into active practice.

1. A sodium ion channel spans all the way through the cell’s plasma membrane and provides a tunnel for Na⁺ to move in or out of the cell. Because it is embedded in (and passes through) the membrane, this ion channel is best classified as which type of membrane protein?
   1. Receptor protein
   2. Integral protein
   3. Peripheral protein
   4. Glycoprotein
2. A drop of dye is placed into a beaker of water and, over time, becomes evenly distributed without stirring. The dye molecules are moving:
   1. Up their electrical gradient
   2. Up their electrochemical gradient
   3. Down their pressure gradient
   4. Down their concentration gradient

3. A cell uses energy from ATP to pump ions against their concentration gradient and also uses ATP to engulf large particles such as bacteria. Both of these processes are examples of:
   1. Endocytosis
   2. Passive transport
   3. Active transport
   4. Facilitated diffusion
4. Under the microscope, you notice that part of the endoplasmic reticulum (ER) has many tiny dark dots attached to its surface. This region therefore appears “rough.” These dots are:
   1. Peroxisomes
   2. Ribosomes
   3. Lysosomes
   4. Proteins
5. A cell is actively producing secreted and membrane proteins. Which of the following functions is specifically associated with the rough endoplasmic reticulum during this process?
   1. Production of proteins
   2. Detoxification of certain substances
   3. Synthesis of steroid hormones
   4. Regulation of intracellular calcium concentration
6. A muscle cell is using large amounts of glucose and oxygen and needs a great deal of ATP to keep contracting. Which organelles are primarily responsible for producing large quantities of ATP under these conditions?
   1. Mitochondria
   2. Peroxisomes
   3. Lysosomes
   4. Endoplasmic reticulum
7. A neuron maintains a high concentration of Na⁺ outside the cell and a high concentration of K⁺ inside the cell. To do this, it continuously uses ATP to run the Na⁺/K⁺ pump in its membrane. This pump moves ions:
   1. Down their concentration gradients without ATP
   2. Against their concentration gradients using ATP
   3. Only down their electrical gradients
   4. By simple diffusion through the lipid bilayer
8. A white blood cell encounters bacteria in the tissue fluid. It extends parts of its membrane around the bacteria and engulfs them into vesicles, which then fuse with lysosomes. This specific process of “cell eating” is best described as:
   1. Pinocytosis
   2. Phagocytosis
   3. Receptor-mediated exocytosis
   4. Simple diffusion
9. A researcher observes that a certain hormone binds to a protein on the cell surface, but the protein itself does not form a pore or channel. Instead, upon binding, it activates an internal signaling cascade. This membrane protein is functioning primarily as a:
   1. Ion channel (integral protein)
   2. Receptor protein
   3. Peripheral cytoskeletal protein
   4. Carrier protein for facilitated diffusion
10. Microfilaments, intermediate filaments, and microtubules are three major components of the cytoskeleton. Which feature is common to all three?
    1. They all serve to scaffold the organelles within the cell.
    2. They are all characterized by roughly the same diameter.
    3. They are all polymers of protein subunits.
    4. They all help the cell resist compression and tension to the same extent.
11. A certain genetic disease causes defects in the microtubules of epithelial cells lining the respiratory tract. The cilia in these cells do not beat properly. Which cytoskeletal component is directly affected?
    1. Microfilaments (actin filaments)
    2. Intermediate filaments
    3. Microtubules
    4. Keratin fibers only
12. Both the nucleus and the mitochondria are important organelles in eukaryotic cells. Which feature do they share?
    1. Protein-lined membrane pores in a single membrane
    2. A double membrane surrounding the organelle
    3. The synthesis of ribosomes in their interior
    4. The direct production of all cellular ATP
13. A student examines a nucleus under the electron microscope and focuses on a darker region called the nucleolus. Which structure would most likely be found there?
    1. Chromatin (DNA + histone complex) spread throughout the nucleus
    2. Histones alone
    3. Ribosomes (or ribosomal subunits) being assembled
    4. Nucleosomes arranged into condensed chromosomes
14. A segment of DNA has the base sequence G C T T A T A T on one strand. What is the complementary DNA sequence on the opposite strand?
    1. T A G G C G C G
    2. A T C C G C G C
    3. C G A A T A T A
    4. T G C C T C T C
15. Think about how DNA is packaged in the nucleus. DNA wraps around proteins to form nucleosomes, nucleosomes coil to form chromatin, and chromatin further condenses into chromosomes. Which option correctly orders these structures from least to most complex?
    1. DNA, nucleosome, chromatin, chromosome
    2. Nucleosome, DNA, chromosome, chromatin
    3. DNA, chromatin, nucleosome, chromosome
    4. Nucleosome, chromatin, DNA, chromosome

16. A student looks at a dividing cell under the microscope and sees chromosomes condensed and clearly visible, but not yet lined up in the middle of the cell. Which phase is this?
    1. Interphase
    2. Prophase
    3. Metaphase
    4. Anaphase
17. A cell has chromosomes at opposite poles, and a new nuclear envelope is beginning to form around each set. The chromosomes are starting to decondense. Which phase is this?
    1. Prophase
    2. Metaphase
    3. Anaphase
    4. Telophase
18. In a growing embryo, certain cells divide very rapidly. Which combination promotes faster progression through the cell cycle?
    1. Low cyclin levels and low CDK activity
    2. High cyclin levels and active cyclin-dependent kinases (CDKs)
    3. No cyclins and no CDKs
    4. Only tumor suppressor genes active
19. A gene encoding a membrane protein is being expressed in a liver cell. The first step in using this gene to make a protein is:
    1. Translation of mRNA on a ribosome
    2. Transcription of DNA into pre-mRNA in the nucleus
    3. Replication of the gene during S phase
    4. Export of the protein through the Golgi apparatus
20. A ribosome is bound to an mRNA molecule in the cytoplasm. As it moves along the mRNA, it reads three-nucleotide “words” that specify amino acids. Each “word” is called a:
    1. Anticodon
    2. Codon
    3. Intron
    4. Promoter
21. An mRNA codon reads 5′–AUG–3′. Which amino acid does this codon typically specify, and what is its special role?
    1. Glycine; signals the end of translation
    2. Methionine; usually serves as the start codon
    3. Proline; involved only in collagen synthesis
    4. Tryptophan; only found in bacteria