Organelles&Evidence
This organelle’s internal membranes increase surface area for cellular respiration; it is the site of the electron transport chain in eukaryotes.
What is the mitochondrion?
In the fluid mosaic model, this class of molecules forms the basic bilayer due to amphipathic properties
What are phospholipids?
Movement of a solute down its concentration gradient through a membrane protein without ATP is
What is facilitated diffusion?
As a cell’s radius increases, this ratio decreases, limiting exchange with the environment.
What is the surface area-to-volume ratio?
The variable deliberately changed by a researcher is the
What is the independent variable?
A student isolates an organelle fraction that contains ribosomes attached to membranes and produces secreted proteins. Identify the organelle.
What is the rough endoplasmic reticulum?
A membrane becomes less fluid at low temperatures. This molecule helps maintain fluidity by preventing tight packing of fatty acid tails.
What is cholesterol?
A red blood cell placed in a hypertonic solution will
What is lose water and shrink?
Compared with a spherical cell of equal volume, a highly folded cell membrane most directly improves
What is diffusion/transport efficiency across the membrane (exchange of materials)?
In a dialysis-tubing osmosis lab, the tubing is best used as a model of the
What is the selectively permeable cell membrane?
In an experiment, a eukaryotic cell line is treated with a drug that disrupts microtubule polymerization. The process most directly affected is
What is chromosome separation during mitosis (spindle formation/function)?
A cell exposed to a lipid-soluble signaling molecule shows rapid changes in gene expression without activating a second-messenger cascade. The receptor is most likely
What is an intracellular (cytoplasmic/nuclear) receptor?
A toxin blocks Na⁺/K⁺ ATPase. Over time, the MOST direct consequence for many animal cells is
What is disruption of membrane potential?
A student models diffusion time as proportional to size. This best explains why large cells often
What is less efficient?
A student measures mass change of potato cores in sucrose solutions of different molarity. The dependent variable is
What is the change in mass (or percent mass change) of the potato cores?
A newly discovered eukaryote has organelles with circular DNA and 70S ribosomes. This evidence most strongly supports which theory of origin?
What is the endosymbiotic theory?
Two membranes have identical phospholipid composition, but membrane A has more unsaturated tails. Compared to B, membrane A will be
What is more fluid (especially at lower temperatures)?
A researcher adds a competitive inhibitor to a carrier protein involved in facilitated diffusion. At high solute concentration, transport rate will
What is decrease due to competition for binding sites?
Plant root hairs and intestinal microvilli are examples of structures that primarily increase
What is surface area for absorption?
A researcher repeats a transport experiment with three replicates per condition.Does this improve accuracy or precision?
What is accuracy?
Researchers tag a protein with a signal peptide that targets it to be secreted. List the MOST likely pathway (order) of organelles it passes through.
What is rough ER → Golgi apparatus → secretory vesicle → plasma membrane (exocytosis)?
A student removes peripheral membrane proteins but leaves integral proteins intact. Which membrane function is MOST likely unchanged?
What is selective permeability?
A hormone triggers insertion of aquaporins into the membrane of kidney tubule cells. This change most directly increases
What is water permeability (rate of osmosis)?
Two cells have the same membrane surface area, but cell A has greater volume. Compared to cell B, cell A will generally have
What is slower exchange per unit volume and greater difficulty meeting metabolic demands due to lower SA:V ratio?
A student claims: 'Because the graph shows correlation between membrane protein density and transport rate, the proteins cause the rate increase.' The best graph for this data is
What is a line graph?