A Tour of the Cell Practice Quiz (26 questions)

1. An image is enlarged, but two nearby points still appear as one. Which interpretation best distinguishes magnification from resolution?

A. Magnification determines whether points are distinguishable, while resolution describes image enlargement.

B. Magnification describes image clarity, while resolution determines how large the object appears.

C. Magnification and resolution both describe enlargement, but at different viewing distances.

D. Magnification describes image enlargement, while resolution determines whether nearby points can be distinguished.

Answer: (D)

Explanation

Magnification is the ratio of image size to actual object size, whereas resolution concerns clarity and the ability to distinguish nearby points. Thus, increasing image size does not by itself ensure that two points can be resolved.

2. What happens to chromatin as a cell forms discrete chromosomes?

A. DNA and proteins in the nucleus separate from chromatin into ribosomes.

B. DNA and proteins in the nucleus condense from chromatin into discrete chromosomes.

C. DNA and proteins in the cytosol condense from chromatin into discrete chromosomes.

D. RNA and lipids in the nucleus condense from chromatin into discrete chromosomes.

Answer: (B)

Explanation

Within the nucleus, DNA and proteins form chromatin, which condenses into discrete chromosomes. Ribosomes are protein-synthesizing particles, not structures formed when chromatin condenses.

3. Which set of structures belongs to the endomembrane system, linked through membrane continuity or vesicle transfer?

A. Mitochondria, chloroplasts, ribosomes, peroxisomes, and the plasma membrane

B. Endoplasmic reticulum, centrosomes, ribosomes, peroxisomes, and lysosomes

C. The nuclear envelope, mitochondria, cytoskeleton, Golgi apparatus, and chloroplasts

D. The nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, vacuoles, and plasma membrane

Answer: (D)

Explanation

These membrane-bound compartments are connected either directly through membrane continuity or indirectly by vesicle transfer. Mitochondria and chloroplasts are not members of this system.

4. Which statement correctly describes mitochondria and chloroplasts in relation to the endomembrane system?

A. They have single membranes and lack their own DNA, and they are outside the endomembrane system

B. They have single membranes and their own DNA, and they are part of the endomembrane system

C. They have double membranes but no DNA, and they are part of the endomembrane system

D. They have double membranes and their own DNA, and they are outside the endomembrane system

Answer: (D)

Explanation

Mitochondria and chloroplasts have double membranes and their own DNA, but they are not part of the endomembrane system. The nuclear envelope and ER, by contrast, belong to that system.

5. What enables a lysosome to digest proteins, fats, polysaccharides, and nucleic acids?

A. Oxidative enzymes housed in a membrane-bound sac at about pH 7

B. Hydrolytic enzymes housed in a membrane-bound sac at about pH 5

C. Ribosomes housed in a membrane-bound sac at about pH 8

D. Hydrolytic enzymes released into the cytoplasm at about pH 5

Answer: (B)

Explanation

Lysosomes contain hydrolytic enzymes in a membranous sac with an acidic environment of about pH 5. Oxidative enzymes are associated with a different organelle and do not describe lysosomal digestion.

6. What is a typical limitation of a light microscope when examining cell structures?

A. It uses visible light and glass lenses, but generally cannot resolve most organelles.

B. It uses visible light and glass lenses, and routinely resolves most organelles clearly.

C. It uses electrons and glass lenses, and routinely resolves most organelles clearly.

D. It uses electrons and magnetic lenses, but generally cannot resolve most organelles.

Answer: (A)

Explanation

Light microscopes use visible light and glass lenses and magnify effectively to about 1,000 times, but generally cannot resolve most organelles. Electron microscopes use electrons rather than visible light.

7. A cell rapidly changes its shape while moving vesicles toward a new region; what cytoskeletal property supports this response?

A. Fibers can interact with motor proteins and be dismantled and reassembled as needed

B. Fibers digest vesicles to release materials that reshape the cell

C. Fibers store calcium and use it to propel vesicles through the membrane

D. Fibers form a fixed shell that prevents changes in shape and vesicle movement

Answer: (A)

Explanation

The cytoskeleton guides vesicle movement, works with motor proteins in motility, and can be rapidly dismantled and reassembled to change cell shape. A fixed shell would prevent rather than enable the described shape change.

8. Which statement expresses the shared cellular principle about life and the origin of cells?

A. Organisms may consist of cells, but cells do not descend from earlier cells.

B. Only complex organisms consist of cells, and their cells descend from earlier cells.

C. All organisms consist of cells, but new cells arise independently of earlier cells.

D. All organisms consist of cells, and every cell descends from an earlier cell.

Answer: (D)

Explanation

The cellular principles state that cells are the simplest units that can live, make up all organisms, and descend from pre-existing cells. The claim that new cells arise independently contradicts the principle of descent from earlier cells.

9. Which comparison correctly orders the three main cytoskeletal fiber types by diameter?

A. Microtubules are thickest, intermediate filaments are intermediate, and microfilaments are thinnest

B. Microtubules are thickest, microfilaments are intermediate, and intermediate filaments are thinnest

C. Microfilaments are thickest, intermediate filaments are intermediate, and microtubules are thinnest

D. Intermediate filaments are thickest, microtubules are intermediate, and microfilaments are thinnest

Answer: (A)

Explanation

Microtubules are the thickest fibers, intermediate filaments have an intermediate diameter, and microfilaments are the thinnest. The reversed thickest-to-thinnest ordering of microfilaments and microtubules is a common confusion.

10. How is genetic material organized and regulated within a eukaryotic nucleus?

A. The nucleus contains most cellular genes inside a single-membrane envelope whose pores regulate molecular traffic.

B. The nucleus contains most cellular genes inside a double-membrane envelope whose pores prevent molecular traffic.

C. The nucleus contains most cellular genes outside its envelope, which regulates traffic through membrane-bound organelles.

D. The nucleus contains most cellular genes inside a double-membrane envelope whose pores regulate molecular traffic.

Answer: (D)

Explanation

Most of a eukaryotic cell’s genes are in the nucleus, which is enclosed by a double-membrane envelope with pores regulating molecular entry and exit. A single-membrane envelope does not match the nucleus’s described structure.

11. Which pairing correctly matches each organelle with its main energy-related process?

A. Mitochondria with cellular respiration and ATP generation; chloroplasts with photosynthesis

B. Mitochondria with photosynthesis; chloroplasts with cellular respiration and ATP generation

C. Mitochondria with ATP storage; chloroplasts with cellular respiration

D. Mitochondria with cellular respiration; chloroplasts with cellular respiration and ATP generation

Answer: (A)

Explanation

Mitochondria are sites of cellular respiration, which generates ATP, while chloroplasts carry out photosynthesis in plants and algae. The plausible reversed pairing assigns each process to the wrong organelle.

12. A newly made ER product enters the Golgi apparatus for processing; what route does it follow through the Golgi?

A. It enters at the trans face, is sorted without modification, and returns to the ER through the cis face

B. It enters at the cis face, is modified and sorted, and leaves directly through the nuclear envelope

C. It enters at the cis face, is modified and sorted, and leaves in vesicles from the trans face

D. It enters at the trans face, is modified and sorted, and leaves in vesicles from the cis face

Answer: (C)

Explanation

The cis face receives products from the ER, while the Golgi modifies and sorts them before shipping them from the trans face in transport vesicles. The reversed-face route confuses the receiving and shipping sides.

13. What are ribosomes, and what is their primary function?

A. Protein filaments that maintain nuclear shape and synthesize proteins

B. Membrane-bound compartments made of RNA and lipid that synthesize proteins

C. Particles made of DNA and protein that synthesize ribosomal RNA

D. Particles made of ribosomal RNA and protein that synthesize proteins

Answer: (D)

Explanation

Ribosomes consist of ribosomal RNA and protein and carry out protein synthesis. The nuclear lamina, rather than ribosomes, is the protein structure that helps maintain nuclear shape.

14. Which statement correctly distinguishes prokaryotic cells from eukaryotic cells?

A. Prokaryotes enclose DNA in a nucleus and have membrane-bound organelles; eukaryotes place DNA in a nucleoid and lack those organelles.

B. Prokaryotes lack a nucleus and membrane-bound organelles, with DNA in a nucleoid; eukaryotes enclose DNA in a nucleus and have membrane-bound organelles.

C. Prokaryotes lack membrane-bound organelles but enclose DNA in a nuclear envelope; eukaryotes have organelles but place DNA in a nucleoid.

D. Prokaryotes place DNA in a nucleoid and have membrane-bound organelles; eukaryotes lack a nucleus but enclose DNA in a nuclear envelope.

Answer: (B)

Explanation

Prokaryotic cells lack a nucleus and membrane-bound organelles, and their DNA is located in a nucleoid; eukaryotic cells have a nuclear envelope and membrane-bound organelles. The alternative that puts prokaryotic DNA inside a nucleus reverses the key distinction.

15. A researcher wants a three-dimensional-appearing image of a specimen’s surface rather than its internal structure; which microscope is suited to this task?

A. A scanning electron microscope, which images specimen surfaces with a three-dimensional appearance.

B. A scanning electron microscope, which passes electrons through specimens to reveal internal structure.

C. A transmission electron microscope, which images specimen surfaces with a three-dimensional appearance.

D. A transmission electron microscope, which passes visible light through specimens to reveal internal structure.

Answer: (A)

Explanation

A scanning electron microscope images specimen surfaces and produces a three-dimensional appearance. A transmission electron microscope instead passes electrons through a specimen to study its internal structure.

16. What best describes the cytoskeleton’s basic role in a cell?

A. It is a network of fibers throughout the cytoplasm that organizes structures and anchors many organelles

B. It is a collection of enzymes in the nucleus that copies DNA and organizes cell division

C. It is a layer of lipids outside the cell that controls the movement of organelles

D. It is a membrane-bound compartment that digests materials and anchors many organelles

Answer: (A)

Explanation

The cytoskeleton is a fiber network throughout the cytoplasm that organizes cell structures and activities and anchors many organelles. A membrane-bound digestive compartment describes a lysosome, not the cytoskeleton.

17. A cell needs to detoxify a drug and store calcium; which endoplasmic-reticulum region is best suited to these tasks?

A. The smooth ER, which lacks ribosomes and performs both functions

B. The smooth ER, whose ribosomes produce glycoproteins and membranes

C. The rough ER, which lacks ribosomes and specializes in lipid synthesis

D. The rough ER, whose ribosomes carry out both functions

Answer: (A)

Explanation

Smooth ER lacks ribosomes and participates in drug detoxification and calcium storage. Rough ER is ribosome-studded and is associated with synthesizing glycoproteins and cellular membranes.

18. What structural feature of a mitochondrion increases the surface area of its inner membrane?

A. Openings called pores, which connect the matrix to the cytoplasm

B. Tubules called thylakoids, which fill the matrix

C. Stacks called grana, which line the outer membrane

D. Folds called cristae, which line the inner membrane

Answer: (D)

Explanation

The mitochondrial inner membrane folds into cristae, increasing its membrane surface area. Grana are stacks of thylakoids found in chloroplasts, not folds of a mitochondrial membrane.

19. Which set of structures is present in every cell?

A. A plasma membrane, cytosol, chromosomes carrying genes, and ribosomes

B. A plasma membrane, a nucleus, chromosomes carrying genes, and ribosomes

C. A cell wall, cytosol, chromosomes carrying genes, and a nucleus

D. A plasma membrane, cytosol, membrane-bound organelles, and ribosomes

Answer: (A)

Explanation

All cells have a plasma membrane, cytosol, chromosomes that carry genes, and ribosomes that make proteins. A nucleus is not universal because prokaryotic cells lack one.

20. A protein is synthesized by a ribosome attached to the outside of the endoplasmic reticulum. How is that ribosome classified?

A. It is a free ribosome, located in the cytosol away from cellular membranes.

B. It is a free ribosome, attached to the endoplasmic reticulum or nuclear envelope.

C. It is a bound ribosome, located freely in the cytosol away from cellular membranes.

D. It is a bound ribosome, attached to the endoplasmic reticulum or nuclear envelope.

Answer: (D)

Explanation

Bound ribosomes attach to the outside of the endoplasmic reticulum or nuclear envelope, while free ribosomes synthesize proteins in the cytosol. A ribosome attached to the endoplasmic reticulum is therefore not a free ribosome.

21. A tissue must prevent fluid from leaking between neighboring cells while also allowing direct cytoplasmic communication between some adjacent cells; which junction functions match these needs?

A. Gap junctions fasten cells into strong sheets, while desmosomes form channels for cytoplasmic exchange.

B. Tight junctions form channels between cytoplasms, while desmosomes prevent extracellular fluid from leaking between cells.

C. Desmosomes seal neighboring membranes, while tight junctions form cytoplasmic channels between adjacent animal cells.

D. Tight junctions seal neighboring membranes, while gap junctions form cytoplasmic channels between adjacent animal cells.

Answer: (D)

Explanation

Tight junctions press neighboring membranes together to prevent extracellular-fluid leakage, whereas gap junctions provide cytoplasmic channels between adjacent animal cells. Desmosomes strengthen sheets of cells, but they do not provide the cytoplasmic channels described.

22. Which group contains the domains whose organisms have prokaryotic cells?

A. Protists and fungi

B. Animals and plants

C. Fungi and animals

D. Bacteria and Archaea

Answer: (D)

Explanation

Prokaryotic cells occur in organisms belonging to the domains Bacteria and Archaea. Protists, fungi, animals, and plants have eukaryotic cells.

23. A cell needs to adhere to its surroundings and receive signals through receptors connected to an extracellular network; which structure provides this arrangement?

A. The extracellular matrix, whose proteoglycans contain glycoproteins such as collagen and fibronectin that bind integrins.

B. The plant middle lamella, whose pectin-rich layer binds neighboring primary walls and connects them to integrins.

C. The secondary cell wall, whose cellulose fibers bind fibronectin and form channels through the plasma membrane.

D. The gap-junction network, whose cytoplasmic channels attach collagen fibers to receptors on adjacent cells.

Answer: (A)

Explanation

The extracellular matrix contains proteoglycans and glycoproteins, including collagen and fibronectin, that bind plasma-membrane integrins and support cell adhesion and signaling. The middle lamella attaches adjacent plant cells, but it is not the integrin-binding extracellular network.

24. What combination of functions and materials best describes a plant cell wall?

A. It connects neighboring cells, controls cytoplasmic exchange, and consists mainly of collagen fibers attached to membrane receptors.

B. It regulates cell movement and adhesion, and consists of proteoglycans containing collagen and fibronectin outside the plasma membrane.

C. It provides flexible support, stores water inside the cell, and consists mainly of phospholipids and membrane-bound carbohydrates.

D. It protects the cell, maintains its shape, limits excessive water uptake, and contains cellulose fibers embedded in a matrix of polysaccharides and proteins.

Answer: (D)

Explanation

The plant cell wall provides protection and shape, helps prevent excessive water uptake, and is built from cellulose fibers embedded in polysaccharides and proteins. The extracellular matrix option describes an animal-cell structure rather than the composition of a plant cell wall.

25. Which movement pattern distinguishes cilia from flagella?

A. Cilia propel cells with undulating waves, whereas flagella beat with power and recovery strokes

B. Cilia beat with power and recovery strokes, whereas flagella propel cells with undulating waves

C. Cilia and flagella both propel cells through the same undulating wave pattern

D. Cilia and flagella both move through repeated power and recovery strokes

Answer: (B)

Explanation

Cilia beat with distinct power and recovery strokes, while flagella propel cells using undulating waves. Reversing these patterns assigns the characteristic ciliary stroke to flagella.

26. Which evolutionary origin does the endosymbiont theory propose for chloroplasts?

A. They formed from vesicles released by the Golgi apparatus

B. They descended from photosynthetic prokaryotes

C. They developed from infoldings of the nuclear envelope

D. They descended from oxygen-using, non-photosynthetic prokaryotes

Answer: (B)

Explanation

The theory proposes that chloroplasts descended from photosynthetic prokaryotes. Oxygen-using, non-photosynthetic prokaryotes are instead proposed as the ancestors of mitochondria.