Unit 2 Quiz

The following questions refer to the following diagram. For each phrase or sentence, select the labeled part to which it is most closely related. Each option may be used once, more than once, or not at all for each group.

Site of modification and packaging of proteins and lipids prior to export from the cell

C (Golgi apparatus)

Which of the following is evidence that eukaryotes and prokaryotes share a common ancestor?

All eukaryotes and prokaryotes contain ribosomes.

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?

They have highly folded membranes.

All eukaryotic cells contain at least one Golgi complex, typically located in the cytoplasm and near the endoplasmic reticulum.

Which of the following best describes a process that occurs within the Golgi complex?

Enzymatic modification of newly synthesized integral membrane proteins

Which of the following organelles modifies and packages for secretion the materials produced by the ribosomes?

The Golgi apparatus

Liver cells manufacture glycoproteins, while adipose cells store fat. Which of the following subcellular structures is likely to be more prominent in liver cells than in adipose cells?

Golgi apparatus

Contains hydrolytic enzymes associated with the intracellular digestion of macromolecules

Lysosome

Prokaryotic and eukaryotic cells generally have which of the following features in common?

Ribosomes

The figure below illustrates a eukaryotic cell. Which of the following best describes how the three structures indicated by the arrows work together?

To synthesize and isolate proteins for secretion or for use in the cell

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 two cellular organelles in eukaryotes have both electron transport systems and chemiosmotic mechanisms?

Chloroplasts and mitochondria

Which of the following processes is most likely to occur as a result of an animal cell receiving a signal to initiate apoptosis?

Lysosomes will release digestive enzymes into the cytosol.

The following questions refer to the following diagram. For each phrase or sentence, select the labeled part to which it is most closely related. Each option may be used once, more than once, or not at all for each group.

Site of glucose synthesis

B (Chloroplast)

The following questions refer to the following diagram. For each phrase or sentence, select the labeled part to which it is most closely related. Each option may be used once, more than once, or not at all for each group.

 

Site of conversion of chemical energy of glucose to ATP

A (Mitochondria)

A cell is treated with a drug that prevents the formation of new lysosomes. The cell continues to transcribe the genes that code for the hydrolytic enzymes that are normally found in lysosomes and continues to translate the mRNAs for those proteins on membrane-bound ribosomes.

The hydrolytic enzymes are most likely to accumulate in which of the following cellular structures?

Golgi complex

Which of the following statements is true about the Krebs (citric acid) cycle and the Calvin (light-independent) cycle?

They both are carried out by enzymes located within an organelle matrix.

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.

The organelle that is a major producer of ATP and is found in both heterotrophs and autotrophs is the

mitochondrion

Which of the following best explains how the extensive folding of the inner mitochondrial membrane benefits a eukaryotic cell?

It increases the area available for proteins involved in energy transfer.

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.

The function of which of the following organelles directly requires oxygen?

Mitochondrion

For following group of questions first study the description of the situation or data and then choose the one best answer to each question following it and fill in the corresponding oval on the answer sheet.

In the first step of an experiment, rat liver cells were exposed for 5 minutes to amino acids labeled with a radioactive isotope. The cells were then washed to stop any further incorporation of radioactive amino acids. The cells were sampled periodically thereafter, and the radioactivity of a certain protein (protein X) was measured in various cell components, as shown below.

Which of the following correctly shows the order in which protein X moves through the cell?

Endoplasmic reticulum→Golgi apparatus→lysosomes

For following group of questions first study the description of the situation or data and then choose the one best answer to each question following it and fill in the corresponding oval on the answer sheet.

In the first step of an experiment, rat liver cells were exposed for 5 minutes to amino acids labeled with a radioactive isotope. The cells were then washed to stop any further incorporation of radioactive amino acids. The cells were sampled periodically thereafter, and the radioactivity of a certain protein (protein X) was measured in various cell components, as shown below.

In graphing the data from this experiment, the sampling time would be shown on the x-axis because

sampling time is the independent variable

A mutation in the upland cotton plant causes the development of chloroplasts with a single outer membrane and no internal membranes. Which of the following would most likely be observed in chloroplasts of cotton plants with this mutation?

They would be unable to generate the ATP and NADPH needed to make sugars, because these processes occur on membranes within the chloroplast.

The figure above represents a rough endoplasmic reticulum. Which of the following best describes the role of the structure labeled Y?

Structure Y is the location where proteins are synthesized.

Researchers have proposed a model of the process by which a newly synthesized protein is transported to the plasma membrane and secreted into the extracellular space. The model is represented in Figure 1.

Figure 1. A model of the intracellular transport of a newly synthesized secreted protein

Based on the model, the newly synthesized protein is transported directly from the endoplasmic reticulum to which of the following?

The Golgi complex

In an experiment, the efficiency of oxygen exchange across the plasma membrane is being assessed in four artificial red blood cells. The table above lists some properties of those artificial cells. Other conditions being equal, which artificial cell is predicted to be the most efficient in exchanging oxygen with the environment by diffusion?

The cuboidal cell

A student peeled the skins from grapes, exposing cells with membranes that are only permeable to water and small diffusible solutes. The student measured the mass of the peeled grapes. The student then placed each peeled grape into one of five solutions. After 24 hours, the student removed the peeled grapes from the solutions, measured their final mass, and calculated the percent change in mass (Table 1).

TABLE 1. PERCENT CHANGE IN MASS OF PEELED GRAPES IN SOLUTIONS

Solution	Concentration of Solution(weight/volume)	Percent Change in Mass
Distilled water	0%	13.48%
NaCl	20%	−23.39%
Tap water	0.8%	9.46%
Grape juice	2.1%	2.8%
Grape soda	13%	−15.00%

In a second experiment (Table 2), the student placed a peeled grape into a solution containing both small diffusible solutes and solutes to which the membrane is impermeable (nondiffusible solutes).

TABLE 2. CONCENTRATION OF SOLUTES IN SECOND EXPERIMENT

Location	Concentration of Small Diffusible Solutes	Concentration of Nondiffusible Solutes
Inside grape	0.4⁢M	1.2M
In solution	1.6M	0.8M

Which of the following best explains why larger grapes have a different rate of water absorption per gram of mass than smaller grapes do?

The rate is slower because smaller grapes have a larger surface-area-to-volume ratio than the larger grapes do.

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 micrometers

Simple cuboidal epithelial cells line the ducts of certain human exocrine glands. Various materials are transported into or out of the cells by diffusion. (The formula for the surface area of a cube is 6 X S², and the formula for the volume of a cube is S³, where S = the length of a side of the cube.)

Which of the following cube-shaped cells would be most efficient in removing waste by diffusion?

The primary function of the kidney is to exchange molecules across a membrane between the blood and the urine. One type of kidney cell has a basic rectangular shape, except for a single surface, which is lined with tiny, finger-like projections that extend into the surrounding extracellular space.

Which of the following best explains the advantage these projections provide the cell?

The projections increase the surface area–to-volume ratio of the cell, which allows for more efficient nutrient exchange with the environment.

A spherical bacterial cell has a radius of 3�m. The human egg cell has a radius of 100�m.

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.

A student calculated the average surface area-to-volume ratio of four different types of human epithelial cells. The results are shown in the table below.

Cell Type	Surface Area-to-Volume Ratio
Simple squamous	9
Simple cuboidal	6
Simple columnar	4
Simple spherical	3

Based on the data, which type of cell would be best suited for the lining the alveoli of the lungs, where diffusion of carbon dioxide and oxygen must occur very rapidly?

Simple squamous cells

Two different models of a living cell are represented in the figure.

Of the two cells represented in the figure, which would likely be more efficient at exchanging substances with the surrounding environment?

Cell A, because it has the larger surface-area-to-volume ratio.

Which of the following describes the most likely location of cholesterol in an animal cell?

Embedded in the plasma membrane

Which of the following best describes the numbered areas?

Areas 1 and 3 are polar, since the membrane molecules are aligned with water molecules.

The model below shows the structure of a portion of a plasma membrane in an animal cell.

Which statement best explains the orientation of the phospholipid molecules in this model?

The hydrophilic phosphate groups of the phospholipid molecules are attracted to the aqueous internal and external environments.

A model of the plasma membrane showing several biological molecules, including a transmembrane protein, is shown in Figure 1.

Figure 1. Phospholipid bilayer with transmembrane protein

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.

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?

Cells with mutated aquaporins exhibit moderate turgor pressure and are hypertonic.

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?

In both plant cells and fungal cells, the cell wall surrounds the outside of the cell membrane.

The following questions refer to the following diagram. For each phrase or sentence, select the labeled part to which it is most closely related. Each option may be used once, more than once, or not at all for each group.

 

Site of transport of materials into and out of the cell

D (Cell membrane)

Carbon dioxide most likely enters a cell through which of the following processes?

Simple diffusion through the membrane

Certain chemicals, including sodium fluoride (NaF), are capable of inhibiting specific steps of glycolysis. Figure 1 shows the steps of the glycolysis pathway, indicating where various macromolecules enter the pathway as well as the specific reaction inhibited by NaF.

Figure 1. Key steps in the metabolic pathway of glucose

Which of the following describes why a glucose transporter is needed to move glucose into the cell?

Glucose is large and polar and cannot pass through the phospholipid bilayer.

Which of the following best explains how the phospholipid bilayer of a transport vesicle contributes to cellular functions?

The phospholipid bilayer allows the vesicle to fuse with the Golgi apparatus and the plasma membrane, allowing the exocytosis of proteins.

Which of the following best explains how molecules such as O2 and CO2 can move across the membrane of a cell?

The majority of the cell membrane is nonpolar, which allows small, nonpolar molecules to freely cross.

Which of the following statements is true regarding the movement of substances across cell membranes?

Ions are unable to move through the phospholipid bilayer because the nonpolar tail regions of the phospholipids are hydrophobic.

A team of biologists develop a new drug, and one team member hypothesizes that the drug is incapable of freely passing across the plasma membrane and requires the help of membrane proteins to enter cells. Alternatively, another biologist on the team hypothesizes that the drug can diffuse passively across the plasma membrane like O2 and CO2 can.

Which of the following, if true about the drug, best supports the alternative hypothesis that the new drug will exhibit simple diffusion across plasma membranes?

The drug is a small nonpolar molecule.

A student formulated a hypothesis that water-soluble pollutants damage living organisms by increasing the permeability of cellular membranes. To test the hypothesis, the student investigated the effect of isopropanol and acetone on beet root cells. The vacuoles of beet root cells contain large amounts of betacyanin, a water-soluble pigment that is released into the extracellular environment as a result of increased membrane permeability.

The student prepared identical samples of beet root tissue and incubated each sample for 15 minutes in the specific solution for that group. At the end of the incubation period, the student measured the absorbance of 460 nm light for each sample. A greater concentration of betacyanin in the solution surrounding the beet root cells results in a greater absorbance of 460 nm light. The results of the experiment are shown in the table above.

Which of the following graphs is the most appropriate representation of the experimental data?

A student formulated a hypothesis that water-soluble pollutants damage living organisms by increasing the permeability of cellular membranes. To test the hypothesis, the student investigated the effect of isopropanol and acetone on beet root cells. The vacuoles of beet root cells contain large amounts of betacyanin, a water-soluble pigment that is released into the extracellular environment as a result of increased membrane permeability.

The student prepared identical samples of beet root tissue and incubated each sample for 15 minutes in the specific solution for that group. At the end of the incubation period, the student measured the absorbance of 460 nm light for each sample. A greater concentration of betacyanin in the solution surrounding the beet root cells results in a greater absorbance of 460 nm light. The results of the experiment are shown in the table above.

The absorbance of 460 nm light by the treatment solutions

A student formulated a hypothesis that water-soluble pollutants damage living organisms by increasing the permeability of cellular membranes. To test the hypothesis, the student investigated the effect of isopropanol and acetone on beet root cells. The vacuoles of beet root cells contain large amounts of betacyanin, a water-soluble pigment that is released into the extracellular environment as a result of increased membrane permeability.

The student prepared identical samples of beet root tissue and incubated each sample for 15 minutes in the specific solution for that group. At the end of the incubation period, the student measured the absorbance of 460 nm light for each sample. A greater concentration of betacyanin in the solution surrounding the beet root cells results in a greater absorbance of 460 nm light. The results of the experiment are shown in the table above.

The illustration above is a model of a typical beet root cell. Based on the experimental results, which of the following best represents the effect of acetone on the permeability of cellular membranes?

A student formulated a hypothesis that water-soluble pollutants damage living organisms by increasing the permeability of cellular membranes. To test the hypothesis, the student investigated the effect of isopropanol and acetone on beet root cells. The vacuoles of beet root cells contain large amounts of betacyanin, a water-soluble pigment that is released into the extracellular environment as a result of increased membrane permeability.

The student prepared identical samples of beet root tissue and incubated each sample for 15 minutes in the specific solution for that group. At the end of the incubation period, the student measured the absorbance of 460 nm light for each sample. A greater concentration of betacyanin in the solution surrounding the beet root cells results in a greater absorbance of 460 nm light. The results of the experiment are shown in the table above.

The student analyzed the data from the investigation and concluded that the estimate of the mean of one treatment group was unreliable. Which of the following identifies the treatment group most likely to have provided an unreliable estimate of the mean, and correctly explains why the estimate appears unreliable?

Treatment group II; it has a lower than expected mean absorbance and the largest standard error of the mean.

A student formulated a hypothesis that water-soluble pollutants damage living organisms by increasing the permeability of cellular membranes. To test the hypothesis, the student investigated the effect of isopropanol and acetone on beet root cells. The vacuoles of beet root cells contain large amounts of betacyanin, a water-soluble pigment that is released into the extracellular environment as a result of increased membrane permeability.

The student prepared identical samples of beet root tissue and incubated each sample for 15 minutes in the specific solution for that group. At the end of the incubation period, the student measured the absorbance of 460 nm light for each sample. A greater concentration of betacyanin in the solution surrounding the beet root cells results in a greater absorbance of 460 nm light. The results of the experiment are shown in the table above.

Based on the data from the investigation, which of the following is the best scientific question about organisms living in water that is polluted with organic solvents?

Will organisms living in polluted environments exhibit detrimental effects from an increased permeability of their cellular membranes?

The manner in which several different ions and molecules move through a cell membrane is shown in the diagram above. For each ion or molecule, the relative concentration on each side of the membrane is indicated. Which of the following accurately describes one of the movements taking place?

Na⁺ transport out of the cell requires ATP hydrolysis.

Figure 1 shows a model of how a channel protein influences the movement of a particle across a cell’s plasma membrane.

Figure 1. A section of a cell’s plasma membrane, showing a channel protein and a concentration gradient across the membrane

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.

Water is constantly diffusing into the cytosol of freshwater single-celled organisms. In order to maintain the proper solute concentrations in the cytosol, contractile vacuoles pump out the excess water. An experimenter placed single-celled organisms into various saline concentrations and recorded the ATP used by the contractile vacuole. The data are shown in the graph.

Of the following, which additional investigation can be used to determine when the cells are in an isotonic solution?

Increasing the salinity of the environment a little at a time until the ATP usage reaches a minimum

A student peeled the skins from grapes, exposing cells with membranes that are only permeable to water and small diffusible solutes. The student measured the mass of the peeled grapes. The student then placed each peeled grape into one of five solutions. After 24 hours, the student removed the peeled grapes from the solutions, measured their final mass, and calculated the percent change in mass (Table 1).

TABLE 1. PERCENT CHANGE IN MASS OF PEELED GRAPES IN SOLUTIONS

Solution	Concentration of Solution(weight/volume)	Percent Change in Mass
Distilled water	0%	13.48%
NaCl	20%	−23.39%
Tap water	0.8%	9.46%
Grape juice	2.1%	2.8%
Grape soda	13%	−15.00%

In a second experiment (Table 2), the student placed a peeled grape into a solution containing both small diffusible solutes and solutes to which the membrane is impermeable (nondiffusible solutes).

TABLE 2. CONCENTRATION OF SOLUTES IN SECOND EXPERIMENT

Location	Concentration of Small Diffusible Solutes	Concentration of Nondiffusible Solutes
Inside grape	0.4⁢M	1.2M
In solution	1.6M	0.8M

Assuming a negligible pressure potential, which of the following best predicts the net movement of the small diffusible solutes and water in the second experiment (Table 2) ?

Small diffusible solutes will diffuse into the grape cells, followed by water.

The transport of a substance across a plasma membrane of a specific organelle requires energy. The rate at which the transport takes place also depends on temperature. A scientist isolated the specific organelle and then used the following treatments to determine the conditions that will result in the maximal transport. All treatments contained the extracted organelle and were maintained at 25°C.

The data from this experiment indicate that maximal rate of transport of protein X at 25°C occurs at an ATP concentration of 1.0�m/mL.

Figure 1. The four ATP concentrations used in the experiment

Which procedure should be done next to gather data needed to meet the scientist’s objective?

Incubate samples containing 1.0�m/mL of ATP at four temperatures other than 25°C.

Simple diffusion and facilitated diffusion are related in that both

depend on a concentration gradient

The illustration shows the active transport of hydrogen ions through a membrane protein.

Which of the following best predicts the effect of not having ATP available to supply energy to this process?

H+ ions will stop moving through the protein.

Which statement best describes the effect on water transport across the cell membrane if the aquaporin in the figure ceases to function?

Water molecules will still be able to move across the cell membrane but at a slower rate.

If ATP breakdown (hydrolysis) is inhibited, which of the following types of movement across cell membranes is also inhibited?

Passage of a solute against its concentration gradient

Which of the following components of the cell membrane is responsible for active transport?

Protein

When a substance moves across the plasma membrane along a concentration gradient at a rate faster than would be expected by simple diffusion alone but without the expenditure of metabolic energy, the process is best described as

facilitated diffusion

A student peeled the skins from grapes, exposing cells with membranes that are only permeable to water and small diffusible solutes. The student measured the mass of the peeled grapes. The student then placed each peeled grape into one of five solutions. After 24 hours, the student removed the peeled grapes from the solutions, measured their final mass, and calculated the percent change in mass (Table 1).

TABLE 1. PERCENT CHANGE IN MASS OF PEELED GRAPES IN SOLUTIONS

Solution	Concentration of Solution(weight/volume)	Percent Change in Mass
Distilled water	0%	13.48%
NaCl	20%	−23.39%
Tap water	0.8%	9.46%
Grape juice	2.1%	2.8%
Grape soda	13%	−15.00%

In a second experiment (Table 2), the student placed a peeled grape into a solution containing both small diffusible solutes and solutes to which the membrane is impermeable (nondiffusible solutes).

TABLE 2. CONCENTRATION OF SOLUTES IN SECOND EXPERIMENT

Location	Concentration of Small Diffusible Solutes	Concentration of Nondiffusible Solutes
Inside grape	0.4⁢M	1.2M
In solution	1.6M	0.8M

Mercurial sulfhydryl is an inhibitor of aquaporins. Which of the following is the most likely effect of adding mercurial sulfhydryl to the distilled water solution?

The grape cells will gain water more slowly because of a lack of facilitated diffusion.

A human kidney filters about 200 liters of blood each day. Approximately two liters of liquid and nutrient waste are excreted as urine. The remaining fluid and dissolved substances are reabsorbed and continue to circulate throughout the body. Antidiuretic hormone (ADH) is secreted in response to reduced plasma volume. ADH targets the collecting ducts in the kidney, stimulating the insertion of aquaporins into their plasma membranes and an increased reabsorption of water.

If ADH secretion is inhibited, which of the following would initially result?

The person would produce greater amounts of dilute urine.

A human kidney filters about 200 liters of blood each day. Approximately two liters of liquid and nutrient waste are excreted as urine. The remaining fluid and dissolved substances are reabsorbed and continue to circulate throughout the body. Antidiuretic hormone (ADH) is secreted in response to reduced plasma volume. ADH targets the collecting ducts in the kidney, stimulating the insertion of aquaporins into their plasma membranes and an increased reabsorption of water.

If ADH secretion is inhibited, which of the following would initially result?

The person would produce greater amounts of dilute urine.

A cell’s membrane potential is maintained by the movement of ions into and out of the cell. A model showing the influence of membrane proteins on the movement of sodium (Na+) and potassium (K+) ions across the plasma membrane is presented in Figure 1.

Figure 1. Section of a cell’s plasma membrane, showing ion concentrations and membrane proteins

 

Based on the model presented in Figure 1, which of the following outcomes will most likely result from a loss of protein X function?

The membrane potential will be disrupted by an increase in K+ concentration inside the cell.

The rate of transpiration, the flow of water through the stem, and leaf water potential are measured in a tree during a 24-hour period under normal environmental conditions. The results from these measurements are shown in the graphs below.

All of the following changes would be likely to decrease the rate of transpiration at 8 A.M. EXCEPT

increasing the water potential of the soil

• Directions: Each group of questions below concerns an experimental or laboratory situation or data. In each case, first study the description of the situation or data. Then choose the one best answer to each question following it and fill in the corresponding circle on the answer sheet.

Dialysis tubing is permeable to water molecules but not to sucrose. Four dialysis tubes are half filled with 5 percent, 10 percent, 20 percent, and 40 percent sucrose solutions, respectively, and two dialysis tubes are half filled with distilled water. The dialysis tubes are all sealed at both ends, and the initial masses are determined. Five dialysis tubes are placed into beakers containing distilled water, and the sixth dialysis tube, containing distilled water, is placed into a 40 percent sucrose solution. The masses of the dialysis tubes are recorded at 30-minute intervals for 90 minutes, as shown in the table below.

The contents of which dialysis tube are initially isotonic to the distilled water in the beaker?

5

• Directions: Each group of questions below concerns an experimental or laboratory situation or data. In each case, first study the description of the situation or data. Then choose the one best answer to each question following it and fill in the corresponding circle on the answer sheet.

Dialysis tubing is permeable to water molecules but not to sucrose. Four dialysis tubes are half filled with 5 percent, 10 percent, 20 percent, and 40 percent sucrose solutions, respectively, and two dialysis tubes are half filled with distilled water. The dialysis tubes are all sealed at both ends, and the initial masses are determined. Five dialysis tubes are placed into beakers containing distilled water, and the sixth dialysis tube, containing distilled water, is placed into a 40 percent sucrose solution. The masses of the dialysis tubes are recorded at 30-minute intervals for 90 minutes, as shown in the table below.

A net movement of water into the beaker occurs in which of the following dialysis tubes?

6

• Directions: Each group of questions below concerns an experimental or laboratory situation or data. In each case, first study the description of the situation or data. Then choose the one best answer to each question following it and fill in the corresponding circle on the answer sheet.

Dialysis tubing is permeable to water molecules but not to sucrose. Four dialysis tubes are half filled with 5 percent, 10 percent, 20 percent, and 40 percent sucrose solutions, respectively, and two dialysis tubes are half filled with distilled water. The dialysis tubes are all sealed at both ends, and the initial masses are determined. Five dialysis tubes are placed into beakers containing distilled water, and the sixth dialysis tube, containing distilled water, is placed into a 40 percent sucrose solution. The masses of the dialysis tubes are recorded at 30-minute intervals for 90 minutes, as shown in the table below.

To model a plant cell, a permeable, nonflexible case is placed around each piece of dialysis tubing. The greatest pressure potential will develop within dialysis tube number 

4

The following questions refer to an experiment in which a dialysis-tubing bag is filled with a mixture of 3% starch and 3% glucose and placed in a beaker of distilled water, as shown below. After 3 hours, glucose can be detected in the water outside the dialysis-tubing bag, but starch cannot.

From the initial conditions and results described, which of the following is a logical conclusion?

The pores of the bag are larger than the glucose molecules but smaller than the starch molecules.

The following questions refer to an experiment in which a dialysis-tubing bag is filled with a mixture of 3% starch and 3% glucose and placed in a beaker of distilled water, as shown below. After 3 hours, glucose can be detected in the water outside the dialysis-tubing bag, but starch cannot.

Which of the following best describes the condition expected after 24 hours?

The bag will contain more water than it did in the original condition.

The following questions refer to an experiment in which a dialysis-tubing bag is filled with a mixture of 3% starch and 3% glucose and placed in a beaker of distilled water, as shown below. After 3 hours, glucose can be detected in the water outside the dialysis-tubing bag, but starch cannot.

If, instead of the bag, a potato slice were placed in the beaker of distilled water, which of the following would be true of the potato slice?

It would gain mass.

A student peeled the skins from grapes, exposing cells with membranes that are only permeable to water and small diffusible solutes. The student measured the mass of the peeled grapes. The student then placed each peeled grape into one of five solutions. After 24 hours, the student removed the peeled grapes from the solutions, measured their final mass, and calculated the percent change in mass (Table 1).

TABLE 1. PERCENT CHANGE IN MASS OF PEELED GRAPES IN SOLUTIONS

Solution	Concentration of Solution(weight/volume)	Percent Change in Mass
Distilled water	0%	13.48%
NaCl	20%	−23.39%
Tap water	0.8%	9.46%
Grape juice	2.1%	2.8%
Grape soda	13%	−15.00%

In a second experiment (Table 2), the student placed a peeled grape into a solution containing both small diffusible solutes and solutes to which the membrane is impermeable (nondiffusible solutes).

TABLE 2. CONCENTRATION OF SOLUTES IN SECOND EXPERIMENT

Location	Concentration of Small Diffusible Solutes	Concentration of Nondiffusible Solutes
Inside grape	0.4⁢M	1.2M
In solution	1.6M	0.8M

Based on Table 1, which of the following best explains the difference in water potential between certain solutions and the grapes?

Grape soda and NaCl have a lower water potential because these two solutions caused the grape to lose water.

A student peeled the skins from grapes, exposing cells with membranes that are only permeable to water and small diffusible solutes. The student measured the mass of the peeled grapes. The student then placed each peeled grape into one of five solutions. After 24 hours, the student removed the peeled grapes from the solutions, measured their final mass, and calculated the percent change in mass (Table 1).

TABLE 1. PERCENT CHANGE IN MASS OF PEELED GRAPES IN SOLUTIONS

Solution	Concentration of Solution(weight/volume)	Percent Change in Mass
Distilled water	0%	13.48%
NaCl	20%	−23.39%
Tap water	0.8%	9.46%
Grape juice	2.1%	2.8%
Grape soda	13%	−15.00%

In a second experiment (Table 2), the student placed a peeled grape into a solution containing both small diffusible solutes and solutes to which the membrane is impermeable (nondiffusible solutes).

TABLE 2. CONCENTRATION OF SOLUTES IN SECOND EXPERIMENT

Location	Concentration of Small Diffusible Solutes	Concentration of Nondiffusible Solutes
Inside grape	0.4⁢M	1.2M
In solution	1.6M	0.8M

Based on Table 1, which of the following percentages is closest to the solute concentration of the grape?

5.5%

A student peeled the skins from grapes, exposing cells with membranes that are only permeable to water and small diffusible solutes. The student measured the mass of the peeled grapes. The student then placed each peeled grape into one of five solutions. After 24 hours, the student removed the peeled grapes from the solutions, measured their final mass, and calculated the percent change in mass (Table 1).

TABLE 1. PERCENT CHANGE IN MASS OF PEELED GRAPES IN SOLUTIONS

Solution	Concentration of Solution(weight/volume)	Percent Change in Mass
Distilled water	0%	13.48%
NaCl	20%	−23.39%
Tap water	0.8%	9.46%
Grape juice	2.1%	2.8%
Grape soda	13%	−15.00%

In a second experiment (Table 2), the student placed a peeled grape into a solution containing both small diffusible solutes and solutes to which the membrane is impermeable (nondiffusible solutes).

TABLE 2. CONCENTRATION OF SOLUTES IN SECOND EXPERIMENT

Location	Concentration of Small Diffusible Solutes	Concentration of Nondiffusible Solutes
Inside grape	0.4⁢M	1.2M
In solution	1.6M	0.8M

A student hypothesizes that the solute concentration of grape juice is higher than the solute concentration of the actual grape because the grape juice has added sugar.

Based on the data in Table 1, which of the following best evaluates the student’s hypothesis?

The hypothesis is not supported because the mass of the grape increased in the grape juice.

Stickleback fish are found in both marine and freshwater habitats. The marine fish have no scales but have hardened, armorlike plates along their sides. The plates are thought to protect sticklebacks from certain predators.

In the late 1980s, sticklebacks from a marine population colonized Loberg Lake, a freshwater lake in Alaska. Starting in 1990, researchers sampled fish from the lake every four years and recorded the armor-plate phenotypes of the male sticklebacks in each sample. The armor-plate phenotypes were categorized as either complete (plates extending from head to tail), partial (plates extending from head to abdomen), or low (a few plates near the head only). The results are shown in the table below.

ARMOR-PLATE VARIATION IN THE STICKLEBACK POPULATION OF LOBERG LAKE

 

Percent of Males in the Sample with Each Armor-Plate Phenotype

Year	Low	Partial	Complete
1990	1%	2%	97%
1994	45%	14%	41%
1998	58%	16%	26%
2002	76%	15%	9%
2006	90%	6%	4%

 

 

Intact cells of two unknown cell types were placed into solutions with different concentrations of NaCl. Type I cells swelled and burst in the solution with the lowest concentration of NaCl. Type II cells swelled but did not burst in the solution with the lowest concentration of NaCl.

Which of the following descriptions of cell type I and cell type II are most consistent with the data?

Cell Type I	Cell Type II
Animal cell surrounded by a plasma membrane only	Plant cell surrounded by a plasma membrane and a cell wall

Paramecia are unicellular protists that have contractile vacuoles to remove excess intracellular water. In an experimental investigation, paramecia were placed in salt solutions of increasing osmolarity. The rate at which the contractile vacuole contracted to pump out excess water was determined and plotted against osmolarity of the solutions, as shown in the graph. Which of the following is the correct explanation for the data?

The contraction rate increases as the osmolarity decreases because the amount of water entering the paramecia by osmosis increases.

Paramecia are unicellular protists that have contractile vacuoles to remove excess intracellular water. In an experimental investigation, paramecia were placed in salt solutions of increasing osmolarity. The rate at which the contractile vacuole contracted to pump out excess water was determined and plotted against osmolarity of the solutions, as shown in the graph. Which of the following is the correct explanation for the data?

The contractile vacuole is less efficient in solutions of high osmolarity because of the reduced amount of ATP produced from cellular respiration.

A student placed a semipermeable membrane inside a U-shaped channel with two chambers, as shown. The membrane permits the movement of water but not salt. The student wants to vary the rate of osmosis that occurs across the membrane. Which of the following experimental designs will result in the fastest net rate of water movement into chamber A?

Placing salt water in chamber A and distilled water in chamber B

A sample of human blood was placed in a test tube containing a physiological saline solution (0.9% sodium chloride). This type of solution is often used intravenously to quickly rehydrate patients. A drop of the blood from the test tube was placed on a slide and red blood cells (RBCs) were observed under a microscope. Three possible outcomes are diagrammed below.

Which of the following best predicts which diagrammed microscope view the laboratory worker would see and best explains why?

View 2 because the rate of water movement into the RBCs equals the rate of water movement out of the cells

A common laboratory investigation involves putting a solution of starch and glucose into a dialysis bag and suspending the bag in a beaker of water, as shown in the figure below.

 

 

 

The investigation is aimed at understanding how molecular size affects movement through a membrane.

Which of the following best represents the amount of starch, water, and glucose in the dialysis bag over the course of the investigation?

The following question refer to the graph below, which illustrates the percent change in the mass of pieces of plant tissue placed in solutions of different sucrose molarities.

Water enters and leaves the plant cells primarily by

osmosis

The rate of transpiration, the flow of water through the stem, and leaf water potential are measured in a tree during a 24-hour period under normal environmental conditions. The results from these measurements are shown in the graphs below.

What can be deduced from graph I?

The maximal flow of water through the stem lags behind the maximal rate of transpiration.

A scientist designed an experiment to test an artificial membrane that mimics the phospholipid bilayer of a cell.

The scientist built a tube that was divided by an artificial membrane and filled with distilled water. The scientist put a known amount of a protein into the water on one side of the membrane. After some time, the scientist measured the concentration of the protein on either side of the membrane but found that there had been no change.

Which of the following experimental changes would allow the scientist to observe transport of a solute across the artificial membrane?

Use a small, nonpolar solute instead of a protein

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?

The animal’s body cells are defective in endocytosis.

Which of the following scientific questions is most relevant to the model represented in the figure above?

Which molecular substance is actively transported across the plasma membrane?

Which of the following statements best explains the processes of passive and active transport?

Passive transport is the net movement of substances down a concentration gradient that does not require metabolic energy. Active transport is the movement of substances up a concentration gradient that requires energy.

In an experiment, cells were isolated from an aquatic plant and suspended in pond water, a sucrose sugar solution, or distilled water. All of the cells were then viewed under a microscope. Compared with the cell in the pond water, the cell in the sugar solution appeared shriveled, and the cell in the distilled water appeared inflated. The results of the experiment are represented in Figure 1.

Figure 1. The results of an experiment using aquatic plant cells

 

Which of the following statements best explains the observations represented in Figure 1 ?

There was a net movement of water out of the cell suspended in the sugar solution and a net movement of water into the cell suspended in the distilled water.

What evolutionary advantage does compartmentalization of core metabolic processes offer eukaryotes?

Evolution of a nucleus in eukaryotes separates the processes of transcription and translation and they can be regulated separately.

Changing the shape or morphology of the mitochondrial inner membrane can change the efficiency of mitochondrial function.

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?

Mitochondria will become less efficient because the surface area of the inner mitochondrial membranes will decrease.

The figure shows a process by which a cell might absorb food from its surrounding environment and break it down for use as a source of energy and matter. The process involves lysosomes, which are membrane-bound organelles that contain hydrolytic enzymes. Activation of the hydrolytic enzymes requires an acidic pH, and lysosomes maintain an internal acidic pH by using ion pumps.

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.

Membrane-bound organelles have been an important component in the evolution of complex, multicellular organisms. Which of the following best summarizes an advantage of eukaryotic cells having internal membranes?

Organelles isolate specific reactions, increasing metabolic efficiency.

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 reactions.

Researchers claimed that a particular organelle originated from a free-living prokaryotic cell that was engulfed by a larger cell, as shown in Figure 1.

Figure 1. A model showing a cell engulfing a smaller cell

Which of the following provides evidence to best support the researchers’ claim?

The organelle has a double membrane.

The diagram above represents a typical rod-shaped bacterium. Which of the following best describes a feature shown in the diagram that is unique to archaea and bacteria?

The organism does not have a nuclear membrane surrounding its genetic material.

The following questions refer to the following diagram. For each phrase or sentence, select the labeled part to which it is most closely related. Each option may be used once, more than once, or not at all for each group.

 

Evolved from a photoautotrophic prokaryote

B (Chloroplast)

Which of the following best supports the statement that mitochondria are descendants of endosymbiotic bacteria-like cells?

Mitochondria and bacteria possess similar ribosomes and DNA.

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 DNA that is more similar to prokaryotic DNA in structure and function than to the eukaryotic DNA found in the cell's nucleus.