Question
A certain type of specialized cell contains an unusually large amount of rough endoplasmic reticulum (ER).
Which of the following functions is this cell type most likely specialized to perform?
A. The production and secretion of steroids
B. The destruction of toxic materials produced in other cells of the organism
C. The synthesis of polysaccharides for energy storage
D. The production and secretion of proteins
▶️Answer/Explanation
Ans: D
The cytosolic surface of the rough ER is covered by ribosomes that synthesize proteins that are then transported into the rough ER, then to the Golgi complex, and finally out of the cell.
Question
Which of the following cellular deficiencies would most likely be related to mutations in mitochondrial proteins?
A. The cell is unable to synthesize most proteins required for normal cell functions.
B. The cell is unable to break down toxic materials and would accumulate large volumes of these materials.
C. The cell is able to synthesize proteins, but the proteins would not fold properly and would not contain the correct molecular tags for export from the cell.
D. The cell is unable to complete reactions related to electron transport and ATP production.
▶️Answer/Explanation
Ans: D
The electron transport chain and ATP production are associated with proteins in the inner membrane of the mitochondrion. Nonfunctional proteins in the mitochondrion are likely to result in reduced ATP production.
Question
A scientist is studying the various prokaryotic and eukaryotic species found floating in a sample of water taken from a marine ecosystem.
Which cellular component will be found in the widest range of organisms in the sample?
A. The chloroplast, since all organisms need a source of energy.
B. The ribosome, since all organisms need to synthesize proteins.
C. The mitochondrion, since all organisms need to break down glucose.
D. The cell wall, since all marine organisms need them for support.
▶️Answer/Explanation
Ans: B
Ribosomes are found in all forms of life, allowing for comparison of the widest possible range of plankton species.
Question
Organelles such as mitochondria and the endoplasmic reticulum have membranes that compartmentalize reactions and other metabolic processes. To function properly, the organelles must move substances across their membranes.
Which of the following statements describes a feature shared by mitochondria and the endoplasmic reticulum that increases the efficiency of their basic functions?
A. They have rigid, nonfluid membranes.
B. They have highly folded membranes.
C. They have membranes composed of many carbohydrates.
D. They have double membranes, with one membrane enclosed within the other.
▶️Answer/Explanation
Ans: B
Compared with a smooth membrane, a highly folded membrane has a greater surface area that increases the rate of material transport across the membrane and provides more support for membrane-associated processes.
Question
All eukaryotic cells contain at least one Golgi complex, typically located in the cytoplasm and near the endoplasmic reticulum.
Which of the following best describes a process that occurs within the Golgi complex?
A. Enzymatic modification of newly synthesized integral membrane proteins
B. Synthesis of cytosolic proteins based on the nucleotide sequences of mRNAs
C. Degradation of proteins by hydrolytic enzymes contained within the complex
D. Synthesis of various types of lipids
▶️Answer/Explanation
Ans: A
The Golgi complex is a membrane-bound structure to which some proteins are moved from the rough endoplasmic reticulum, where they are enzymatically modified before being sent to a cellular membrane.