Which statement best describes cell theory?
A) Cells only exist in multicellular organisms
B) Cells arise spontaneously
C) Cells are the smallest units that perform all vital physiological functions
D) Cells do not maintain homeostasis
C
The slides state that cells are the smallest units that perform all vital physiological functions and that each cell maintains homeostasis.
What is the main function of the plasma membrane?
A) Protein synthesis
B) Physical isolation and regulation of exchange
C) ATP production
D) DNA storage
B
According to the PPT, the plasma membrane provides physical isolation, regulates exchange, senses the environment, and supports cell structure.
Which membrane component forms a barrier to ions and water-soluble compounds?
A) Cholesterol
B) Proteins
C) Phospholipid bilayer
D) Glycocalyx
C
The hydrophobic fatty-acid tails of the phospholipid bilayer form a barrier to ions and water-soluble substances.
Which type of membrane protein binds and responds to ligands such as hormones?
A) Anchoring proteins
B) Enzymes
C) Receptor proteins
D) Recognition proteins
C
The slides say receptor proteins bind ligands (ions, hormones) and trigger a cellular response.
What is the glycocalyx?
A) A protein channel
B) A lipid bilayer
C) A “sugar coat” on the cell surface
D) A cytoskeletal structure
C
Membrane carbohydrates form a sticky sugar coat called the glycocalyx, which helps with protection, lubrication, and cell recognition.
Which organelle produces about 95% of the cell’s ATP?
A) Golgi apparatus
B) Lysosome
C) Mitochondrion
D) Ribosome
C
The slides clearly state mitochondria produce 95% of ATP needed to keep the cell alive.
Which organelle modifies, packages, and ships proteins?
A) Rough ER
B) Smooth ER
C) Golgi apparatus
D) Lysosome
C
The Golgi apparatus modifies and packages secretions and directs them to their final destination.
Which organelle has ribosomes attached and folds newly made proteins?
A) Smooth ER
B) Rough ER
C) Golgi apparatus
D) Cytoskeleton
B
Why:
The rough ER has ribosomes and is active in protein synthesis and folding.
Which structure increases surface area to improve absorption?
A) Cilia
B) Flagella
C) Microvilli
D) Centrioles
C
Why:
Microvilli are extensions of the plasma membrane that increase surface area for absorption.
What is the function of lysosomes?
A) ATP production
B) Protein synthesis
C) Intracellular digestion and recycling
D) Lipid synthesis
C
Why:
Lysosomes contain digestive enzymes that break down bacteria, damaged organelles, and waste.
Diffusion is best described as:
A) Movement from low to high concentration
B) Movement requiring ATP
C) Net movement from high to low concentration
D) Vesicle-mediated transport
C
Why:
Diffusion is the net movement down a concentration gradient, which requires no energy.
What happens to a cell placed in a hypotonic solution?
A) It shrinks
B) It stays the same
C) It gains water and may rupture
D) It stops diffusion
C
Why:
In a hypotonic solution, water moves into the cell, possibly causing hemolysis.
Osmosis is the diffusion of:
A) Solutes across a membrane
B) Ions through channels
C) Water across a selectively permeable membrane
D) Proteins via vesicles
C
Why:
The PPT defines osmosis as diffusion of water toward the side with higher solute concentration.
Which transport mechanism requires ATP and moves substances in vesicles?
A) Diffusion
B) Facilitated diffusion
C) Vesicular transport
D) Osmosis
C
Why:
Vesicular transport (endocytosis and exocytosis) is an active process that requires ATP.
The sodium-potassium pump moves:
A) 2 Na⁺ out and 3 K⁺ in
B) 3 Na⁺ out and 2 K⁺ in
C) 3 K⁺ out and 2 Na⁺ in
D) Equal numbers of ions
B
Why:
One ATP moves 3 sodium ions out and 2 potassium ions into the cell, exactly as shown in the slides.
The smallest living unit within the human body is:
A) a protein
B) the cell
C) a tissue
D) an organ
E) an organ system
B)
Why: Cells are the basic structural and functional units of life. Tissues, organs, and organ systems are all made of cells.
The watery component of the cytoplasm is called:
A) cytosol
B) protoplasm
C) extracellular fluid
D) interstitial fluid
E) a colloidal gel
: A)
Why: Cytosol is the intracellular fluid portion of the cytoplasm where metabolic reactions occur.
Which structure separates the contents of a human cell from its surrounding medium?
A) cell wall
B) cell membrane
C) plasma membrane
D) plasmalemma
E) both B and D
E)
Why: Cell membrane and plasmalemma are synonyms. Human cells do not have cell walls.
The plasma membrane is composed of:
A) a bilayer of proteins
B) a bilayer of phospholipids
C) carbohydrate molecules
D) carbohydrates and proteins
E) carbohydrates and lipids
B)
Why: The plasma membrane’s basic structure is a phospholipid bilayer with embedded proteins.
Which of the following is not a function of membrane proteins?
A) bind to ligands
B) regulate ion passage
C) act as carriers
D) act as anchors
E) cell nutrient
E)
Why: Membrane proteins help transport, anchor, and recognize substances that are not nutrients themselves.
Functions of the glycocalyx include:
A) lubrication and protection
B) immune system recognition
C) binding extracellular compounds
D) all of the above
E) B and C only
D)
Why: The glycocalyx (carbohydrate coat) protects cells and helps with cell recognition and binding.
Which of the following is not a nonmembranous organelle?
A) lysosomes
B) cilia
C) centrioles
D) ribosomes
E) cytoskeleton
A)
Why: Lysosomes are membrane-bound organelles; the others are nonmembranous.
Tubulin is to microtubules as actin is to:
A) ribosomes
B) microfilaments
C) intermediate filaments
D) flagella
E) microvilli
B)
Why: Actin proteins assemble into microfilaments, just as tubulin assembles into microtubules.
Which cytoskeleton component moves chromosomes during cell division?
A) microfilaments
B) intermediate filaments
C) thick filaments
D) microtubules
E) basal bodies
D)
Why: Microtubules form the mitotic spindle that separates chromosomes.
