PCAT PCAT Cell Biology 1 — Questions and Answers
Question 1: Which organelle is the primary site of ATP production through cellular respiration?
- Mitochondria (Correct answer)
- Nucleus
- Ribosome
- Golgi apparatus
Correct answer: Mitochondria
Mitochondria generate most of the cell's ATP through the electron transport chain and oxidative phosphorylation in their inner membrane.
Question 2: What is the primary function of the rough endoplasmic reticulum (rough ER)?
- Protein synthesis and processing (Correct answer)
- Lipid synthesis
- Energy production
- DNA replication
Correct answer: Protein synthesis and processing
The rough ER is studded with ribosomes and is responsible for synthesizing, folding, and processing proteins destined for secretion or membrane insertion.
Question 3: Which cellular structure selectively controls the passage of substances into and out of the cell?
- Plasma membrane (Correct answer)
- Cell wall
- Nucleus
- Cytoskeleton
Correct answer: Plasma membrane
The plasma membrane is a selectively permeable phospholipid bilayer with embedded proteins that regulate what enters and exits the cell.
Question 4: What type of cell division produces two genetically identical diploid daughter cells for growth and tissue repair?
- Mitosis (Correct answer)
- Meiosis
- Binary fission
- Budding
Correct answer: Mitosis
Mitosis produces two identical daughter cells with the same chromosome number as the parent cell, used for somatic growth and repair.
Question 5: Which organelle contains hydrolytic enzymes used to digest cellular waste, damaged organelles, and engulfed pathogens?
- Lysosomes (Correct answer)
- Vacuoles
- Peroxisomes
- Ribosomes
Correct answer: Lysosomes
Lysosomes contain acid hydrolases that break down macromolecules and cellular debris in an acidic interior maintained by proton pumps.
Question 6: What term describes the passive movement of water across a semipermeable membrane toward the region of higher solute concentration?
- Osmosis (Correct answer)
- Active transport
- Facilitated diffusion
- Endocytosis
Correct answer: Osmosis
Osmosis is driven by differences in water potential; water moves passively toward higher solute (lower water) concentration without energy input.
PCAT PCAT Cell Biology 1
Which organelle is the primary site of ATP production through cellular respiration?