CLEP Biology Cell Organelle Structure/Function 3 — Questions and Answers
Question 1: The inner mitochondrial membrane is highly folded into structures called cristae. What is the primary advantage of this folding?
- It increases the volume of the matrix
- It increases the surface area for ATP synthase and electron transport chain proteins (Correct answer)
- It separates the two mitochondrial genomes
- It allows direct contact with ribosomes
Correct answer: It increases the surface area for ATP synthase and electron transport chain proteins
The folding of the inner membrane into cristae greatly increases the surface area available for the electron transport chain and ATP synthase complexes, maximizing ATP production.
Question 2: A cell line is treated with a drug that dissolves all microtubules. Which process would be most immediately disrupted?
- Translation of mRNA
- Chromosome segregation during mitosis (Correct answer)
- Transcription of DNA
- Glycolysis in the cytoplasm
Correct answer: Chromosome segregation during mitosis
The mitotic spindle, which separates chromosomes during cell division, is composed of microtubules and would be destroyed by such a drug.
Question 3: Which feature distinguishes rough ER from smooth ER under an electron microscope?
- Rough ER has a more tubular shape
- Rough ER is studded with ribosomes on its cytoplasmic surface (Correct answer)
- Smooth ER is connected to the nuclear envelope
- Rough ER contains more lipid bilayers
Correct answer: Rough ER is studded with ribosomes on its cytoplasmic surface
The 'rough' appearance of rough ER comes from the ribosomes attached to its cytoplasmic surface, where membrane and secretory proteins are synthesized.
Question 4: Lysosomes fuse with autophagosomes to degrade damaged organelles in a process called autophagy. What would happen if lysosomal enzymes leaked into the cytoplasm?
- The cell would produce more ATP
- The cell's own proteins and organelles would be digested, leading to cell death (Correct answer)
- Protein synthesis would increase
- The nucleus would replicate faster
Correct answer: The cell's own proteins and organelles would be digested, leading to cell death
Lysosomal hydrolytic enzymes are active at low pH and would digest cellular components if released into the cytoplasm, causing autolysis and cell death.
Question 5: Which structural feature allows the nuclear envelope to regulate the passage of molecules between the nucleus and cytoplasm?
- The double lipid bilayer
- Nuclear pore complexes (Correct answer)
- The nucleolus
- Heterochromatin condensation
Correct answer: Nuclear pore complexes
Nuclear pore complexes are large protein channels that span both membranes of the nuclear envelope and selectively control the transport of molecules in and out of the nucleus.
Question 6: In a plant cell, which organelle contains its own circular DNA and 70S ribosomes, supporting the endosymbiotic theory?
- Central vacuole
- Golgi apparatus
- Chloroplast (Correct answer)
- Smooth endoplasmic reticulum
Correct answer: Chloroplast
Chloroplasts (and mitochondria) contain their own circular DNA and prokaryotic-type 70S ribosomes, providing evidence that they evolved from ancient endosymbiotic bacteria.
Question 7: Which of the following best describes the function of the cell wall in plant cells?
- It controls what enters and exits the cell
- It provides structural support and prevents the cell from bursting due to osmotic pressure (Correct answer)
- It synthesizes cellulose for export only
- It generates energy through photosynthesis
Correct answer: It provides structural support and prevents the cell from bursting due to osmotic pressure
The plant cell wall, made primarily of cellulose, provides rigid structural support and resists the osmotic pressure that would otherwise cause the cell to burst in hypotonic conditions.
CLEP Biology Cell Organelle Structure/Function 3
The inner mitochondrial membrane is highly folded into structures called cristae.
What is the primary advantage of this folding?