AP Bio Sem1

a

A dog is following the scent of a jackrabbit. Which of the following accurately describes how the dog's brain integrates information for smell? a. Chemoreceptor cells in the nasal cavity send impulses to the appropriate area of the brain. This answer is correct. b. Chemoreceptors on epithelial cells of the tongue send hormones to the appropriate area of the brain. c. Receptors originating in the nose send action potentials to the motor regions of the brain. d. Chemoreceptors in the brain send impulses for smell in the nasal cavity.

b

Beta amylase is an enzyme that breaks down polysaccharides into component monosaccharide monomers, but is not produced by humans. Beta amylase is most effective at digesting which of the following? a. Glycogen b. CelluloseThis answer is correct. c. Starch d. Glucose

b

During the infection cycle for a typical retrovirus, such as HIV, which uses RNA as genetic material, the genetic variation in the resulting population of new virus particles is very high because of _______ (Choose all answers that apply.) a. errors in the protein molecules produced in translation b. errors introduced in the DNA molecule through reverse transcription c. recombination of the genomes of free virus particles d. damage to the virus particle from envelope loss during infection

d

Membrane-bound organelles have been an important component in the evolution of complex, multicellular organisms. Which of the following summarizes an advantage of eukaryotic cells having internal membranes? Choose all that apply. a. Eukaryotic cells are able to reproduce faster because of the presence of organelles. b. Some organelles, such as mitochondria and chloroplasts, are similar to prokaryotic cells in structure. c. Compartmentalization leads to a higher mutation rate in DNA, which leads to more new species. d. Organelles isolate specific reactions, increasing metabolic efficiency.

c, d

The last part of the metamorphosis of a tadpole to an adult frog results in the disappearance of the tail. This stage of development most likely occurs by_____________ (Choose all answers that apply.) a. bilateral division of the tail and fusion with the developing hind limbs b. individual cells of the tail migrating to the developing gonads c. apoptosis of tail cells and transfer of materials via gap junctions to cells of the appendagesThis answer is correct. d. cells of the tail dying and the nutrients being absorbed and reused by the body

b

The mechanism of action of many common medications involves interfering with the normal pathways that cells use to respond to hormone signals. Which of the following best describes a drug interaction that directly interferes with a signal transduction pathway? a. A medication causes the cell to absorb more of a particular mineral, eventually poisoning the cell. b. A medication enters the target cell and inhibits an enzyme that normally synthesizes a second messenger. c. A medication enters the target cell's nucleus and acts as a mutagen. d. A medication interrupts the transcription of ribosomal RNA genes.

c

Sickle-cell anemia results from a point mutation in the HBB gene. The mutation results in the replacement of an amino acid that has a hydrophilic R-group with an amino acid that has a hydrophobic R-group on the exterior of the hemoglobin protein. Such a mutation would most likely result in altered a. DNA structure as a result of abnormal hydrogen bonding between nitrogenous bases b. protein secondary structure as a result of abnormal hydrophobic interactions between R-groups in the backbone of the protein c. properties of the molecule as a result of abnormal interactions between adjacent hemoglobin molecules d. fatty acid structure as a result of changes in ionic interactions between adjacent fatty acid chains

b

The endocrine system incorporates feedback mechanisms that maintain homeostasis. Which of the following demonstrates negative feedback by the endocrine system? a. During labor, the fetus exerts pressure on the uterine wall, inducing the production of oxytocin, which stimulates uterine wall contraction. The contractions cause the fetus to further push on the wall, increasing the production of oxytocin. b. After a meal, blood glucose levels become elevated, stimulating beta cells of the pancreas to release insulin into the blood. Excess glucose is then converted to glycogen in the liver, reducing blood glucose levels. c. At high elevation, atmospheric oxygen is more scarce. In response to signals that oxygen is low, the brain decreases an individual's rate of respiration to compensate for the difference. d. A transcription factor binds to the regulatory region of a gene, blocking the binding of another transcription factor required for expression.

100

A typical human lymphocyte has a radius of about 10 μm, while a typical bacterium (e.g., S. pneumoniae) has a radius of about 1 μm. Assuming that both cell types are perfectly spherical, how many times larger is the surface area of a typical human lymphocyte compared to the surface area of a typical bacterium? _ / 1

d

MRSA is the acronym for methicillin-resistant Staphylococcus aureus. Many of the strains of the common bacterium are also resistant to other antibiotics in use today. The resistance is linked to a collection of genes carried on plasmids that are passed from one bacterium to another by conjugation. Suppose a newly discovered, chemically different antibiotic is used in place of methicillin. Which of the following would be a probable effect on Staphylococcus aureus antibiotic resistance? (Choose all that apply.) a. Transmission of the methicillin-resistance plasmid by conjugation would increase among the Staphylococcus aureus population as the genes would confer resistance to the new antibiotic. b. Transmission of the methicillin-resistance plasmid by conjugation would increase among the Staphylococcus aureus population due to the destruction of bacteria without the plasmid through the use of the new antibiotic. c. The gene for methicillin resistance, no longer needed, would disappear entirely from Staphylococcus aureus populations within a few generations. d. Transmission of the methicillin-resistance plasmid would gradually decrease but the plasmid would not entirely disappear from the Staphylococcus aureus population.

b

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? a. Apoptosis involves the destruction of extra cells in the developing forelimb, which provides nutrients for phagocytic cells. b. Apoptosis involves the regulated activation of proteins in specific cells of the developing forelimb that leads to the death of those cells. c. Apoptosis in the developing forelimb triggers the differentiation of cells whose fate was not already determined. d. Apoptosis replaces old cells with new ones that are less likely to contain mutations.

c

A biologist spent many years researching the rate of evolutionary change in the finch populations of a group of islands. It was determined that the average beak size (both length and mass) of finches in a certain population increased dramatically during an intense drought between 1981 and 1987. During the drought, there was a reduction in the number of plants producing thin-walled seeds. Which of the following procedures was most likely followed to determine the change in beak size? a. A few finches were trapped in 1981 and again in 1987, and their beak sizes were compared. b. The beak size in fifteen finches was measured in 1987, and the beak size in the original finches was determined by estimation. c. The beak size in a large number of finches was measured every year from 1981 to 1987.This answer is correct. d. Finches were captured and bred in 1981, and the beak size of the offspring was measured.

d

A biologist spent many years researching the rate of evolutionary change in the finch populations of a group of islands. It was determined that the average beak size (both length and mass) of finches in a certain population increased dramatically during an intense drought between 1981 and 1987. During the drought, there was a reduction in the number of plants producing thin-walled seeds. Which of the following statements might best explain the increase in average beak size in the finch population during the drought? a. Finches with bigger beaks are better able to crack thick-walled seeds and produce more surviving offspring.Finches with bigger beaks can attack and kill finches with smaller beaks. b. Finches that crack large seeds develop larger beaks over time. c. Finches with bigger beaks possess more- powerful flight muscles and are able to find more food. dd. Finches with bigger beaks are better able to crack thick-walled seeds and produce more surviving offspring.

b

A biologist spent many years researching the rate of evolutionary change in the finch populations of a group of islands. It was determined that the average beak size (both length and mass) of finches in a certain population increased dramatically during an intense drought between 1981 and 1987. During the drought, there was a reduction in the number of plants producing thin-walled seeds. The biologist discovered that from 1988 to 1993, the average beak size declined to pre-1981 levels. The reversal in beak size from 1988 to 1993 was most likely related to which of the following events? a. A loss of food supply for the finches b. The end of the droughtThis answer is correct. c. An increase in drought conditions d. An increase in predators consuming finches

d

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? a. The number of aquaporins would increase in response to the inhibition of ADH. b. The person would decrease oral water intake to compensate for the inhibition of ADH. c. Blood filtration would increase to compensate for the lack of aquaporins. d. The person would produce greater amounts of dilute urine.

a

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? a. As tissue osmolarity rises, more ADH is released, causing less water to be excreted as urine. b. As tissue osmolarity rises, less ADH is released, causing less water to be excreted as urine. c. As tissue osmolarity rises, more ADH is released, causing more water to be excreted as urine. d. As tissue osmolarity rises, less ADH is released, causing more water to be excreted as urine.

c

Beaked whales feed at various depths, but they defecate at the ocean's surface. Nitrogen-rich whale feces deposited in surface waters supply nutrients for algae that are eaten by surface- dwelling fish. Which of the following best predicts what would happen if the whale population decreased? a. The remaining whales would be forced to forage in the deepest parts of the ocean. b. The remaining whales would accumulate mutations at a faster rate. c. The surface fish populations would decline due to reduced populations of algae. d. There would be a reduction in surface nitrogen concentration, which would cause an algal bloom.

c

By discharging electric sparks into a laboratory chamber atmosphere that consisted of water vapor, hydrogen gas, methane, and ammonia, Stanley Miller obtained data that showed that a number of organic molecules, including many amino acids, could be synthesized. Miller was attempting to model early Earth conditions as understood in the 1950s. The results of Miller's experiments best support which of the following hypotheses? a. The molecules essential to life today could not have been carried to the primordial Earth by a comet or meteorite. b. The molecules essential to life today did not exist at the time Earth was first formed. c. The molecules essential to life today could have formed under early Earth conditions.This answer is correct. d. The molecules essential to life today were initially self-replicating proteins that were synthesized approximately four billion years ago.

b

By discharging electric sparks into a laboratory chamber atmosphere that consisted of water vapor, hydrogen gas, methane, and ammonia, Stanley Miller obtained data that showed that a number of organic molecules, including many amino acids, could be synthesized. Miller was attempting to model early Earth conditions as understood in the 1950s. The results of Miller's experiments best support which of the following hypotheses? a. The molecules essential to life today did not exist at the time Earth was first formed. b. The molecules essential to life today could have formed under early Earth conditions.This answer is correct. c. The molecules essential to life today were initially self-replicating proteins that were synthesized approximately four billion years ago. d. The molecules essential to life today could not have been carried to the primordial Earth by a comet or meteorite.

b

Cell communication is critical for the function of both unicellular and multicellular eukaryotes. Which of the following is likely true of cell signaling? a. Cell signaling has largely been replaced by other cell functions in higher mammals. b. Similar cell signaling pathways in diverse eukaryotes are evidence of conserved evolutionary processes. c. Cell signaling functions mainly during early developmental stages. d. Cell signaling uses the highest molecular weight molecules found in living cells.

c

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? a. Because of normal phenotypic variation, only some of the fruits in a given generation are expected to produce ethylene gas. b. The rate of ethylene gas production by ripening fruits is an indicator of the relative age of an ecosystem. c. Ethylene gas is a chemical signal through which ripening fruits trigger the ripening process in other fruits. d. As a result of metabolic inactivity, newly harvested fruits are unable to absorb ethylene gas from the atmosphere.

c

If ATP breakdown (hydrolysis) is inhibited, which of the following types of movement across cell membranes is also inhibited? a. Movement of water through aquaporins b. Facilitated diffusion of a permeable substance c. Passage of a solute against its concentration gradient d. Movement of oxygen into a cell

c

In most freshwater fish, nitrogenous waste is primarily excreted as ammonia, which is highly soluble in water and is toxic at low concentrations. In terrestrial mammals, ammonia is converted to urea before it is excreted. Urea is also highly soluble in water but is less toxic than ammonia at low concentrations. Which of the following best explains why freshwater fish do not convert ammonia to urea for excretion? a. The metabolic pathways of fish do not normally involve nitrogen consumption. b. Ammonia is concentrated in tissues, where it is stored prior to excretion. c. The dilution of ammonia by direct excretion into freshwater conserves energy. d. The nitrogen in ammonia is recycled for use in protein and nucleotide synthesis.

b

In most freshwater fish, nitrogenous waste is primarily excreted as ammonia, which is highly soluble in water and is toxic at low concentrations. In terrestrial mammals, ammonia is converted to urea before it is excreted. Urea is also highly soluble in water but is less toxic than ammonia at low concentrations. Which of the following best explains why freshwater fish do not convert ammonia to urea for excretion? a. The metabolic pathways of fish do not normally involve nitrogen consumption. b. The dilution of ammonia by direct excretion into freshwater conserves energy. c. Ammonia is concentrated in tissues, where it is stored prior to excretion. d. The nitrogen in ammonia is recycled for use in protein and nucleotide synthesis.

a

Living cells typically have biosynthetic pathways to synthesize at least some of the amino acids used in making proteins. Some strains of E. coli, a prokaryote, can synthesize the amino acid tryptophan, while other E. coli strains cannot. Similarly, some strains of the yeast S. cerevisiae, a eukaryote, can synthesize tryptophan, while other S. cerevisiae strains cannot. Which of the following describes the most likely source of genetic variation found in the tryptophan synthesis pathways of both species? a. Errors in DNA replication lead to genetic variation. b. Exchange of genetic information occurs through crossing over. c. Random assortment of chromosomes leads to genetic variation. d. Viral transmission of genetic information required to synthesize tryptophan occurs.

c

Lobe-finned fishes were present in the oceans of the world approximately 400 million years ago. The first tetrapods (vertebrates that had limbs and could move on land) date to about 365 million years ago. One hypothesis states that early tetrapods evolved from lobe-finned fishes. Which of the following is the best plan for testing the hypothesis? a. Determining the number of fins found on lobe-finned fishes from different geographical locations b. Measuring the proportion of radioisotopes found in fossils of early tetrapods c. Comparing the arrangements of bones in the fins of lobe-finned fishes and limbs of the earliest tetrapodsThis answer is correct. d. Sequencing DNA isolated from fossils of lobe-finned fishes to determine the size of the genome

b

Methicillin-resistant Staphylococcus aureus (MRSA) can be a serious threat to human health. There is evidence that S. aureus infections are common in hospitals and that MRSA have become resistant to other antibiotics besides methicillin. This suggests that the rapid evolution of resistance in the bacteria poses a serious public-health challenge. Which of the following statements explains the ability of MRSA to evade existing drug therapies? Choose all answers that apply. a. MRSA metabolize many drugs in their lysosomes and therefore evolve resistance at a high rate. b. MRSA exchange genetic material with other antibiotic-resistant bacteria, which can spread resistance in the S. aureus population. c. MRSA have very long generation times and very large population sizes. d. MRSA develop new alleles by intentionally introducing specific mutations that will give them a selective advantage over other bacteria.

d

Prairie dogs are small mammals that live in large colonies in burrows in the ground. Prairie dogs that are near their own relatives when a predator approaches are much more likely to issue a warning bark than those that are near unrelated prairie dogs. The prairie dogs that hear a warning bark are more likely to hide in their burrows than to remain above ground. However, the prairie dog that gives the warning bark is putting itself at increased risk of being identified and killed by the predator. Which of the following presents the most likely evolutionary explanation for the behaviors described? a. The failure of the individual to bark when surrounded by unrelated prairie dogs ensures survival of the individual. b. The barking prairie dog is alerting unrelated prairie dogs to the predator, so it is not giving any advantage to its own relatives. c. The barking prairie dog chooses to warn other prairie dogs, leading to more prairie dogs living above ground. d. The warning bark changes the behavior of the related prairie dogs nearby, allowing the prairie dog's family to have increased survival and reproductive success.

c

The Stanley Miller apparatus demonstrated that organic molecules could assemble spontaneously in an environment lacking free oxygen and containing water, methane, and ammonia in the presence of an abundant energy source, such as an electric discharge. The research was considered supportive of the organic soup hypothesis, which states that the primitive atmosphere provided inorganic precursors from which organic molecules could have been synthesized in the presence of an energy source. Based on subsequent research, the primordial atmosphere was determined to contain less methane and more carbon dioxide. The new data about the composition of the early atmosphere had which of the following effects on origin-of-life hypotheses? a. Miller's work was used to refute the new hypothesis about the composition of the atmosphere. b. Miller's work was discarded as not relevant to an origin-of-life hypothesis. c. A new organic soup hypothesis was proposed to account for the new data about the atmosphere. This answer is correct. d. The organic soup hypothesis was abandoned as no longer being supportable.

a, d

The bacterium Vibrio cholerae is harmless unless a lysogenic bacteriophage provides the gene coding for the cholera toxin, which converts the bacterium to the virulent form that causes cholera. Select all of the following statements that explain how the gene encoding cholera toxin becomes part of the bacterial genome? Choose all answers that apply. a. The bacteriophage uses the host cell's machinery to convert its toxin gene into mRNA, which is then translated by the host cell. b. The bacteriophage makes copies of the toxin gene and expresses the copies inside the bacteriophage. c. The bacteriophage transforms itself into a self-replicating protein that can survive inside the host cell. d. The bacteriophage inserts the toxin gene into the host cell DNA, and the gene is expressed with the rest of the host cell's genes.

d

The diagram above shows the progression of ecological events after a fire in a particular ecosystem. Based on the diagram, which of the following best explains why the oak trees are later replaced by other trees? a. Roots of shrubs proliferate in the soil of the forest and prevent the oak trees from obtaining water. b. Oak trees alter the pH of the soil, making the forest better suited for shrubs and other trees. c. Oak trees succumb to environmental pollutants more readily than do either the shrubs or the other trees. d. Eventually the other trees grow taller than the oak trees and form a dense canopy that shades the understory.

c

The endocrine system incorporates feedback mechanisms that maintain homeostasis. Which of the following demonstrates negative feedback by the endocrine system? a. At high elevation, atmospheric oxygen is more scarce. In response to signals that oxygen is low, the brain decreases an individual's rate of respiration to compensate for the difference. b. During labor, the fetus exerts pressure on the uterine wall, inducing the production of oxytocin, which stimulates uterine wall contraction. The contractions cause the fetus to further push on the wall, increasing the production of oxytocin. c. After a meal, blood glucose levels become elevated, stimulating beta cells of the pancreas to release insulin into the blood. Excess glucose is then converted to glycogen in the liver, reducing blood glucose levels. d. A transcription factor binds to the regulatory region of a gene, blocking the binding of another transcription factor required for expression.

b

The pesticide DDT was widely used in the 1940s as a method of insect control. In the late 1950s the first DDT-resistant mosquitoes were discovered, and eventually DDT-resistant mosquitoes were found globally. When DDT is used now, the development of DDT resistance in mosquito populations occurs in months rather than years. Which of the following best explains the observations concerning DDT resistance in mosquitoes? a. DDT is a chemical signal that delays normal reproductive cycles in many mosquito populations. b. Natural selection favors DDT-resistant mosquitoes that are already present in a population when DDT exposure occurs.This answer is correct. c. The proportion of DDT-resistant mosquitoes in a population remains constant due to the metabolic costs of DDT utilization. d. Competition for limited resources causes mosquitoes to migrate to geographical areas that have richer supplies of DDT.

b

Thrips are insects that feed on rose pollen. Scientists noted that the thrips population increased in the spring and decreased dramatically during the summer. The researchers hypothesized that food abundance was the limiting factor for the population. Which of the following types of data would be most useful for the scientists to collect at regular intervals on a designated test plot of rose plants? a. Amount of pollen produced by each flower (g/flower) b. Density of rose pollen produced (g/m2) c. Mean temperature (∞C) d. Amount of sunlight (hours/day)

c

To test the hypothesis that a particular plant synthesizes storage lipids by using glyceraldehyde 3-phosphate (G3P) from photosynthesis, a researcher plans to use radiolabeled precursors to track the molecules through the biosynthetic pathway. Which of the following radiolabeled precursors is most appropriate for the researcher to use? a. 35S-labeled methionine, because amino acids are incorporated into lipids during photosynthesis b. 15N-labeled N2, because atmospheric nitrogen is fixed to amino acids by photosynthesis c. 14C-labeled CO2, because atmospheric carbon is fixed to carbohydrates by photosynthesisThis answer is correct. d. 32P-labeled phosphate, because lipids are stored in plants as phospholipids

d

Water in a pond contaminated with the weed killer atrazine is suspected of inhibiting metamorphosis in northern leopard frogs. A team of scientists collected fertilized northern leopard frog eggs from a different pond that is not contaminated. Which of the following is the best experimental design to determine whether atrazine is responsible for inhibiting metamorphosis in northern leopard frogs? a. Divide the fertilized eggs into three groups and expose each group to a different concentration of atrazine. Release the eggs back into the contaminated pond and check for metamorphosis after three months. b. Allow all fertilized eggs to develop into adults. Expose one-third of the frogs to one-half of the concentration of atrazine in the contaminated pond and expose another one-third of the frogs to the same concentration of atrazine as the contaminated pond. Leave the last one-third of the frogs in water with no atrazine and note any adverse changes in the physical condition of the atrazine-treated frogs in three months. c. Place all of the fertilized eggs in a pool of pond water with the same concentration of atrazine as the contaminated pond and compare the number of frogs that reach metamorphosis to those that reach adulthood in the contaminated pond. d. Place half of the fertilized eggs in a pool of water with the same concentration of atrazine as the contaminated pond and place the other half of the fertilized eggs in a pool of water that has no atrazine. Monitor the development of the embryos through metamorphosis into adulthood.

c

When a stimulus is applied to a receptor in the skin, an action potential is propagated along a neuron to the brain, where another signal is sent back to the muscle for a response. Which of the following best describes what occurs when the action potential reaches a chemical synapse at the end of an axon? a. The action potential jumps the synapse to the next connecting dendrite. b. The action potential jumps from one axon to the next connecting axon. c. The action potential causes a release of neurotransmitters that travel across the synapse. d. The action potential travels through the synapse to the next connecting dendrite.

b

Which of the following best describes an advantage that eukaryote organisms have over prokaryote organisms? Choose all answers that apply. a. Prokaryotes lack a cell membrane and therefore are unable to control what enters or exits the cell. b. Eukaryotes have organelles that allow for compartmentalization of cellular processes, which increases the efficiency of those processes. c. Eukaryotes have mitochondria and chloroplasts that contain their own genome, which allows the cells to reproduce more rapidly. d. Eukaryotes have a nuclear envelope separating their DNA from the rest of the cell, which increases the likelihood of advantageous mutations.

d

Which of the following statements most directly supports the claim that different species of organisms use different metabolic strategies to meet their energy requirements for growth, reproduction, and homeostasis? a. Carnivores have more teeth that are specialized for ripping food while herbivores have more teeth that are specialized for grinding food. b. During cold periods pond-dwelling animals can increase the number of unsaturated fatty acids in their cell membranes while some plants make antifreeze proteins to prevent ice crystal formation in tissues. c. Bacteria lack introns while many eukaryotic genes contain many of these intervening sequences. d. Plants generally use starch molecules for storage while animals use glycogen and fats for storage.

c

Which of the following statements most directly supports the claim that different species of organisms use different metabolic strategies to meet their energy requirements for growth, reproduction, and homeostasis? a. During cold periods pond-dwelling animals can increase the number of unsaturated fatty acids in their cell membranes while some plants make antifreeze proteins to prevent ice crystal formation in tissues. b. Bacteria lack introns while many eukaryotic genes contain many of these intervening sequences. c. Plants generally use starch molecules for storage while animals use glycogen and fats for storage.This answer is correct. d. Carnivores have more teeth that are specialized for ripping food while herbivores have more teeth that are specialized for grinding food.