Question 1

Peroxisomes in liver cells detoxify alcohol by removing hydrogen atoms and combining them with which of the following molecules?

Accepted Answer

Peroxisomes detoxify various substances by transferring hydrogen atoms from the substances to oxygen, forming hydrogen peroxide (H2O2) as a byproduct. This process helps in detoxifying alcohol in liver cells.

Question 2

Which of the following statements best describes some aspect of protein secretion from prokaryotic cells?

Accepted Answer

Prokaryotes, despite lacking an endomembrane system, can secrete proteins. These proteins are synthesized on ribosomes that are free in the cytoplasm, not bound to the plasma membrane as in eukaryotes. However, the statement that comes closest to describing a process related to protein secretion in prokaryotes is the synthesis of proteins on ribosomes, albeit the detail about their attachment to the plasma membrane is more characteristic of eukaryotic cells. Prokaryotic cells do have mechanisms for protein secretion, such as the Sec system and twin-arginine translocation (Tat) pathway, which involve the translocation of proteins across or into the plasma membrane.

Question 3

A newly synthesized protein destined for secretion from a eukaryotic cell will generally follow which of the pathways listed below?

Accepted Answer

The correct pathway for a newly synthesized protein destined for secretion from a eukaryotic cell is from the rough endoplasmic reticulum (ER), where it is synthesized, to the Golgi apparatus for processing, then packaged into a transport vesicle that fuses with the plasma membrane to secrete the protein outside the cell.

Question 4

Tay-Sachs disease is a human genetic disorder that results in cellular accumulation of very large, complex, undigested lipids. Which of the following organelles is most likely defective in Tay-Sachs disease?

Accepted Answer

Tay-Sachs disease is caused by a deficiency in the enzyme hexosaminidase A, which is necessary for breaking down certain lipids in the brain and nerve cells. This enzyme is found in the lysosomes, which are responsible for digesting cellular waste and recycling cellular components. Therefore, the lysosome is the organelle most likely defective in Tay-Sachs disease.

Question 5

The nuclear lamina is an array of intermediate filaments that line the inner surface of the nuclear membrane. Disassembly of the lamina by chemical treatment would most likely result in which of the following consequences?

Accepted Answer

The nuclear lamina provides structural support to the nucleus. Disassembly would likely lead to a change in the shape of the nucleus due to the loss of this support.

Question 6

Which of the following organelles is primarily responsible for the production and modification of polysaccharides that will be secreted?

Accepted Answer

The Golgi apparatus is responsible for modifying, sorting, and packaging proteins and lipids for secretion or delivery to other organelles. It is also involved in the production and modification of polysaccharides.

Question 7

Asbestos is a material that was extensively used in construction for decades. One risk from working in a building that contains asbestos is the development of asbestosis caused by the inhalation of asbestos fibers. Cells will take up asbestos by phagocytosis, but are not able to degrade it. Toxicity most likely results from accumulation of asbestos in which of the following organelles?

Accepted Answer

Asbestos fibers, when inhaled, are engulfed by phagocytes through phagocytosis but cannot be degraded by these cells. The indigestible fibers accumulate in the lysosomes, causing damage and leading to cellular toxicity. This is because lysosomes are the organelles responsible for breaking down waste materials and cellular debris, and their failure to degrade asbestos fibers results in toxicity and inflammation.

Question 8

Examination of a cell by transmission electron microscopy reveals a high density of ribosomes in the cytoplasm. This observation suggests that the cell is actively producing large amounts of which of the following molecules?

Accepted Answer

Ribosomes are the cellular organelles responsible for protein synthesis. A high density of ribosomes in a cell's cytoplasm indicates active protein production.

Question 9

If plant cells are grown on media containing radioactively labeled thymine for one generation, radioactively labeled macromolecules will be detected in which of the following organelles?

Accepted Answer

Thymine is a nucleotide base found in DNA. Since DNA is present in the nucleus, mitochondria, and chloroplasts, radioactively labeled thymine would be incorporated into the DNA of all these organelles during replication.

Question 10

A cell with a predominance of rough endoplasmic reticulum is most likely involved in which of the following processes?

Accepted Answer

The rough endoplasmic reticulum (RER) is studded with ribosomes, which are sites of protein synthesis. Cells with a predominance of RER are typically involved in producing large quantities of proteins for secretion outside the cell.

Question 11

While abundant quantities of proteins are produced by free ribosomes in the cytosol, new proteins are also produced by which of the following organelles?

Accepted Answer

Mitochondria have their own DNA and ribosomes, allowing them to produce some of their own proteins independently of the cell's cytoplasmic ribosomes.

Question 12

Which of the following organelles often occupy the majority of the volume of a plant cell?

Accepted Answer

The central vacuole often occupies the majority of the volume of a plant cell, playing key roles in storage, waste disposal, protection, and growth.

Question 13

Disruption of the function of which of the following organelles would result in a dramatic decrease in ATP synthesis in eukaryotic cells?

Accepted Answer

The mitochondrion is the organelle responsible for the majority of ATP (adenosine triphosphate) synthesis in eukaryotic cells through the process of cellular respiration.

Question 14

Disruption of nuclear pore complexes in a eukaryotic cell will most likely interfere with the transport of which of the following molecules into the nucleus?

Accepted Answer

Ribosomal proteins are synthesized in the cytoplasm and need to be transported into the nucleus to be assembled into ribosomes, a process that requires nuclear pore complexes.

Question 15

Which of the following structures is independent of the endomembrane system in eukaryotic cells?

Accepted Answer

Chloroplasts are not part of the endomembrane system. They are considered part of the plastids family and have their own DNA and ribosomes, functioning somewhat independently within plant and algal cells for photosynthesis. The endomembrane system includes the nuclear envelope, Golgi apparatus, endoplasmic reticulum, and vesicles, but not chloroplasts.

Question 16

An organelle in a newly discovered cell contains thylakoids, DNA, and ribosomes. These findings suggest that this organelle is most likely similar to which of the following organelles?

Accepted Answer

Chloroplasts contain thylakoids (structures involved in photosynthesis), their own DNA, and ribosomes, which are characteristics that match the description of the organelle in the question.

Question 17

An early step in the evolution of eukaryotic cells most likely involved which of the following events?

Accepted Answer

The endosymbiotic theory suggests that mitochondria originated from the engulfment of an aerobic bacterium by a larger host cell. This event is believed to be a critical step in the evolution of eukaryotic cells, allowing them to utilize oxygen for energy production more efficiently.

Question 18

The liver is involved in detoxification of many poisons and drugs. Which of the following structures is abundant in liver cells and primarily responsible for detoxification processes?

Accepted Answer

The smooth endoplasmic reticulum (SER) is abundant in liver cells and plays a crucial role in the detoxification of drugs and poisons. It is involved in the metabolism of lipids and the synthesis of steroid hormones, as well as the detoxification process, making it essential for liver function.

Question 19

Gaucher disease is the most common genetic disorder affecting lipid storage in humans. The disease is caused by deficiency of an enzyme necessary for the breakdown of lipids, which leads to the accumulation of fatty material in organs of the body including the spleen, liver, kidneys, lungs, brain, and bone marrow.
Which of the following statements provides the most plausible explanation for how organelles are impacted by Gaucher disease.

Accepted Answer

Gaucher disease is caused by a deficiency in the enzyme glucocerebrosidase, which is necessary for the breakdown of glucocerebroside, a lipid. This enzyme is found in lysosomes, and its deficiency leads to the accumulation of glucocerebroside in these organelles, affecting their function.

Question 20

A cell with a predominance of smooth endoplasmic reticulum is most likely specialized to carry out which of the following processes?

Accepted Answer

The smooth endoplasmic reticulum (ER) is primarily involved in the synthesis of lipids, metabolism of carbohydrates, and detoxification of drugs and poisons. Therefore, a cell with a predominance of smooth ER is most likely specialized for the synthesis of large quantities of lipids.

Quiz 7: Cell Structure and Function