Structures and Functions of Cells 1

Which organelle is responsible for modifying and packaging proteins for export?
A. Nucleus
B. Rough ER
C. Golgi apparatus
D. Lysosome

Answer: C (Key: Golgi acts as the "post office," modifying and packaging proteins from the ER.)

What is the primary function of ribosomes attached to the rough ER?
A. Synthesize proteins for intracellular use
B. Produce lipids for energy storage
C. Make proteins for secretion outside the cell
D. Digest cellular waste

Answer: C (Key: Ribosomes on rough ER make proteins for export; free ribosomes make proteins for internal use.)

Which structure is unique to plant cells and functions in photosynthesis?
A. Mitochondria
B. Chloroplast
C. Centrioles
D. Lysosomes

Answer: B (Key: Chloroplasts convert light energy to sugar, unique to plants/algae.)

How does the nuclear envelope regulate cellular activities?
A. By synthesizing ATP
B. By controlling material entry/exit to/from the nucleus
C. By digesting damaged organelles
D. By anchoring the cytoskeleton

Answer: B (Key: The nuclear envelope is a selective barrier for DNA and RNA transport.)

Which organelle is not part of the endomembrane system?
A. Golgi apparatus
B. Mitochondria
C. Rough ER
D. Lysosomes

Answer: B (Key: Mitochondria are energy processors, not involved in protein/lipid transport.)

What is the role of microtubules in cell division?
A. Store calcium ions
B. Guide chromosome movement via centrioles
C. Synthesize steroid hormones
D. Detoxify harmful substances

Answer: B (Key: Microtubules form spindle fibers that separate chromosomes.)

Why are lysosomes called "suicide bags"?
A. They release energy during apoptosis.
B. They digest the cell’s own damaged organelles or the entire cell.
C. They produce proteins for cell death.
D. They store excess water.

Answer: B (Key: Lysosomes trigger programmed cell death (apoptosis) when needed.)

Which evidence supports the endosymbiotic theory?
A. Mitochondria have their own DNA.
B. Ribosomes are found in all cells.
C. The nucleus contains chromatin.
D. Vacuoles store food in plants.

Answer: A (Key: Mitochondria and chloroplasts have prokaryotic-like DNA, supporting their symbiotic origin.)

What is the function of the smooth ER in liver cells?
A. Protein synthesis
B. Detoxification of drugs
C. ATP production
D. Photosynthesis

Answer: B (Key: Liver smooth ER detoxifies substances like alcohol and antibiotics.)

Which cytoskeletal component is primarily responsible for muscle contraction?
A. Microtubules
B. Microfilaments (actin)
C. Intermediate filaments
D. Centrioles

Answer: B (Key: Actin microfilaments enable muscle contraction and cell movement.)