ap bio
Which of the following is the best explanation for the pattern of change in mass of the organisms over time?
cellular respiration
Process found in both photosynthesis and cellular respiration
chemiosmosis (E)
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
Based on the data shown, changes in the light intensity resulted in changes in the rate of which of the following processes?
Photosynthesis
Which of the following statements best describes how organisms such as rabbits obtain the carbon necessary for building biological molecules?
Rabbits eat plants and break down plant molecules to obtain carbon and other atoms that they rearrange into new carbon-containing molecules.
Which of the following can be used to determine the rate of enzyme-catalyzed reactions?
Rate of disappearance of the substrate
If 30% of the nucleotides in a single-stranded RNA molecule are adenine, then what percent are expected to be thymine
0
Process in which sugar is oxidized to pyruvic acid
glycolysis (a)
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 smallest one (10)
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
Site of conversion of chemical energy of glucose to ATP
A
Site of modification and packaging of proteins and lipids prior to export from the cell
C
An increase in the rate of oxygen production by algae would be accompanied by a comparable increase in the rate of production of which of the following substances?
C6H12O6
Process in which carbon from CO2 is incorporated into organic molecules
Calvin Cycle (c)
Which of the following best describes the role of mitosis in the cell cycle?
Distributing replicated chromosomes to daughter nuclei
Researchers performed an experiment to determine the effect of certain genetic mutations on mitosis in tropical fruit fly embryos. They determined the percentage of cells in each of four phases of mitosis as shown in Figure 1. Which of the following patterns is shown by the data?
In mutant 3 cells, more time is spent in prophase/prometaphase than in the later stages of mitosis.
Process in which CO2, is released as a by-product of oxidation-reduction reactions
Krebs Cycle (b)
The amino acid in Figure 1 is found in a region of a polypeptide that folds away from water. Which part of the amino acid most likely contributes to the hydrophobic behavior of this region of the polypeptide?
Methyl (CH3CH3) group
DNA replication occurs
S phase
The sequences for two short fragments of DNA are shown above. Which of the following is one way in which these two segments would differ?
Segment 1 would become denatured at a lower temperature than would segment 2 because A-T base pairs have two hydrogen bonds whereas G-C base pairs have three.
Which of the following statements about glucose, galactose, and fructose is most likely true?
The carbohydrates have different properties because they have different arrangements of carbon, hydrogen, and oxygen atoms.
Figure 1 shows the amount of product produced in an enzyme-catalyzed reaction over five minutes. Which of the following best explains how the rate of the reaction changes over time?
The rate decreases because the ratio of product to substrate increases.
The carbon 'that makes up organic molecules in plants is derived directly from
carbon fixed in photosynthesis
Simple diffusion and facilitated diffusion are related in that both
depend on a concentration gradient
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 mRNA for those proteins on membrane-bound ribosomes. The hydrolytic enzymes are most likely to accumulate in which of the following cellular structures?
golgi complex
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?
in a mini circle and then floating outside the membrane
If the potato solution was boiled for 10 minutes and cooled for 10 minutes before being tested, the average time for the disks to float to the surface of the hydrogen peroxide solution would be
more than 30 seconds
Oxygen consumption can be used as a measure of metabolic rate because oxygen is
necessary for ATP synthesis by oxidative phosphorylation
A typical bag of fertilizer contains high levels of nitrogen, phosphorus, and potassium but trace amounts of magnesium and calcium. Which of the following best matches the fertilizer component with the molecule in which it will be incorporated by organisms in the area?
nitrogen will be incorporated into nucleic acids.
A culture of Spirogyra (an autotrophic alga) is maintained in a water solution containing dissolved carbon dioxide and a source of phosphates but lacking nitrogen compounds. A researcher determines the rates of synthesis of several organic compounds found in the Spirogyra before and after several weeks in the water solution. Which of the following graphs best illustrates a likely result of the experiment?
proteins and nucleic acids are the lowest on the graph
Precise regulation of specific hormone levels is required for optimal sperm production in mammals, as summarized in the figure above. Anabolic-androgenic steroids (AAS) are synthetic variants of testosterone that are sometimes abused by persons who desire to enhance their athletic performance or alter their physique. Assuming that AAS function in the same way as naturally occurring testosterone, it is most likely that long-term abuse of AAS would
reduce sperm production
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?
smallest one (10)
Which of the following best depicts the tertiary structures of the two proteins in water? The diagrams in the options are not drawn to the same scale as those in Figure 1 and Figure 2.
both clusters of proteins
What is the expected percent change in the DNADNA content of a typical eukaryotic cell as it progresses through the cell cycle from the start of the G1G1 phase to the end of the G2G2 phase?
100%
Students conducted a controlled experiment to investigate whether sawdust provides enough nutrients to support plant growth. The students separated ten nearly identical sunflower seedlings into two groups. They grew the seedlings in the first group in potting soil and the seedlings in the second group in sawdust composed mostly of cellulose. After twenty days, the students recorded observations about the seedlings in each group. The students' observations are presented in the table. The observed differences between the groups most likely resulted from differences in the ability of the seedlings to produce which of the following monomers?
1st one has HNRCO and the 2nd one has HONP look for H2N
The contents of which dialysis tube are initially isotonic to the distilled water in the beaker?
5
Which of the following best describes the formation of the bond shown in Figure 1 ?
A covalent bond is formed between a carbon atom and a nitrogen atom along with the formation of H2OH2O .
The diagram above illustrates feedback control as exerted by the hormone thyroxine. Following surgical removal of the thyroid gland, the level of TSH in the blood will increase. Which of the following best explains this increase?
A decrease in thyroxine levels means a loss of inhibition to the hypothalamus and anterior pituitary, leading to increased TSH secretion.
Cancer can result from a variety of different mutational events. Which of the following is LEAST likely to result in the initiation of a cancerous tumor?
A defect in a cell-cycle checkpoint prevents a cell from entering the S phase.
The graph above shows changes in glucagon and insulin secretions at different concentrations of blood glucose. Which of the following feedback mechanisms is best supported by the data?
A low glucose level causes the release of glucagon, which stimulates the release of more glucose from tissues, which in turn lowers the amount of glucagon being released.
The figure above shows a model of a ligand precursor being cleaved to produce an active ligand that binds to a specific receptor. Which of the following is most likely to reduce the binding of the active ligand to its receptor?
A mutation in the receptor gene that causes a substitution of a charged amino acid for a nonpolar amino acid in the ligand binding site of the receptor
In mammals, an increase in the concentration of sodium in the blood triggers the release of antidiuretic hormone (ADH) from the pituitary gland. As the concentration of sodium in the blood returns to previous levels, the release of ADH from the pituitary gland is reduced. Based on the information presented, which of the following describes the most likely role of ADH in maintaining blood osmolarity?
ADH promotes an increase in the movement of water into the bloodstream.
Which of the following best accounts for the shape of the solid line between points A and D?
ATP acted as an allosteric inhibitor on one or more of the enzymes.
The energy required to run the Calvin cycle reactions of photosynthesis comes from which two substances produced during the light-dependent reactions?
ATP and NADPH
Damaged tissue releases chemicals that activate platelets and stimulate the formation of blood clots. Which of the following predictions about the activity of platelets best describes a positive feedback mechanism?
Activated platelets release chemicals that activate more platelets.
Which of the following best explains the reactions of these enzymes?
Amylase aids in the addition of a water molecule to break covalent bonds whereas glycogen synthase aids in the removal of a water molecule to form covalent bonds.
Mitochondria are found in most eukaryotic cells and contain their own DNA and ribosomes that are similar to those typical of many prokaryotic cells. Which of the following statements is justified by these observations?
An ancestral cell most likely engulfed an aerobic prokaryote in a relationship that proved beneficial for both cells.
The vertebrate forelimb initially develops in the embryo as a solid mass of tissue. As development progresses, the solid mass near the end of the forelimb is remodeled into individual digits. Which of the following best explains the role of apoptosis in remodeling of the forelimb?
Apoptosis involves the regulated activation of proteins in specific cells of the developing forelimb that leads to the death of those cells.
Antidiuretic hormone (ADH) is important in maintaining homeostasis in mammals. ADH is released from the hypothalamus in response to high tissue osmolarity. In response to ADH, the collecting duct and distal tubule in the kidney become more permeable to water, which increases water reabsorption into the capillaries. The amount of hormone released is controlled by a negative feedback loop. Based on the model presented, which of the following statements expresses the proper relationship between osmolarity, ADH release, and urine production?
As tissue osmolarity rises, more ADH is released, causing less water to be excreted as urine.
Evolved from a photoautotrophic prokaryote
B) chloroplast
A common test for liver function involves sprinkling sulfur powder onto a sample of urine (mostly water with dissolved bodily waste). Sulfur powder sprinkled on a sample from an individual with impaired liver function will sink because the urine contains a high level of bile salts, while the sulfur powder sprinkled on normal urine samples will float. Which of the following best explains why bile salts cause the sulfur powder to sink?
Bile salts decrease the surface tension of the urine sample.
The model shown in the figure represents the role of two hormones, calcitonin and parathyroid hormone (PTH), in maintaining normal blood calcium levels in humans. If a dietary change results in an increase in blood calcium concentration above normal levels, which of the following is the most likely effect on calcium homeostasis?
Calcitonin levels will rise, thus promoting the deposit of calcium into bones.
Site of glucose synthesis
Chloroplast B
Which of the following presents a correct interpretation of the changes in chromosome number depicted in Figure 1 ?
Chromosomes enter metaphase containing two chromatids attached by a centromere. During anaphase, the chromatids are separated, each becoming a chromosome. Cytokinesis distributes the chromosomes into two separate cells.
Process in which O2 is released as a by-product of oxidation-reduction reactions
D light dependent photosynthesis
Bacteriophages are viruses that infect bacteria. In an experiment, bacteriophages were labeled with either radioactive phosphorus or radioactive sulfur. The labeled bacteriophages were incubated with bacteria for a brief amount of time and then removed. The infected bacteria cells were found to contain significant amounts of radioactive phosphorus but not radioactive sulfur. Based on the results of the experiment, which of the following types of molecules did the bacteriophages most likely inject into the bacteria cells?
DNA
To test their model, the researchers used a modified version of green fluorescent protein (GFP*) In slightly alkaline conditions, GFP exhibits a bright green fluorescence. In acidic conditions, exhibits no fluorescence. Using standard techniques, the gene encoding GFP* in laboratory-cultured nerve cells, the researchers found that a bright green fluorescence was exhibited only when a presynaptic neuron was given a certain stimulus. Based on the model, which of the following best explains how regulation of neurotransmitter release might increase the range of responses to a stimulus in the nervous system?
Different neurons in the same neural network can release different amounts of neurotransmitter.
The diagram below shows energy changes in a specific chemical reaction with and without the addition of an enzyme to the reaction. Which of the following questions can best be answered by the diagram?
Does the addition of an enzyme reduce the activation energy required for a reaction?
The maturation-promoting factor, MPF, is a cyclin-CDK complex that catalyzes the phosphorylation of other proteins to start mitosis. The activity level of MPF is dependent on the relative concentrations of the cyclin and CDK components of MPF (Figure 1). Based on Figure 1, which of the following describes the role of cyclin in the regulation of the cell cycle?
During MM phase, the cyclin level peaks, resulting in an increased binding frequency with CDK.
A scientist claims that Elysia chlorotica, a species of sea slug, is capable of photosynthesis. Which of the following observations provides the best evidence to support the claim?
Elysia chlorotica grows when exposed to light in the absence of other food sources.
Two types of cells, alpha and beta cells, produce signaling molecules that affect blood sugar levels in opposite ways (Figure 1). Epinephrine is a chemical, often released during periods of exercise, that ultimately causes an increase in blood sugar levels in the body. Based on Figure 1, which of the following best explains how exercise causes blood glucose levels to rise?
Epinephrine activates alpha cells, causing the release of glucagon, and inhibits beta cells, blocking the release of insulin.
Epinephrine is a protein hormone found in many animals. Epinephrine stimulates a signaling pathway that results in the breakdown of glycogen to glucose in the liver cells. Which of the following describes the initial steps in the process whereby epinephrine stimulates glycogen breakdown?
Epinephrine binds to a cell-surface receptor; the activated receptor stimulates production of the second messenger, cAMP
Figure 1. A model of an endocrine signaling pathway showing involved body parts and hormones GnRH = gonadotropin-releasing hormone, LH = luteinizing hormone, and FSH = follicle-stimulating hormone. Figure 1 shows a model of the endocrine signaling pathway that regulates ovulation. Which of the following observations would provide evidence of a positive feedback mechanism in this system?
Estrogen from the ovaries stimulates the hypothalamus and anterior pituitary to secrete more GnRH, LH, and FSH.
Ethylene is an organic compound produced by ripening fruits. In a controlled experiment, researchers found that ethylene gas stimulated the ripening process in newly harvested fruits. Which of the following describes the most likely connection between natural ethylene production and fruit ripening?
Ethylene gas is a chemical signal through which ripening fruits trigger the ripening process in other fruits.
Which of the following best describes the process by which gas from the atmosphere is obtained by plants and used to build lipids?
Gas is directly obtained by plants as part of the carbon cycle.
Which of the following best describes how the amount of DNADNA in the cell changes during MM phase?
The amount of DNADNA is halved as the cell divides into two daughter cells.
Which metabolic process is common to both aerobic cellular respiration and alcoholic fermentation?
Glycolysis
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
Based on Table 1, which of the following best explains the difference in water potential between certain solutions and the grapes?
Grape soda and NaClNaCl have a lower water potential because these two solutions caused the grape to lose water.
A researcher measured the temperature at which two different samples of double-stranded DNADNA denature (separate into single strands). Sample 11 denatured at a significantly lower temperature than sample 22 did. Based on the data, the researcher claims that the DNADNA in sample 22 is composed of a higher percentage of guanine and cytosine than the DNADNA in sample 11 is. Which of the following best supports the researcher's claim?
Guanine-cytosine pairs denature at a higher temperature because they have more hydrogen bonds between them than adenine-thymine pairs do.
Which of the following best explains why a cell's plasma membrane is composed of two layers of phospholipids rather than just a single layer?
Having two oppositely oriented layers of phospholipids allows only the hydrophilic heads to interact with water inside and outside of the cell.
Based on Figure 1, which of the following best describes how the properties of water at an air-water interface enable an insect to walk on the water's surface?
Hydrogen bonds between molecules at the surface of the water provide surface tension, which allows the water surface to deform but not break under the insect.
Cortisol is a hormone produced in response to stress, including starvation, in humans. Which of the following is most likely an immediate effect of a starvation-induced increase in cortisol secretion?
Increased mobilization of fatty acids from fat cells
To test their model, the researchers used a modified version of green fluorescent protein (GFP*). In slightly alkaline conditions, exhibits a bright green fluorescence. In acidic conditions, in laboratory-cultured nerve cells, the researchers found that a bright green fluorescence was exhibited only when a presynaptic neuron was given a certain stimulus. Which of the following observations best supports the hypothesis that CDK5 negatively regulates neurotransmitter release?
Inhibition of CDK5 activity in neurons increases the movement of synaptic vesicles to the plasma membrane in response to a specific stimulus.
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.
Which of the following is true of mitosis?
It maintains the same chromosome number in the daughter cells as in the parent cell.
Polypeptides are continuously being formed and degraded. One of these processes is shown. Which statement is the most accurate description of the reaction shown in Figure 1?
It represents a polypeptide chain that is broken down through a hydrolysis reaction.
The CFTRCFTR protein is made up of 1,480 amino acids linked together in a chain. Some humans produce a version of the CFTRCFTR protein in which phenylalanine (an amino acid) has been deleted from position 508 of the amino acid chain. Which of the following best predicts how the amino acid deletion will affect the structure of the CFTRCFTR protein?
It will affect the primary, secondary, and tertiary structures of the CFTRCFTR protein.
The rate of oxygen production equaled the rate of oxygen consumption during which of the following time periods?
J to K
Based on the data in Figure 1, which of the following most likely represents the change in energy that occurs when ATPATP hydrolysis is coupled with the phosphorylation of a substrate?
Line 1 represents ATPATP hydrolysis, and line 4 represents the phosphorylation of a substrate.
An intermediate electron acceptor for oxidations that occur in both glycolysis and in Krebs cycle reactions
NAD+
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.
Which of the following conclusions is most clearly supported by the representations of nucleic acid #1#1 and nucleic acid #2#2 ?
Nucleic acid #1#1 contains adenine-thymine base pairs, whereas nucleic acid #2#2 does not.
Which of the following correctly illustrates a dipeptide and an amino acid in the optimal position to form a tripeptide?
O and OH need to bond to H
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.
A researcher examining a root tip observes a plant cell with condensed sister chromatids, kinetochores with attached microtubules, and individual chromosomes that are aligned at the equatorial plate of the cell. Which of the following best describes what the next process will be in the cell?
Paired chromatids will separate, and the new daughter chromosomes will move toward opposite poles of the cell.
Based on the molecular structures shown in the figure, which molecule is likely to be solid at room temperature?
Palmitic acid, because the absence of carbon-carbon double bonds allows the molecules to pack closely together.
Most cells that have become transformed into cancer cells have which of the following characteristics when compared to normal, healthy cells?
Shorter cell cycle
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
Which of the following best describes the hydrolysis of carbohydrates?
The addition of a water molecule breaks a covalent bond between sugar monomers.
DNA and RNA are nucleic acids that can store biological information based on the sequence of their nucleotide monomers. Figure 1 shows a short segment of each of the two types of nucleic acids. Which of the following best describes a structural difference between DNA and RNA?
The backbone of DNADNA contains deoxyribose, whereas the backbone of RNARNA contains ribo
Based on the model of eukaryotic cell cycle regulation shown in the figure, which of the following best describes the effect of a drug that blocks the production of the mitotic cyclin?
The cell would be prevented from entering mitosis, and the cell would stop dividing.
Intravenous (IV) solutions administered to patients are normally isotonic. Which of the following is most likely if an IV of distilled water is administered to a patient?
The cells that are exposed to hypotonic solutions will expand as water moves osmotically into the cells from the blood.
Which of the following best describes the effect of a greater number of cysteine amino acids on the stability of the proteins?
The change leads to increased protein stability because of an increased number of S-SS-S bonds in the tertiary structure of the proteins.
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.
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
Which of the following is an accurate description of the process shown in Figure 1 ?
The formation of a covalent peptide bond in a dehydration synthesis reactio
Which of the following statements best describes how a growth factor stimulates cell division from outside a cell?
The growth factor binds to receptors on the cell surface, initiating a signal transduction pathway that activates specific target genes.
Humans produce sweat as a cooling mechanism to maintain a stable internal temperature. Which of the following best explains how the properties of water contribute to this physiological process?
The high heat of vaporization of water allows the body to remove excess heat through a phase change of water from liquid to gas.
Which of the following best describes why the disks rose to the surface faster in the more concentrated hydrogen peroxide solutions?
The higher substrate concentrations in the more concentrated solutions speeded the reaction.
Which of the following characteristics of Figure 1 best shows that the fragment is RNARNA and not DNADNA?
The identity of each nitrogenous base
The figure above shows an organelle typically found in eukaryotic cells. Which of the following best describes the function of the double membrane system of this organelle?
The inner membrane has specialized proteins that create a hydrogen ion concentration gradient between the intermembrane space and the matrix.
Which of the following best describes how amino acids affect the tertiary structure of a protein?
The interactions of the different RR-groups with other RR-groups and with their environment determine the tertiary structure of the protein.
Which of the following outcomes will most likely result from the irreversible binding of GDP to the G protein?
The intracellular concentration of glycogen will increase.
Which of the following best describes the cellular location where pyruvate dehydrogenase is most likely active?
The mitochondrial matrix
Which statement best helps explain the formation of the hydrogen bond represented in the figure?
The nitrogen has a partial negative charge, and the hydrogen attached to the oxygen has a partial positive charge.
Blood vessels are surrounded by cells called smooth muscle cells. Nitric oxide triggers a signaling cascade in smooth muscle cells that causes the cells to relax (Figure 1). Which of the following is represented by the gradual increase in thickness of the arrows from the top to the bottom of Figure 1 ?
The number of signaling molecules that are produced or activated increases with each step in the pathway.
Two nutrient solutions are maintained at the same pH. Actively respiring mitochondria are isolated and placed into each of the two solutions. Oxygen gas is bubbled into one solution. The other solution is depleted of available oxygen. Which of the following best explains why ATP production is greater in the tube with oxygen than in the tube without oxygen?
The rate of proton pumping across the inner mitochondrial membrane is lower in the sample without oxygen.
Which of the following statements best helps explain the reaction specificity of an enzyme?
The shape and charge of the substrates are compatible with the active site of the enzyme
A mutation in the gene coding for a single-polypeptide enzyme results in the substitution of the amino acid serine, which has a polar R group, by the amino acid phenylalanine, which has a nonpolar R group. When researchers test the catalysis of the normal enzyme and the mutated enzyme, they find that the mutated enzyme has much lower activity than the normal enzyme does. Which of the following most likely explains how the amino acid substitution has resulted in decreased catalytic activity by the mutated enzyme?
The substitution altered the secondary and tertiary structure of the enzyme so that the mutated enzyme folds into a different shape than the normal enzyme does.
Which of the following best describes the functionof the coenzymes NAD+ and FAD in eukaryoticcellular respiration?
They accept electrons during oxidation-reductionreactions.
Which of the following best describes the structures of carbohydrates?
They occur as monomers, chains of monomers, and branched structures.
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
One approach to treating patients with pancreatic cancer and other cancers in which the Hedgehog protein is detected is to modify the Hedgehog signaling pathway. Which of the following is the most useful approach?Treating patients with a membrane-soluble compound that can bind to Smo and block its activity
Treating patients with a membrane-soluble compound that can bind to Smo and block its activity
Ultraviolet (UVUV) radiation can damage DNADNA by breaking weak bonds. Which of the following best explains how this occurs?
UVUV radiation disrupts the double helix structure by breaking the hydrogen bonds between the nitrogenous base pairs
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
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?
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?
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 bar graph colored dark
A tissue culture of vertebrate muscle was provided with a constant excess supply of glucose under anaerobic conditions starting at time zero and the amounts of pyruvic acid and ATP produced were measured. The solid line in the graph above represents the pyruvic acid produced in moles per liter per minute. ATP levels were also found to be highest at points A and C, lowest at B and D. A second culture was set up under the same conditions, except that substance X was added, and the results are indicated by the dotted line. It is most reasonable to hypothesize that, in the breakdown of glucose, substance X is
an inhibitor
If chemical signals in the cytoplasm control the progression of a cell to the M phase of the cell cycle, then fusion of a cell in G1 with a cell in early M phase would most likely result in the
condensation of chromatin in preparation of nuclear division in both cells
The figure above shows a series of microscope images taken over time of ovalbumin production in chick oviduct cells in response to stimulation with estrogen. The ovalbumin protein was detected using a fluorescent dye as shown by the white areas in the time-lapse sequence. The microscope images indicate that ovalbumin
crosses the endoplasmic reticulum membrane as it is translated, then moves to the Golgi apparatus, then to vesicles from which it is secreted
Based on Figure 1, which of the following statements best describes the epinephrine signaling pathway?
involves enzymes activating other enzymes.
ATP serves as a common energy source for organisms because
its energy can be easily transferred to do cellular work
If the experiment is repeated at pH 11, the observed activity level of the enzyme will most likely be
lower than the level at pH 9
Contains hydrolytic enzymes associated with the intracellular digestion of macromolecules
lysomomes
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?
water is highest and glucose is lowest