AP Biology Chapter 2 Flashcards

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Questions and Answers

Which of the following results, one hour after membrane fusion, best supports the alternative hypothesis that the cell membrane is a fluid mosaic? (Select all that apply)

The membrane of the cell has only grey proteins embedded in it.

The membrane of the cell has only black proteins embedded in it.

The membrane of the cell has both grey proteins and black proteins embedded in it. The grey proteins and black proteins are distributed throughout the cell membrane and are not concentrated in particular areas. (correct)

The membrane of the cell has both grey proteins and black proteins embedded in it. The black proteins are concentrated in one area of the cell membrane, and the grey proteins are concentrated in a separate area of the cell membrane.

Which of the following data would best refute the alternative hypothesis that small nonpolar molecules require channel and transport proteins to move across the cell membrane? (Select all that apply)

Ethanol is found in the cytosol of cells when they are briefly exposed to a ten percent ethanol solution.

Sodium ions cannot move across the cell membrane when membrane protein activity is blocked.

CO2 and N2 movement in and out of cells is unaffected when membrane protein activity is blocked. (correct)

Cells become oxygen deficient when membrane protein activity is blocked.

Which of the following functions is a certain type of specialized cell with an unusually large amount of rough endoplasmic reticulum most likely specialized to perform?

The production and secretion of proteins (correct)

The production and secretion of steroids

The destruction of toxic materials produced in other cells of the organism

The synthesis of polysaccharides for energy storage

Which of the following cellular deficiencies would most likely be related to the MT-ND1 mutations identified in mitochondrial DNA?

The cell is unable to complete reactions related to electron transport and ATP production. Signup and view all the answers

Which cellular component will be found in the widest range of organisms in a marine ecosystem sample?

The ribosome, since all organisms need to synthesize proteins. Signup and view all the answers

What conclusion about the radiolabeled amino acid is best supported by the results of the experiment?

It was mostly incorporated into proteins that regulate and manage metabolic reactions. Signup and view all the answers

Which claim about the effects of the valinomycin treatment on skeletal muscle cells is best supported by the data?

The valinomycin treatment caused a decrease in the activity of the mitochondria. Signup and view all the answers

What conclusion about increasing the number of folds in the inner mitochondrial membrane is best supported by the results of the experiment?

It increases the surface area available for ATP production, which results in faster cell growth. Signup and view all the answers

Based on the provided data, which cell is likely to be most effective in the exchange of materials?

Cell 2 Signup and view all the answers

What provides an accurate calculation of the surface area to volume ratio of an HS red blood cell and its effect on oxygen transferring efficiency?

The ratio is 0.89, and the cells are less efficient at transferring oxygen. Signup and view all the answers

How does the ratio of the density of stomata per CO2 concentration change as the CO2 concentration increases?

The ratio decreases from 0.86 to 0.63, because fewer stomata are needed at higher CO2 concentrations. Signup and view all the answers

Where does testosterone enter a cell and why is it able to cross at that point?

1, because testosterone is nonpolar and can diffuse through the membrane. Signup and view all the answers

Which statement best describes the relationship between regions 1 and 2 of the protein embedded in a cell membrane?

Region 1 is hydrophilic because it interacts with an aqueous environment, whereas region 2 is hydrophobic because it interacts with the interior of the membrane. Signup and view all the answers

How do cholesterol molecules most likely interact with the phospholipid bilayer of a cell's plasma membrane?

The polar head of each cholesterol molecule is situated between the heads of the phospholipids, and the nonpolar region extends into the interior of the membrane between the phospholipid tails. Signup and view all the answers

What should a team of students do next to obtain more conclusive data about the effects of IV fluids with different salt concentrations on red blood cells?

Repeat the process with other salt concentrations. Signup and view all the answers

What additional procedure would best help determine whether nutrient movements into bacterial cells are due to active or passive transport?

Use two additional treatments, one containing only ethyl alcohol and one containing only acetate. Include a substance known to block ATP use by the plasma membrane. Compare the graphs of these two treatments to the original graph. Signup and view all the answers

Based on their observations, what should the researchers do to further clarify how the availability of the protein outside the cells affects the rate of endocytosis of the protein?

Incubate the cells in the presence of several different concentrations of the protein. Signup and view all the answers

Which of the following best predicts what will happen to the lysosomal enzymes if the proteins that transport H+ ions from the cytosol into the lysosome are damaged?

The lysosomal enzymes will not become active, since there will be no active transport of H+ ions. Signup and view all the answers

Which of the following transport mechanisms will be affected most directly by a temporary shortage of ATP molecules inside the cell?

The transport of glucose molecules against a concentration gradient. Signup and view all the answers

Based on the model presented in Figure 1, which of the following changes will most likely result from a depletion of available ATP stores inside the cell?

The Na+ concentration inside the cell will increase. Signup and view all the answers

Which of the following statements best explains why some substances can pass through an actual cell membrane much faster than they passed through an artificial membrane?

Actual cell membranes have a variety of proteins embedded in the membrane that are absent in the artificial membrane. Signup and view all the answers

By which of the following mechanisms do water molecules most likely move into the large intestine after taking magnesium sulfate orally?

By passive transport from an area of low osmolarity to an area of high osmolarity. Signup and view all the answers

How does aldosterone most likely enter target cells?

By simple diffusion. Signup and view all the answers

Which of the graphs below best represents the predicted change in mass over time of the dialysis bag in the beaker to which albumin was added?

The graph indicates no change in mass for the first 30 minutes and then shows an increase in mass. Signup and view all the answers

Which prediction of the effect of lysosome membrane rupture is most likely correct?

Hydrolytic enzymes will be released, which will cause cell death. Signup and view all the answers

Gaucher disease results most directly from a defect in the function of which of the following organelles?

The lysosome. Signup and view all the answers

Which of the following observations best supports the model that chloroplasts evolved from a small prokaryotic organism engulfed by an ancestral eukaryote?

Chloroplasts and some prokaryotes share similar photosynthetic reactions. Signup and view all the answers

Which observation best supports the claim that mitochondria evolved from once-free-living prokaryotic cells by the process of endocytosis?

Mitochondria are surrounded by a double membrane. Signup and view all the answers

Which of the following claims about the origin of the euglenid chloroplast is best supported by the three-membrane structure of the envelope?

It originated from the incorporation of a photosynthetic prokaryote into a eukaryotic cell by two endosymbiotic events. Signup and view all the answers

Which result best refutes the alternative hypothesis that selective permeability of beetroot cells is a consequence of the cell wall?

When beetroot cells are placed in a solution with cellulase, the solution remains clear. Signup and view all the answers

The hypothesis states that membrane structure is static and membrane components throughout the bilayer are rigidly bound.

False Signup and view all the answers

Study Notes

Specialized Cells and Rough ER

Cells with high rough ER content are specialized for protein production and secretion.
Rough ER is linked with ribosomes, which synthesize proteins transported to the Golgi complex and then out of the cell.

Mitochondrial Mutations and Cellular Functions

MT-ND1 mutations in mitochondrial DNA lead to nonfunctional proteins and diseases.
Cells with these mutations struggle with electron transport and ATP production.

Common Cellular Components

Ribosomes are ubiquitous across both prokaryotic and eukaryotic organisms since they are essential for protein synthesis.

Radiolabeled Amino Acid Experiment

The highest amount of a radiolabeled amino acid was found in mitochondria, indicating its incorporation into proteins regulating metabolic reactions.

Valinomycin Effects on ATP Production

Valinomycin treatment resulted in decreased ATP production rates in skeletal muscle cells, indicating impaired mitochondrial function.

Mitochondrial Membrane Efficiency

More folds in the mitochondrial membrane increase ATP production efficiency by providing greater surface area for ATP synthase, enhancing cell growth.

Surface Area to Volume Ratio in Cells

Among four eukaryotic cells, the one with a 6:1 surface area to volume ratio is likely the most efficient in material exchange.

Hereditary Spherocytosis (HS) and Oxygen Transfer

HS red blood cells have a surface area to volume ratio of 0.89, making them less efficient at oxygen transfer compared to normal cells with a ratio of 1.49.

Stomata Density and CO2 Concentration

Stomata density decreases as CO2 concentration increases, indicating fewer stomata are necessary at higher CO2 levels.

Steroid Hormone Movement Across Membrane

Testosterone, being a nonpolar steroid, can easily diffuse through the cell membrane's lipid bilayer.

Hydrophilic and Hydrophobic Protein Regions

A membrane protein's exterior is hydrophilic while the part interacting with fatty acid tails is hydrophobic, aligning with the properties of the phospholipid bilayer.

Cholesterol in Cell Membranes

Cholesterol molecules interact with phospholipid bilayers by placing polar heads between phospholipid heads, while nonpolar regions embed within the bilayer.

IV Therapy and Red Blood Cell Research

IV therapy involves studying the effects of different salt concentrations on red blood cells, with findings indicating that research should extend to other concentrations for conclusive data.

Transport Mechanisms in Bacteria

The transport rate of ethyl alcohol and acetate into bacteria should be compared with ATP-blocking treatments to determine if the transport is active or passive.

Endocytosis and Protein Availability

To study how protein availability affects endocytosis rates, researchers should experiment with varying concentrations of the protein.

Lysosomes and pH Regulation

Damaging H+ transport proteins in lysosomes will prevent activation of lysosomal enzymes since their activity depends on a lower pH achieved through active transport of H+ ions.### Transport Mechanisms and ATP Dependence
Active transport is essential for moving molecules against concentration gradients, requiring ATP energy input.
A shortage of ATP directly impacts the transport of glucose molecules, leading to increased intracellular Na+ concentrations as pumps fail to function.

Membrane Proteins and Ion Concentration

Membrane proteins regulate ion concentrations, including Na+ and K+ across plasma membranes.
In the presence of ATP depletion, Na+ ions continue to leak into the cell, leading to increasing concentrations inside the cell.

Cell Membrane Structure and Function

Actual cell membranes feature embedded proteins, enhancing substance movement compared to artificial membranes.
These proteins facilitate both active and passive transport across the membrane.

Water Movement through Aquaporins

Water diffuses into the large intestine from an area of low osmolarity to high osmolarity via aquaporins, demonstrating passive transport processes.

Aldosterone and Membrane Permeability

Aldosterone, a small hydrophobic molecule, enters cells through simple diffusion, aligning with its nonpolar characteristics.

Dialysis and Osmotic Changes

The introduction of a concentrated solution of albumin alters the osmotic environment, leading to mass changes in dialysis bags.

Lysosome Rupture Effects

Disruption of lysosomal membranes releases hydrolytic enzymes, potentially leading to cell death; this mechanism halts viral replication.

Gaucher Disease and Lysosomal Function

Gaucher disease results from defective lysosomal function, preventing lipid breakdown and causing toxic accumulation.

Evolutionary Models of Chloroplasts and Mitochondria

Chloroplasts likely evolved through endosymbiotic events with prokaryotes, evidenced by similar photosynthetic mechanisms.
The double membrane structure of mitochondria supports their evolution from a free-living aerobic bacterium.

Euglenid Chloroplast Structure

The three-membrane structure of euglenid chloroplasts supports two endosymbiotic events, reflecting a complex evolutionary history.

Selective Permeability of Beetroot Cells

The impermeability of betalains in beetroot cells, even after cell wall damage, indicates selective permeability is due to the cell membrane.

Fluid Mosaic Model of Cell Membranes

Membrane fusion experiments revealing mixed protein distribution within the bilayer support the fluid mosaic model of cell membrane structure.

Molecule Movement and Membrane Permeability

Data showing CO2 and N2 passage into cells without membrane proteins refute the necessity of channel proteins for small nonpolar molecule transport, confirming their ability to diffuse freely.

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Description

Test your knowledge on specialized cells and their functions from AP Biology Chapter 2. This quiz focuses on the role of rough endoplasmic reticulum in various cell types. Perfect for preparing for the AP exam!