AP BIOLOGY FINAL EXAM

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

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

Which of the following best describes the role of

water in photosynthesis?

Water molecules donate electrons to the

electron transport chain

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

Which of the following best describes the

cellular location where pyruvate dehydrogenase

is most likely active?

The mitochondrial matrix

The maximum production rate of acetyl-CoA

under condition 1 is closest to which of the

following?

1 micromole/sec

Which of the following observations provides

the best evidence that acetyl-CoA negatively

regulates pyruvate dehydrogenase activity?

The rate of the pyruvate

dehydrogenase-catalyzed reaction is

slower in the presence of a higher

concentration of acetyl-CoA

Pyruvate dehydrogenase deficiency is a genetic

disease most commonly linked to a mutation in

the a -subunit of the mitochondrial enzyme that

causes the enzyme to cease functioning. As a

result of the mutation, affected individuals build

up dangerous amounts of lactic acid. Which of

the following best explains the buildup of lactic

acid in individuals with the mutation?

Cells undergo fermentation because

pyruvate cannot be metabolized to

proceed into the Krebs cycle

The diagram shows how water can adhere to the

xylem in the stems of plants, which contributes

to water movement in the plant. Which of the

following best explains how water is able to

move upward from the roots of a plant, through

its xylem in the stem, and out to the leaves?

Water and the xylem are both polar. Water

molecules have the ability to form

hydrogen bonds with each other and with

the walls of the xylem

Protein X activates gene expression only in cells

exposed to a specific signaling molecule. In a

study, researchers determined the intracellular

location of Protein X in cultured cells both

before and after exposing the cells to the

signaling molecule. The results of the study are

shown in the diagram

Protein X is a transcription factor

The hormone prolactin has varying effects in

many different animal species. All vertebrates

produce prolactin, which is involved in signal

transduction pathways. In mammals, prolactin

stimulates the production of milk in mammary

glands. In fish, prolactin plays an important role

in osmoregulation. In birds, prolactin is

involved in lipid metabolism.

Which of the following best explains the

presence of prolactin in various vertebrate

species?

Prolactin is a homologous hormone

because it has a common origin but

different functions in various species

Which of the following best describes the

production of DMSP by coral and coral

symbionts?

A negative feedback mechanism that

reverses the environmental change

Which of the following best describes the effect

of temperature on corals' ability to produce

DMSP as shown in Figure 1 ?

Both juvenile and adult corals produce less

DMSP at 27°C than at 32°C

Which of the following best describes the

difference between the total amount of DMSP

produced by adults compared to juveniles at the

start of the 32°C trial?

Adult corals produced 5 times more DMSP than juveniles produced.

In addition to the effect of temperature on

DMSP produced by corals and their symbionts,

which of the following relationships is also

being considered in this experiment?

Effect of additional DMSP produced by

symbionts and the corals' age

Which of the following best describes the

scientists' findings concerning the density of

symbionts presented in Figure 2 ?

The symbiont density at 32°C was

different from the density at 27°C on

days 5 and 10 of the experiment

Which of the following best explains the result

of adult corals being exposed to elevated

temperatures for extended periods?

They are able to obtain less energy from

their symbionts because the algae have

been expelled

A particular gene has two alleles, a dominant

allele A and a recessive allele a. The frequency

of allele A is 0.55. If the population is in

Hardy-Weinberg equilibrium with respect to the

gene, then what is the expected frequency of

genotype Aa ?

0.495

Based on the codon chart above, which of the

following amino acid changes is most likely

found in the mutated protein?

Glu → Val

Figure 1 shows the inheritance of a particular

genetic condition in three generations of one

family. Which of the following best explains the

observed pattern of inheritance?

The condition is passed from mothers to

offspring via a mitochondrial gene

Oncogenes are genes that can cause tumor

formation as a result of a particular mutation.

Which of the following potential therapies

would be most effective at preventing the

expression of an oncogene?

Introducing a chemical that binds to

transcription factors associated with the

oncogene's promoter

Ultraviolet (UV) radiation can damage DNA by

breaking weak bonds. Which of the following

best explains how this occurs?

UV radiation disrupts the double helix

structure by breaking the hydrogen bonds

between the nitrogenous base pairs

Based on the data in the table, which of the following lizard species are most closely related?

Species E and species D

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

In which of the following tubes did the greatest

reduction of DCPIP occur after 60 minutes?

Tube 2

Which of the following claims is best supported

by the experimental results?

Light is required for the electron transport

chain to transfer electrons

Which of the following best explains how

DCMU affected the reaction?

DCMU acts as an inhibitor to the

movement of electrons within the light

reaction of photosynthesis

Which of the following best justifies the use of

tube 2 as a control treatment?

It was a positive control for measuring the

effect of DCMU on the reaction

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

Which of the following best illustrates the flow

of information required for the synthesis of

proteins encoded in the genome of a retrovirus?

RNA-->DNA-->RNA-->Protein

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 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

The diploid number of chromosomes in the cell

of a domesticated dog is 78. Which of the

following options includes the correct number of

chromosomes in a cell after each cellular process

(G2 checkpoint, meiosis, and fertilization,

respectively)?

After G2 checkpoint: 78, After Meiosis: 39, After Fertilization: 78

Based on the data in the table, which of the following best explains the effects of rotenone on cellular

respiration?

Treated cells are not able to break down NADH because certain enzymes of the electron transport chain are inhibited

Which of the following best explains why

triploid bananas do not produce seeds?

The production of gametes is disrupted

because of unequal pairing of

homologous chromosomes during

meiosis

Which of the following best explains why the

polymerase from the species T. aquaticus is

often used for PCR ?

T. aquaticus polymerase does not denature

at high temperatures

A researcher is studying two different species.

Which of the following sets of observations

would best support the claim that the two

species have structural similarities as a result of

convergent evolution?

Genetic similarity: low, Function of structure: same, Form of structure: different

Based on the cladogram, which of the following

are the traits shared between ferns and pines?

Embryo and xylem only

The researchers performed a chi-square analysis to test their hypothesis. Assuming the researchers use a

significance level of 0.05, which of the following is closest to the critical value the researchers should use in

the chi-square analysis?

3.84

Which of the following best describes what

happened to the otter population between 1750

and 1850 ?

The population lost genetic diversity as a

result of a bottleneck effect

Based on the information provided in the

passage, which of the following best describes

the effect of harmful algal blooms on otter

populations?

They are a density-independent factor that

negatively affects the otter population

regardless of its size

As otters were removed during the hunting

years, there was a large decrease in the catches

of fish species from the eelgrass habitats. Which

of the following best explains why this decrease

happened?

Otters are a keystone species, so their

disappearance from the area resulted in

the collapse of an entire community

Climate change could affect the ecosystem of

the Elkhorn Slough in many ways. From the

information provided, which of the following

predictions about the direct, local effects of

climate change is most likely?

Ocean warming will favor population

growth of nonnative species as their

habitats shift northward

Based on the information, an increase in the sea

slug population would most likely be directly

related to which of the following?

A decrease in the crab population

Many fish species, such as fathead minnows,

release a pheromone when their skin cells are

damaged. Researchers placed pike, a predator of

fathead minnows, in a choice chamber and

released the minnow pheromone at one end of

the chamber. The researchers observed that the

pike oriented themselves toward the end of the

chamber where the pheromone was released.

Which of the following questions will best guide

a follow-up investigation about the role of

pheromones in locating prey?

How do pike determine that the fathead

minnow pheromone is present in the

water?

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 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

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

Some green sea turtle females deposit their eggs

in nests that are dug on warm, tropical beaches.

Researchers have studied the effects of

temperature on the hatching rate and the

proportion of female to male hatchlings

produced at different average nest temperatures

in Suriname (Figure 1). At temperatures below

23°C or above 33°C, the eggs do not develop.

Which of the following best describes the results

shown in Figure 1 ?

Warmer nests produce more female sea

turtles than do cooler nests

Which of the following describes a scenario that

would result in the phenotypic change shown in

the graph?

House sparrows that lay

smaller-than-average clutches of eggs

produce fewer viable offspring, while

larger-than-average clutches of eggs result

in malnourished chicks that have a higher

mortality rate

Which of the following best explains the most

likely method by which this antitumor drug

works?

Trabectedin interferes with the duplication of DNA during interphase and thus prevents cancer cells from passing the G checkpoint

Based on the data in Figure 1, which of the

following best describes the inheritance pattern

of Friedreich's ataxia?

Autosomal recessive

The probability that individual III-5 will

develop Friedreich's ataxia is closest to which of

the following?

25%

Which of the following statements best describes

the results seen in Figure 2 ?

Individuals III-2 and III-3 carry two

different alleles of the FXN gene, a

mutant allele and a wild-type allele.

Individual IV-1 inherited two copies of

the mutant allele

Which of the following best describes the most

likely effect of the formation of a triplex DNA

structure (Figure 3) on the synthesis of the

frataxin protein?

RNA polymerase is prevented from

binding to the DNA, resulting in a

decrease in frataxin mRNA transcription

Which of the following types of bonds is most

likely responsible for the unusual base pairing

shown in Figure 3 that results in the formation of

a triplex DNA structure?

Hydrogen

Which of the following values is closest to the

chi-square value the scientist calculated?

23.1

Which of the following research questions would best guide an investigation of the link between the structure

of the signaling molecules and the evolution of quorum sensing?

Did these species evolve from a common ancestor that used a similar signaling molecule?

Carbon dioxide most likely enters a cell through

which of the following processes?

Simple diffusion through the membrane

In pea seeds, yellow color (Y ) is dominant to

green color (y), and a round shape (R) is

dominant to a wrinkled shape (r). A dihybrid

cross between a true-breeding plant with yellow,

round seeds (YYRR) and a true-breeding plant

with green, wrinkled seeds (yyrr) results in an

F1 generation of plants with yellow, round

seeds. Crossing two F1 plants produces an F2

generation with approximately nine times as

many plants with yellow, round seeds as plants

with green, wrinkled seeds.

Which of the following best explains these

results?

The genes for seed color and seed shape

assort independently

Which of the following best describes the hydrolysis of carbohydrates?

The addition of a water molecule breaks a covalent bond between sugar monomers.

Which of the following best describes a characteristic of DNA that makes it useful as hereditary material?

Nucleotide bases in one strand can only be paired with specific bases in the other strand.

Based on the pedigrees in Figure 1, which of the following best explains the observed pattern of inheritance?

The trait is autosomal recessive, because the cross between individuals I-1 and I-2 produced an affected offspring.

Which of the following best describes the process by which the bacteria are breaking down the glucose to produce lactic acid?

The bacteria are breaking down sugars in the absence of oxygen.

Which of the following was the dependent variable in the researcher's experiment?

pH

To investigate bacterial metabolism, a researcher divided a population (culture) of Staphylococcus capitis bacteria into two sets of culture tubes containing glucose. The researcher added a chemical to one set of tubes and measured the pH of the cultures at 5-minute intervals as the bacteria metabolized the glucose into lactic acid. The data are shown in Table 1.

TABLE 1. AVERAGE CHANGE IN pH IN CONTROL AND TREATMENT GROUPS OVER A 40-MINUTE PERIOD

This graph shows the decreasing pH values and error bars over time for both the control and treatment cultures.

To investigate bacterial metabolism, a researcher divided a population (culture) of Staphylococcus capitis bacteria into two sets of culture tubes containing glucose. The researcher added a chemical to one set of tubes and measured the pH of the cultures at 5-minute intervals as the bacteria metabolized the glucose into lactic acid. The data are shown in Table 1.

TABLE 1. AVERAGE CHANGE IN pH IN CONTROL AND TREATMENT GROUPS OVER A 40-MINUTE PERIOD

35 minutes

To investigate bacterial metabolism, a researcher divided a population (culture) of Staphylococcus capitis bacteria into two sets of culture tubes containing glucose. The researcher added a chemical to one set of tubes and measured the pH of the cultures at 5-minute intervals as the bacteria metabolized the glucose into lactic acid. The data are shown in Table 1.

According to the data, which of the following best explains the results of the experiment?

The pH of the treatment culture was lower than the pH of the control because the chemical increased the bacterial metabolic rate

A mutation in the gene coding for a single-polypeptide enzyme results in the substitution of amino acid serine, which has a polar R group, by the amino acid phenylalanine, which has a non polar 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 activist 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.

Pitcher plants are carnivorous plants that grow in areas where the soil contains low levels of key nutrient such as nitrogen. To obtain these nutrients, most pitcher plants capture prey using traps containing a digestive fluid. The captured prey are then broken down and digested, and the pitcher plant absorbs the nutrients.

The traps of one species of pitcher plant, Nepenthes hemsleyana, do not contain digestive fluid. Instead the provide a suitable place for wooly bats (Kerivoula hardwicki) to sleep. The feces from the bat are released into the trap where nutrients in the feces are absorbed and provide the plant with the nitrogen it needs.

Which of the following best describes the relationship between the pitcher plant and the wooly bat?

The relationship is an example of mutualism because both the plant and the bat benefit.

A particular genetic disorder is associated with a single gene with two alleles. Individuals with two recessive alleles are affected. The prevalence of the disorder is 1 in 6,600.

Assuming the population is in Hardy-Weinberg equilibrium, which of the following is closest to the frequency of carriers in the general population?

0.02430

Blood vessels are surrounded by called smooth muscle cells. Nitric oxide triggers a signaling cascade in smooth muscle cells that causes the cells to relax.

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.

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 the 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)

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

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 the 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)

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

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 the 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)

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

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.

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 the 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)

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

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.

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

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

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.

Which of the following best explains how some cells of an individual proceed and secrete a specific enzyme, but other cells of the same individual do not?

The cells transcribe and translate different combinations of genes, leading to the production of different sets of proteins.

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.

Pyruvate kinase, a key enzyme in the glycolysis pathway, is inhibited by the amino acid alanine. The ability of alanine to inhibit the enzyme is not affected by increasing the concentration of substrate.

Which of the following best explains the mechanism by which alanine inhibits pyruvate kinase activity?

Alanine binds to an allosteric site of the enzyme, changing the shape of the enzyme's active site.

Different species of bumblebee compete for flower nectar in their ecosystem. While the flowers vary in the length of their petals, bumblebees vary in the length of a mouth part called a proboscis. Bumblebees demonstrate a preference for flowers that correspond to the length of the proboscis. Species with proboscises of similar length tend to occupy different areas. Species that live in the same area tend to have proboscises of different lengths.

which of the following best explains the relationship between the different bumblebee species living in the same area?

The bumblebees have undergone niche partitioning due to competition.

Researchers investigated whether time of day affects the rate at which certain mRNAs produced by plants are broken down. At either 1 hour after the start of the light period (morning) or 8 hours after the start of the light period (afternoon), the researchers treated identical plant seedlings with a compound that blocks transcription (time = 0 min). The researchers measured the percent remaining of two mRNAs, mRNA G, and mRNA H over the course of 120 minutes. The data is shown in Figure 1.

Based on the data, which of the following best describes the relationship between light and degradation of mRNA G and mRNA H?

A longer exposure to light increases the rate of mRNA G degradation but not of mRNA H degradation.

Which of the following observations would best provide the strongest evidence that two plants belong to different biological species?

They produce viable but sterile offspring.

Hormones are chemical signals that are released by cells in one part of the body that travel through the bloodstream to signal cells in another part of the body. Insulin is a hormone that is released by the pancreas that induces the uptake of glucose molecules from the bloodstream into cells. In this way, insulin lowers the overall blood glucose levels of the body. Osteoblasts and osteoclasts are two types of bone cells that play a role in regulating blood glucose levels (Figure 1).

Binding of insulin to the insulin receptor on osteoblasts activates a signaling pathway that results in osteoblasts releasing a molecule, OPG, that binds to the neighboring osteoclasts. In response, the osteoclasts release protons (H+) and create an area of lower pH outside the cell. This low pH activates osteocalcin, a protein secreted in an inactive form by osteoblasts.

The Esp gene encodes a protein that alters the structure of the insulin receptor on osteoblasts and interferes with the binding of insulin to the receptor. A researcher created a group of osteoblasts with an Esp mutation that prevented the production of a functional Esp product (mutant). The researcher then exposed the mutant strain and a normal strain that expresses Esp to glucose and compared the levels of insulin in the blood near the osteoblasts (Figure 2)

Based on the information provided, which of the following best justifies the claim that osteocalcin is a hormone?

The osteoblasts in the bone secrete osteocalcin, which causes cells in the pancreas to change their activity.

Hormones are chemical signals that are released by cells in one part of the body that travel through the bloodstream to signal cells in another part of the body. Insulin is a hormone that is released by the pancreas that induces the uptake of glucose molecules from the bloodstream into cells. In this way, insulin lowers the overall blood glucose levels of the body. Osteoblasts and osteoclasts are two types of bone cells that play a role in regulating blood glucose levels (Figure 1).

Binding of insulin to the insulin receptor on osteoblasts activates a signaling pathway that results in osteoblasts releasing a molecule, OPG, that binds to the neighboring osteoclasts. In response, the osteoclasts release protons (H+) and create an area of lower pH outside the cell. This low pH activates osteocalcin, a protein secreted in an inactive form by osteoblasts.

The Esp gene encodes a protein that alters the structure of the insulin receptor on osteoblasts and interferes with the binding of insulin to the receptor. A researcher created a group of osteoblasts with an Esp mutation that prevented the production of a functional Esp product (mutant). The researcher then exposed the mutant strain and a normal strain that expresses Esp to glucose and compared the levels of insulin in the blood near the osteoblasts (Figure 2).

Which of the following best describes the effect of insulin binding to the receptor on the osteoblast cells?

Insulin binding ultimately increases pancreatic secretion of additional insulin.

Hormones are chemical signals that are released by cells in one part of the body that travel through the bloodstream to signal cells in another part of the body. Insulin is a hormone that is released by the pancreas that induces the uptake of glucose molecules from the bloodstream into cells. In this way, insulin lowers the overall blood glucose levels of the body. Osteoblasts and osteoclasts are two types of bone cells that play a role in regulating blood glucose levels (Figure 1).

Binding of insulin to the insulin receptor on osteoblasts activates a signaling pathway that results in osteoblasts releasing a molecule, OPG, that binds to the neighboring osteoclasts. In response, the osteoclasts release protons (H+) and create an area of lower pH outside the cell. This low pH activates osteocalcin, a protein secreted in an inactive form by osteoblasts.

The Esp gene encodes a protein that alters the structure of the insulin receptor on osteoblasts and interferes with the binding of insulin to the receptor. A researcher created a group of osteoblasts with an Esp mutation that prevented the production of a functional Esp product (mutant). The researcher then exposed the mutant strain and a normal strain that expresses Esp to glucose and compared the levels of insulin in the blood near the osteoblasts (Figure 2).

Which of the following claims is most consistent with the data shown in Figure 2?

Esp expression is necessary to prevent the overproduction of insulin.

Hormones are chemical signals that are released by cells in one part of the body that travel through the bloodstream to signal cells in another part of the body. Insulin is a hormone that is released by the pancreas that induces the uptake of glucose molecules from the bloodstream into cells. In this way, insulin lowers the overall blood glucose levels of the body. Osteoblasts and osteoclasts are two types of bone cells that play a role in regulating blood glucose levels (Figure 1).

Binding of insulin to the insulin receptor on osteoblasts activates a signaling pathway that results in osteoblasts releasing a molecule, OPG, that binds to the neighboring osteoclasts. In response, the osteoclasts release protons (H+) and create an area of lower pH outside the cell. This low pH activates osteocalcin, a protein secreted in an inactive form by osteoblasts.

The Esp gene encodes a protein that alters the structure of the insulin receptor on osteoblasts and interferes with the binding of insulin to the receptor. A researcher created a group of osteoblasts with an Esp mutation that prevented the production of a functional Esp product (mutant). The researcher then exposed the mutant strain and a normal strain that expresses Esp to glucose and compared the levels of insulin in the blood near the osteoblasts.

Which of the following was a positive control in the experiment?

Normal strain

Hormones are chemical signals that are released by cells in one part of the body that travel through the bloodstream to signal cells in another part of the body. Insulin is a hormone that is released by the pancreas that induces the uptake of glucose molecules from the bloodstream into cells. In this way, insulin lowers the overall blood glucose levels of the body. Osteoblasts and osteoclasts are two types of bone cells that play a role in regulating blood glucose levels (Figure 1).

Binding of insulin to the insulin receptor on osteoblasts activates a signaling pathway that results in osteoblasts releasing a molecule, OPG, that binds to the neighboring osteoclasts. In response, the osteoclasts release protons (H+) and create an area of lower pH outside the cell. This low pH activates osteocalcin, a protein secreted in an inactive form by osteoblasts.

The Esp gene encodes a protein that alters the structure of the insulin receptor on osteoblasts and interferes with the binding of insulin to the receptor. A researcher created a group of osteoblasts with an Esp mutation that prevented the production of a functional Esp product (mutant). The researcher then exposed the mutant strain and a normal strain that expresses Esp to glucose and compared the levels of insulin in the blood near the osteoblasts.

A researcher observes that mice from the mutant strain experience low blood sugar. Which of the following best describes the feedback mechanism in the pathway (Figure 1) causing the low blood sugar in the mutant strain?

The positive feedback of insulin production

A researcher hypothesizes that, in mice, two autosomal dominant traits, trait Q and trait R, are determined by separate genes found on the same chromosome. The researcher crosses mice that are heterozygous for each trait and counts the number of offspring with each combination of phenotypes. The total number of offspring produced was 64. The researcher plans to do a chi-square analysis of the data and calculates the expected number of mice with each combination of phenotypes. which of the following is the expected number of offspring that will display both trait Q and trait R?

36

Researchers studying new viruses analyzed the genetic material found in four different virus samples to determine the percent nitrogen base composition of each virus. The data is shown in the table

Which of the following samples most likely contains a double-stranded RNA virus?

Sample 1

Goats and sheep belong to the same family but different genera. While they often live together in the same pastures, the hybrid offspring that are occasionally produced between the two species rarely survive. When such a hybrid does survive, it is usually sterile.

Which of the following best explains the mechanism that maintains reproductive isolation between goats and sheep?

The two species have a different number of chromosomes, resulting in a post zygotic barrier

Ethylene gas is an organic molecule that serves many cell signaling roles in flowering plants. Which of the following best explains how a positive feedback mechanism involving ethylene works?

Cells of ripening fruit produce ethylene, which activates the ripening response in other fruit cells

A student is investigating photosynthesis in plants. The student planted grass seeds in a tray with three sections and grew the grass under artificial lights for 14 days (Figure 1). After 14 days, the student collected all of the grass from section I and recorded its mass (Table 1). The student then placed a clear cover over section II and placed an aluminum foil cover over section III (Figure 2). The student then placed the tray back under the artificial lights for even additional days. On day 21, the student collected and measured the mass of the grass from sections II and III (Table 1).

Based on the data, which of the following is the best approximation of the rate of growth per week in section II from day 14 to day 21?

4.5 g/week

A student is investigating photosynthesis in plants. The student planted grass seeds in a tray with three sections and grew the grass under artificial lights for 14 days (Figure 1). After 14 days, the student collected all of the grass from section I and recorded its mass (Table 1). The student then placed a clear cover over section II and placed an aluminum foil cover over section III (Figure 2). The student then placed the tray back under the artificial lights for even additional days. On day 21, the student collected and measured the mass of the grass from sections II and III (Table 1).

Which of the following best explains the observed differences in mass between the grass in section I after 14 days and the grass in section III after 21 days?

Mass lost by cell respiration in section III was not replaced by photosynthesis

A student is investigating photosynthesis in plants. The student planted grass seeds in a tray with three sections and grew the grass under artificial lights for 14 days (Figure 1). After 14 days, the student collected all of the grass from section I and recorded its mass (Table 1). The student then placed a clear cover over section II and placed an aluminum foil cover over section III (Figure 2). The student then placed the tray back under the artificial lights for even additional days. On day 21, the student collected and measured the mass of the grass from sections II and III (Table 1).

Which of the following best explains the connection between energy, growth, and maintenance of an ordered system in the experiment?

Energy input from light is required for the grass to grow and maintain an ordered structure.

A student is investigating photosynthesis in plants. The student planted grass seeds in a tray with three sections and grew the grass under artificial lights for 14 days (Figure 1). After 14 days, the student collected all of the grass from section I and recorded its mass (Table 1). The student then placed a clear cover over section II and placed an aluminum foil cover over section III (Figure 2). The student then placed the tray back under the artificial lights for even additional days. On day 21, the student collected and measured the mass of the grass from sections II and III (Table 1).

Based on the data, which of the following is the most likely effect of a period of increased volcanic activity that significantly decreases the amount go sunlight reaching a particular ecosystem for several years?

There will be a decrease in the population sizes of most species and a decrease in the number of trophic levels

A student is investigating photosynthesis in plants. The student planted grass seeds in a tray with three sections and grew the grass under artificial lights for 14 days (Figure 1). After 14 days, the student collected all of the grass from section I and recorded its mass (Table 1). The student then placed a clear cover over section II and placed an aluminum foil cover over section III (Figure 2). The student then placed the tray back under the artificial lights for even additional days. On day 21, the student collected and measured the mass of the grass from sections II and III (Table 1).

Which of the following is a approximate null hypothesis for the student's experiment?

The presence of light has no effect on the mass of the grass

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 (CH2) group

A researcher observes that when two heterozygous plants with red flowers are crossed, they resulting offspring include plants with red, white, or pink flowers. The researcher proposes the null hypothesis that flower color is the result of independent assortment and incomplete dominance. The researcher calculates a chi-square value of 7.3. Assuming two degrees of freedom, which of the following is the correct interpretation of the chi-square analysis, using a p-value of 0.05?

The null hypothesis should be rejected because the critical value is less than the calculated value.