ap bio chapters 6-7 test
The active transport pump used to move sodium ions across the membranes of gill cells in a freshwater fish has each of the following characteristics EXCEPT: (A) It uses osmosis to carry sodium ions into the cells. (B) It requires energy. (C) It has a specific binding site for ATP. (D) It has a specific binding site for sodium ions. (E) It is a protein.
(A) It uses osmosis to carry sodium ions into the cells.
Plant cell walls are composed of cellulose, while fungal cell walls are composed of chitin. A group of scientists hypothesize that this difference means the cell wall has largely different functions in plant cells and fungal cells. Alternatively, another group of scientists hypothesize that despite their biochemical differences, plant and fungal cell walls serve similar functions. Which of the following observations would best support the alternative hypothesis described above?
(B) In both plant cells and fungal cells, the cell wall surrounds the outside of the cell membrane.
Cholesterol is an important component of animal cell membranes. Cholesterol molecules are often delivered to body cells by the blood, which transports the molecules in the form of cholesterol-protein complexes. The complexes must be moved into the body cells before the cholesterol molecules can be incorporated into the phospholipid bilayers of cell membranes. Based on the information presented, which of the following is the most likely explanation for a buildup of cholesterol molecules in the blood of an animal?
(B) The animal's body cells are defective in endocytosis.
Organelles such as mitochondria and the endoplasmic reticulum have membranes that compartmentalize reactions and other metabolic processes. To function properly, the organelles must move substances across their membranes. . . Which of the following statements describes a feature shared by mitochondria and the endoplasmic reticulum that increases the efficiency of their basic functions? * (A) They have rigid, nonfluid membranes. (B) They have highly folded membranes. (C) They have membranes composed of many carbohydrates. (D) They have double membranes, with one membrane enclosed within the other.
(B) They have highly folded membranes.
Which of the following experimental changes would allow the scientist to observe transport of a solute across the artificial membrane? (A) Increase the solute concentration in the solution (B) Use a small, nonpolar solute instead of a protein (C) Increase the temperature of the solution (D) Add artificial aquaporins to the membrane
(B) Use a small, nonpolar solute instead of a protein
Which statement best describes the effect on water transport across the cell membrane if the aquaporin in the figure ceases to function?
(B) Water molecules will still be able to move across the cell membrane but at a slower rate.
Aquaporins are channel proteins that facilitate the transport of water across the cell membrane. One group of researchers hypothesizes that without functional aquaporins, no water will be able to enter the cell. A different group proposes an alternative hypothesis, stating that even with nonfunctional aquaporins, a small amount of water will still cross the cell membrane. An experiment is set up in which plant cells with mutated (nonfunctional) aquaporins and plant cells with normally functioning aquaporins are both placed in distilled water. Which of the following data would support the alternative hypothesis?
(D) Cells with mutated aquaporins exhibit moderate turgor pressure and are hypertonic.
Which of the following outcomes will most likely result from a change in the shape of the mitochondrial inner membrane from a highly folded surface to a smooth, flat surface? (A) Mitochondria will become more efficient because the inner mitochondrial membrane will become more permeable to ions. (B) Mitochondria will become more efficient because the total volume of the mitochondria will increase. (C) Mitochondria will become less efficient because the inner mitochondrial membrane will become less permeable to large molecules. (D) Mitochondria will become less efficient because the surface area of the inner mitochondrial membranes will decrease
(D) Mitochondria will become less efficient because the surface area of the inner mitochondrial membranes will decrease
Which of the following statements best supports the claim that certain organelles within eukaryotic cells evolved from free-living prokaryotic cells? * (A) The cytoplasm of both eukaryotes and prokaryotes is surrounded by a plasma membrane. (B) Eukaryotes and prokaryotes both contain ribosomes, but the ribosomes of eukaryotes are more complex in structure than those of prokaryotes. (C) Eukaryotes exchange segments of internal membranes between the endoplasmic reticulum and Golgi apparatus, but prokaryotes have no such internal membranes. (D) Some organelles contain their own DNA that is more similar to prokaryotic DNA in structure and function than to the eukaryotic DNA found in the cell's nucleus.
(D) Some organelles contain their own DNA that is more similar to prokaryotic DNA in structure and function than to the eukaryotic DNA found in the cell's nucleus.
Which statement best explains why correct protein folding is critical in the transmembrane protein shown above?
(Interactions of the hydrophobic and hydrophilic amino acids help to anchor the protein in the membrane.
equation for % change in mass
(final mass - initial mass) / initial mass x 100
How to solve surface area to volume ration
1. height x width = surface 2. height x width x length = volume 3. surface / volume
Researchers propose a model to explain variation in phytoplankton cell sizes in a marine environment. They base their model on the idea that smaller cells absorb nutrients more efficiently. The researchers predict that the mean diameter of phytoplankton cells will change by 50 micrometers for every 5-kilometer increase in distance from the shore because of a gradual decrease in nutrient availability. To test their model, the researchers determine that the phytoplankton cells found closest to shore have a mean diameter of 900 micrometers. . . . Based on the model, what will be the mean diameter of the phytoplankton cells that are found 25 kilometers from shore?
650 micometers
sodium-potassium pump
A special transport protein in the plasma membrane of animal cells that transports sodium out of the cell and potassium into the cell against their concentration gradients.
Which of the following statements best predicts the effect of increasing the permeability of the mitochondrial membranes to large molecules?
ATP production will decrease because of an increase in the occurrence of uncontrolled chemical reaction
An investigator wants to understand whether a newly found membrane protein is involved in membrane transport of a certain particle. Which investigation will help determine whether the new membrane protein is a channel protein involved in membrane transport?
Add more of the proteins to the plasma membrane and measure the rate of the particle movement
How does cholesterol affect membrane fluidity?
At warm temperatures (such as 37°C), cholesterol restrains movement of phospholipids At cool temperatures, it maintains fluidity by preventing tight packing
Of the two cells represented in the figure, which would likely be more efficient at exchanging substances with the surrounding environment? CELL A: 6x25x4 CELL B: 25x3
Cell A, because it has the larger surface-area-to-volume ratio
a process that occurs within the Golgi complex?
Enzymatic modification of newly synthesized integral membrane proteins
Which of the following claims is scientifically accurate and consistent with an observation that a decrease in lysosome production within a cell leads to a decline in mitochondrial activity?
Fewer lysosomes will be available to break down macromolecules to provide the necessary nutrients for cellular respiration
Water always moves from an area of ______________ POTENTIAL to an area of ______________ POTENTIAL.
HIGHER WATER POTENTIAL to an area of LOWER WATER POTENTIAL.
The endosymbiont theory proposes a model for the evolution of mitochondria. According to the model, an ancestral eukaryote engulfed a small, free-living prokaryotic organism. The engulfed prokaryote then formed an endosymbiotic relationship with the eukaryotic host. what supports this
Mitochondria and some prokaryotes share similar metabolic reactions that produce .
The endosymbiont theory proposes a model for the evolution of mitochondria. According to the model, an ancestral eukaryote engulfed a small, free-living prokaryotic organism. The engulfed prokaryote then formed an endosymbiotic relationship with the eukaryotic host. . . . . . Which of the following observations best supports the model?
Mitochondria and some prokaryotes share similar metabolic reactions that produce ATP.
endocytosis types
Phagocytosis ("cellular eating") Pinocytosis ("cellular drinking") Receptor-mediated endocytosis
Cells contain smaller components called organelles that are necessary for a cell's survival. Organelle functions have often been compared to components of larger systems. . . . . .. Which of the following functional differences between the rough and smooth endoplasmic reticulum (ER) is explained by the structural differences between them?
Rough ER can synthesize and package proteins for export, and smooth ER cannot.
Which of the following statements best supports the claim that certain organelles within eukaryotic cells evolved from free-living prokaryotic cells?
Some organelles contain their own that is more similar to prokaryotic in structure and function than to the eukaryotic found in the cell's nucleus.
Based on the model, the newly synthesized protein is transported directly from the endoplasmic reticulum to which of the following?
The Golgi complex
A spherical bacterial cell has a radius of 3 um. The human egg cell has a radius of 100um. . . . . . Which statement correctly indicates the cell that is able to more efficiently exchange materials with the external environment and provides a correct explanation? *
The bacterial cell, because it has the largest surface-to-volume ratio
Muscle cells have high ATP demands. Which of the following is a scientific claim about how the structure of the mitochondria in muscle cells should be different than it is in other cells because of the high energy demands of mitochondria? *
The inner membrane of the mitochondria in muscle cells should have more folds to increase the surface area, allowing more ATP to be synthesized
Which of the following outcomes will most likely result from a loss of ion pump function in the cell's lysosomes?
The internal pH of the lysosomes will increase, which will prevent the activation of hydrolytic enzymes and interfere with the intracellular digestion of food.
Six major functions of membrane proteins
Transport Enzymatic activity Signal transduction Cell-cell recognition Intercellular joining Attachment to the cytoskeleton and extracellular matrix (ECM)
receptor-mediated endocytosis
binding of ligands to receptors triggers vesicle formation
the purpose for % change in mass is
creating an even controll
electrochemical gradient
drive the diffusion of ions across a membrane -chemical force (the ion's concentration gradient) -electrical force (the effect of the membrane potential on the ion's movement)
Which of the following best predicts the effect of not having available to supply energy to this process of active transport of h+?
h+ ions will stop moving through the protein.
prokaryotic cells differ eukaryotic cells by
having a nucleoid and no membrane bound organelles
Hypertonic vs. Hypotonic
higher solute concentration; lower solute concentration|||||| hyper: Solute concentration is greater than that inside the cell; cell loses water Hypo: Solute concentration is less than that inside the cell; cell gains water
what type of fatty acids are found in hotter temps? cooler temps?
hotter temp, saturated cooler temp, unsaturated
plant cell in solutions
hypotonic: *turgid*: tugro pressure; full isotonic: *flaccid*: normal hypertonic: *plasmolyzed*: shrivel; move from cell wall
solute potential (ΨS) = -ICRT
i= ionization constant -Salts (like NaCl) ionize = 2.0 (Na and Cl) -Sugars (like Sucrose) doesn't ionize, so its 1.0 C= Molar Concentration R= pressure constant (0.0831 liter bars/mole K) T= Temperature in Kelvin (273 + C) -Remember to convert!!
electrogenic pump
is a transport protein that generates voltage across a membrane
Water diffuses from the region of ______________ concentration to the region of __________ concentration until the solute concentration is equal on both sides
lower solute to higher solute
A ligand is any
molecule that binds specifically to a receptor site of another molecule
double membrane organelles
nucleus, mitochondria, chloroplast
Cotransport
occurs when active transport of a solute indirectly drives transport of other solutes -Plants commonly use the gradient of hydrogen ions generated by proton pumps to drive active transport of nutrients into the cell
what do ion channels do
open or close in response to a stimulus (gated channels)
what is water potential determined by
pressure and amount of solute
what do all cells have in common
ribosomes, plasma membrane, cytosol, and DNA/chromosomes
what type of cell has a greater surface area to volume ratio
smaller cells
Smooth ER vs Rough ER function
smooth : synthesize lipids, metabolize carbs, detox drugs & poisons, store calcium ions rough : secretion of glycoproteins, distributes transport vesicles, protein synthesis
Tonicity
the ability of a surrounding solution to cause a cell to gain or lose water
Osmoregulation
the control of solute concentrations and water balance, is a necessary adaptation for life in such environments
osmosis
the diffusion of water across a selectively permeable membrane
Researchers claimed that a particular organelle originated from a free-living prokaryotic cell that was engulfed by a larger cell -model shows figure engulfing a smaller cell what supports that claim?
the organelle has a double membrane
diffusion
the tendency for molecules to spread out evenly into the available space
membrane potential
the voltage difference across a membrane Voltage is created by differences in the distribution of positive and negative ions across a membrane
Why are membranes fluid?
they need to be fluid to work properly, because the bilayer needs to move and exchange places.
What do carrier proteins do?
undergo a subtle change in shape that translocases the solute-binding site across the membrane
