Life Science (Grades 9–12)
Subtest 1 Sample Items
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Question 1
1. Which of the following laboratory activities uses materials that are considered biohazardous?
- studying osmosis using sucrose and dialysis tubing
- comparing bacterial cells and yeast cells using purchased slides
- analyzing the effect of fish oil fertilizer on plant growth rates
- testing the effectiveness of an antibiotic on different bacterial strains
Answer to question 1
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: D. (Objective 0001) Biohazardous materials are biological materials that pose a hazard to the health of living organisms or the environment. Bacteria are considered biohazardous since they can cause infection to individuals handling them and proper precautions should be taken with their handling and disposal.
Correct Response: D. (Objective 0001) Biohazardous materials are biological materials that pose a hazard to the health of living organisms or the environment. Bacteria are considered biohazardous since they can cause infection to individuals handling them and proper precautions should be taken with their handling and disposal.
Question 2
2. A life science teacher is planning a lesson that focuses on the polar bear as an example of how human-induced global climate change affects keystone species in different environments. Which of the following would provide the most useful information for analyzing the central factor that has affected the polar bear's survival?
- National Oceanic and Atmospheric Administration data on the severity of winter storms
- U.S. Fish and Wildlife Service data on the health of Arctic fish populations
- National Aeronautics and Space Administration data on the change in the extent of Arctic sea ice over the past ten years
- Environmental Protection Agency data on seasonal fluctuations in the concentration of atmospheric carbon dioxide
Answer to question 2
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: C. (Objective 0001) In addition to its work in aeronautics and space research, the National Aeronautics and Space Administration (NASA) also researches topics in Earth science. The polar bear survives by hunting seals. Bears ambush seals at their breathing holes in the sea ice covering the Arctic Ocean. Reduction in sea ice limits the area that the bears can effectively hunt and negatively impacts the survival of the population.
Correct Response: C. (Objective 0001) In addition to its work in aeronautics and space research, the National Aeronautics and Space Administration (NASA) also researches topics in Earth science. The polar bear survives by hunting seals. Bears ambush seals at their breathing holes in the sea ice covering the Arctic Ocean. Reduction in sea ice limits the area that the bears can effectively hunt and negatively impacts the survival of the population.
Question 3
3. In a graph of the results of a laboratory investigation, which of the following errors would most likely result in a misinterpretation of the data presented?
- unidentified axis labels
- lack of a trend line
- unidentified margins of error
- lack of a title
Answer to question 3
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: A. (Objective 0001) It is essential to always include labels on the axes of graphs. Data that show an increase as x and y values increase could be showing anything from the height of a plant increasing over time to the number of offspring per gram of available nutrients. Without labels, it is unclear what those values represent.
Correct Response: A. (Objective 0001) It is essential to always include labels on the axes of graphs. Data that show an increase as x and y values increase could be showing anything from the height of a plant increasing over time to the number of offspring per gram of available nutrients. Without labels, it is unclear what those values represent.
Question 4
4. Which of the following instruments will provide the best view of the inner membrane of a mitochondrion?
- transmission electron microscope
- dissecting microscope
- scanning electron microscope
- light microscope
Answer to question 4
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: A. (Objective 0001) Mitochondria are generally smaller than 10 micrometers. While the general outline of a mitochondrion can sometimes be seen with a light microscope, internal structures will not be visible. Transmission electron microscopes (TEM) transmit a beam of electrons through an ultrathin specimen, which allows for viewing samples with a much finer level of detail than is provided by light microscopes. It is from the interaction of the electrons with the specimen that the image is formed. Using a TEM, the folds of the cristae of the mitochondrion can be viewed with good resolution.
Correct Response: A. (Objective 0001) Mitochondria are generally smaller than 10 micrometers. While the general outline of a mitochondrion can sometimes be seen with a light microscope, internal structures will not be visible. Transmission electron microscopes (TEM) transmit a beam of electrons through an ultrathin specimen, which allows for viewing samples with a much finer level of detail than is provided by light microscopes. It is from the interaction of the electrons with the specimen that the image is formed. Using a TEM, the folds of the cristae of the mitochondrion can be viewed with good resolution.
Question 5
5. In biology, computer models would be most helpful for exploring which of the following phenomena?
- the life cycles of ferns and mosses
- the evolution of analogous structures in different phyla
- the nutritional requirements of a bacterial strain
- the interactions of biotic and abiotic factors in an ecosystem
Answer to question 5
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: D. (Objective 0002) Computer models are especially helpful to biologists in the study of natural phenomena that could otherwise take decades to observe. Researchers input data into computer models for an observable time period. The computer model then can extrapolate a long-term trend from the data that were input. Additionally, computer models may be used to examine how a change in a given variable influences all of the other recorded variables in a system.
Correct Response: D. (Objective 0002) Computer models are especially helpful to biologists in the study of natural phenomena that could otherwise take decades to observe. Researchers input data into computer models for an observable time period. The computer model then can extrapolate a long-term trend from the data that were input. Additionally, computer models may be used to examine how a change in a given variable influences all of the other recorded variables in a system.
Question 6
6. The Punnett square shows the possible genotypes for a single allele gene in the offspring of a homozygous recessive parent and a heterozygous parent.
top left is upper r r top right is upper r r, bottom left is r r, bottom right is r r.
Based on the genotypes shown, what is the probability that three offspring (not triplets) from these parents all will be homozygous recessive (rr) for this gene?
-
one eighth
-
one sixth
-
one fourth
-
one half
Answer to question 6
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: A. (Objective 0002) The genotypes in the Punnett square indicate a
chance that an individual offspring will be homozygous recessive (rr) for the gene. The probability that three offspring all will be homozygous recessive can be determined by calculating the product of the probabilities of each of the three offspring being homozygous recessive,
.
Correct Response: A. (Objective 0002) The genotypes in the Punnett square indicate a one half chance that an individual offspring will be homozygous recessive (rr) for the gene. The probability that three offspring all will be homozygous recessive can be determined by calculating the product of the probabilities of each of the three offspring being homozygous recessive, one half times one half times one half equals one eighth.
Question 7
7. The following data for the mass of seven objects were collected during an experiment.
3.5 g, 6.8 g, 7.3 g, 6.9 g, 7.0 g, 7.1 g, 7.2 g
Which of the following statistical calculations should be performed to produce an average mass value that most accurately reflects the values found in the data set?
- median
- mode
- standard deviation
- mean
Answer to question 7
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: A. (Objective 0002) The median is one of several statistical measurements of the center of a data set. It is the middle value of a data set that has been arranged in increasing (or decreasing) numerical order. For data sets, such as the one above, where outliers represent values that are significantly different from the rest of the data, calculating the median will produce a value that is most representative of the data in the set.
Correct Response: A. (Objective 0002) The median is one of several statistical measurements of the center of a data set. It is the middle value of a data set that has been arranged in increasing (or decreasing) numerical order. For data sets, such as the one above, where outliers represent values that are significantly different from the rest of the data, calculating the median will produce a value that is most representative of the data in the set.
Question 8
8. The Human Genome Project was a major scientific undertaking that sequenced the genomes of a variety of organisms. The technological advance that was most responsible for the ultimate success of this project was the development of:
- electron microscopes that allow the direct observation of DNA D N A molecules.
- high-speed centrifuges capable of running at low temperatures.
- techniques for cloning individual cells and stimulating the cloned cells to divide and grow.
- computers and software programs capable of generating, storing, and analyzing massive amounts of data.
Answer to question 8
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: D. (Objective 0002) The Human Genome Project aimed to map the three billion nucleotides in a haploid reference genome. The success of the project was aided considerably by advances in computer hardware and software. Computers played a significant role in generating the sequence data and in storing the data in a form that allowed for further analysis.
Correct Response: D. (Objective 0002) The Human Genome Project aimed to map the three billion nucleotides in a haploid reference genome. The success of the project was aided considerably by advances in computer hardware and software. Computers played a significant role in generating the sequence data and in storing the data in a form that allowed for further analysis.
Question 9
9. Before students in a life science class read a new chapter in their textbook, the teacher writes three to four statements on the board related to key concepts addressed in the chapter (e.g., "Limiting factors prevent a population from increasing in size indefinitely"). The teacher gives students ten minutes to discuss the statements with a partner and try to think of evidence that would support each statement. Afterward, partners share their ideas in a whole-class discussion. These prereading activities help promote students' comprehension of the chapter primarily in which of the following ways?
- by guiding the students to adjust their reading rate to match the difficulty level of the text
- by providing the students with a strategy for distinguishing facts from opinions in the text
- by showing the students how to use visualization to construct meaning as they read the text
- by activating and building the students' background knowledge related to the text
Answer to question 9
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: D. (Objective 0003) In a scientific textbook, students are likely to encounter new concepts and unfamiliar vocabulary. By presenting key concepts from a chapter to students in advance of their reading, the teacher can introduce new vocabulary and increase student understanding, thereby aiding their reading comprehension.
Correct Response: D. (Objective 0003) In a scientific textbook, students are likely to encounter new concepts and unfamiliar vocabulary. By presenting key concepts from a chapter to students in advance of their reading, the teacher can introduce new vocabulary and increase student understanding, thereby aiding their reading comprehension.
Question 10
10. Which of the following strategies would be most effective for a life science teacher to use to scaffold students' reading comprehension of an academic text by promoting their awareness of the text's organizational structure?
- providing the students with explicit instruction in morphemic analysis skills using key words from the text
- showing the students how to use a semantic web to compare and classify content words used in the text
- encouraging the students to scan the text for unfamiliar vocabulary words prior to reading
- helping the students identify and analyze the transition words used to connect ideas in the text
Answer to question 10
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: D. (Objective 0003) Writers use various organizational text structures to help clarify the relationships between ideas in a text and to support the reader's recognition of the writer's argument or purpose. Common text structures for informational and expository texts include sequence or chronological order, comparison and contrast, and definition and example. A key element that helps signal most text structures is the use of transition words and phrases that are associated with a particular organizational structure. For example, a sequential or chronological text structure might use transitions such as first, meanwhile, and next, while a comparison/contrast text structure might use transitions such as although, on the other hand, and instead of.
Correct Response: D. (Objective 0003) Writers use various organizational text structures to help clarify the relationships between ideas in a text and to support the reader's recognition of the writer's argument or purpose. Common text structures for informational and expository texts include sequence or chronological order, comparison and contrast, and definition and example. A key element that helps signal most text structures is the use of transition words and phrases that are associated with a particular organizational structure. For example, a sequential or chronological text structure might use transitions such as first, meanwhile, and next, while a comparison/contrast text structure might use transitions such as although, on the other hand, and instead of.
Question 11
11. A life science teacher notices that many students forget or begin confusing new discipline-specific vocabulary shortly after an assessment. Which instructional strategy would be most effective in promoting the students' understanding and retention of new vocabulary that has been explicitly taught?
- teaching the students how to use independent word-learning strategies to determine the meaning of unfamiliar vocabulary
- providing the students with repeated exposure to and opportunities to use new vocabulary in context
- promoting the students' recognition of discipline-specific language structures and functions
- improving the students' word-identification skills and oral reading fluency using grade-level content-area word lists
Answer to question 11
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: B. (Objective 0003) Vocabulary knowledge and concept development are closely interrelated; discipline-specific vocabulary development involves concept learning, and concept learning supports academic vocabulary development. Vocabulary development is an incremental process; more exposures to and opportunities to use new vocabulary in conceptually meaningful contexts result in greater depth of understanding and improved retention.
Correct Response: B. (Objective 0003) Vocabulary knowledge and concept development are closely interrelated; discipline-specific vocabulary development involves concept learning, and concept learning supports academic vocabulary development. Vocabulary development is an incremental process; more exposures to and opportunities to use new vocabulary in conceptually meaningful contexts result in greater depth of understanding and improved retention.
Question 12
12. The membrane potential for a cell is determined to be −100 millivolts. What does this value indicate about the cell?
- The plasma membrane is comprised of primarily positive ions.
- The cell's external environment has a higher concentration of negative ions than the cell.
- The plasma membrane blocks positive ions from entering the cell.
- The interior of the cell has a negative charge relative to the cell's external environment.
Answer to question 12
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: D. (Objective 0004) Membrane potential is a measure of the voltage that exists across the plasma membrane of a cell. The voltage is expressed in terms of the electrical charge inside the cell relative to that outside the cell. Therefore, a membrane potential of −100 millivolts indicates that the electrical charge inside the cell is more negative than the electrical charge outside the cell.
Correct Response: D. (Objective 0004) Membrane potential is a measure of the voltage that exists across the plasma membrane of a cell. The voltage is expressed in terms of the electrical charge inside the cell relative to that outside the cell. Therefore, a membrane potential of −100 millivolts indicates that the electrical charge inside the cell is more negative than the electrical charge outside the cell.
Question 13
13. The diagram shows the initial steps in the phagocytosis of microbes by a macrophage.
Step one, microbes are engulfed by the cell. Step two, the microbes are inside the cell in a membrane-bound vesicle, question mark for the next step.
Which of the following steps occurs next in this process?
- The microbes are permanently stored in the cell within the vesicle.
- The vesicle fuses with a lysosome containing digestive enzymes.
- The microbes are transported out of the cell by exocytosis.
- The vesicle migrates to the Golgi apparatus and releases the microbes.
Answer to question 13
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: B. (Objective 0004) Once the microbes are engulfed within the macrophage cell, they need to be destroyed. Lysosomes are cell organelles that contain acid hydrolase enzymes that digest worn-out organelles, food particles, or engulfed bacteria and viruses. Lysosomes fuse with the vesicle containing the microbe, exposing the bacteria or virus to the digestive enzymes and destroying it.
Correct Response: B. (Objective 0004) Once the microbes are engulfed within the macrophage cell, they need to be destroyed. Lysosomes are cell organelles that contain acid hydrolase enzymes that digest worn-out organelles, food particles, or engulfed bacteria and viruses. Lysosomes fuse with the vesicle containing the microbe, exposing the bacteria or virus to the digestive enzymes and destroying it.
Question 14
14. On a hot, dry day in Minnesota, which of the following responses will most likely be exhibited by local plants in order to maintain homeostasis?
- C3 plants will adapt a C4 photosynthetic pathway to conserve water.
- Guard cells will close stomates to reduce the evaporation of water.
- Stem cells on the side of the plant closest to the sun will elongate.
- Root cells will produce additional root hairs to absorb more water.
Answer to question 14
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: B. (Objective 0004) Stomates are openings, surrounded by guard cells, through which carbon dioxide enters a plant, and water and oxygen exit. On a hot, dry day, it is important for a plant to conserve water to avoid dehydration; therefore, the stomates will close to avoid more water loss through evaporation. By regulating the opening and closing of the stomates, guard cells help maintain homeostasis in the plant.
Correct Response: B. (Objective 0004) Stomates are openings, surrounded by guard cells, through which carbon dioxide enters a plant, and water and oxygen exit. On a hot, dry day, it is important for a plant to conserve water to avoid dehydration; therefore, the stomates will close to avoid more water loss through evaporation. By regulating the opening and closing of the stomates, guard cells help maintain homeostasis in the plant.
Diagram For Questions 15 and 16
Use the diagram below of a generalized animal cell to answer the questions that follow.
cell with a nucleus, nucleolus, mitochondrion, golgi apparatus, lysosome, golgi vesicles, rough endoplasmic reticulum coming off the nucleus and smooth endoplasmic reticulum with no ribosomes, cytoplasm microtubules. The whole cell is surrounded by the cell membrane plasma or cytoskeleton.
Question 15
15. Which of the following is a primary function of the cytoskeleton in the animal cell shown?
- providing a template on which the cell wall is formed
- storing nutrients within the cell for later use
- transporting organelles within the cell
- importing materials through the cellular membrane
Answer to question 15
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: C. (Objective 0004) The transport of cellular materials, including organelles, is a primary function of the cytoskeleton in animal cells. In addition to its transport function, the cytoskeleton also provides structural support to cells, is involved in the movement of cells, and is thought to regulate some biochemical processes.
Correct Response: C. (Objective 0004) The transport of cellular materials, including organelles, is a primary function of the cytoskeleton in animal cells. In addition to its transport function, the cytoskeleton also provides structural support to cells, is involved in the movement of cells, and is thought to regulate some biochemical processes.
Question 16
16. When the animal cell shown is in an oxygen-rich environment, pyruvate formed during glycolysis is converted to acetyl CoA and used in the reactions of the Krebs cycle. Which of the following best describes what happens to the pyruvate formed during glycolysis when oxygen is not available to the cell?
- It is degraded in the lysosomes.
- It is converted back to glucose.
- It is stored in the mitochondrial matrix.
- It is used to continue the process of glycolysis.
Answer to question 16
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: D. (Objective 0005) When oxygen is unavailable, animal cells can produce ATP by fermentation. Fermentation is a process that couples glycolysis (which yields some ATP) with reactions that regenerate NAD+. In order to maintain the production of ATP by this process, NAD+ must continue to be available for use in glycolysis. Pyruvate or its derivatives are used to regenerate NAD+ from NADH, thereby continuing the process of glycolysis.
Correct Response: D. (Objective 0005) When oxygen is unavailable, animal cells can produce A T P by fermentation. Fermentation is a process that couples glycolysis (which yields some A T P) with reactions that regenerate N A D superscript +. In order to maintain the production of A T P by this process, N A D superscript + must continue to be available for use in glycolysis. Pyruvate or its derivatives are used to regenerate N A D+ from N A D H thereby continuing the process of glycolysis.
Question 17
17. The chemical reactions of photosynthesis are summarized in the equation shown.
6CO2 subscript 2 + 12H2 subscript 2 O + light energy → C6 subscript 6 H12 subscript 12 O6 subscript 6 + 6O2 subscript 2 + 6H2 subscript 2 O
Which of the following is the source of the oxygen (O2 subscript 2 ) produced in this reaction?
- the reduction of CO2 subscript 2
- the splitting of H2 subscript 2 O
- the degradation of glucose (C6 subscript 6 H12 subscript 12 O6 subscript 6 )
- the breakdown of chlorophyll (C55 subscript 55 H72 subscript 72 MgN4 subscript 4 O5 subscript 5 )
Answer to question 17
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: B. (Objective 0005) Photosynthesis is comprised of light-dependent and light-independent reactions. The O2 produced by photosynthesis is formed by the light-dependent reactions, specifically the splitting of H2O. During this process, electrons are removed from H2O for use in photosystem II and H+ ions and O2 is formed.
Correct Response: B. (Objective 0005) Photosynthesis is comprised of light-dependent and light-independent reactions. The O subscript 2 produced by photosynthesis is formed by the light-dependent reactions, specifically the splitting of H2O. During this process, electrons are removed from H subscript 2 O for use in photosystem II and H superscript + ions and O subscript 2 is formed.
Question 18
18. ATP synthase is an enzyme complex that spans the inner membranes of mitochondria and produces ATP during oxidative phosphorylation. In order for ATP synthase to produce ATP, which of the following substances must be transported through the enzyme complex?
- H+ superscript +
- O2 subscript 2
- NADH
- CO2 subscript 2 <
Answer to question 18
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: A. (Objective 0005) The formation of ATP by ATP synthase requires the transport of H+ ions through the enzyme complex. The H+ ions are transported from the space between the inner membranes of the mitochondria to the mitochondrial matrix. The movement of H+ ions through the membrane-spanning subunit of ATP synthase causes the rotation of the stalk and F1 subunit. This rotation leads to the formation of ATP from ADP.
Correct Response: A. (Objective 0005) The formation of A T P by A T P synthase requires the transport of H superscript + ions through the enzyme complex. The H+ ions are transported from the space between the inner membranes of the mitochondria to the mitochondrial matrix. The movement of H superscript + ions through the membrane-spanning subunit of ATP synthase causes the rotation of the stalk and F subscript 1 subunit. This rotation leads to the formation of A T P from A D P.
Question 19
19. Some green plants have as many as 100 chloroplasts in one cell. Within a chloroplast in the plant cell are many flattened sacs called thylakoids. The membranes of the thylakoids contain chlorophyll pigments, which give leaves their green color. Which of the following statements best summarizes the advantage that a plant would gain by having thylakoids contained within such a small space?
- The number of chlorophyll molecules in the thylakoids enables the plant to use a wider range of light wavelengths.
- The number of thylakoids increases the surface area available for light-dependent reactions.
- The large number of thylakoids enables the plant to store more light energy within them for later use.
- The increased numbers of chlorophyll molecules in the thylakoids make the breakdown of sugar more efficient.
Answer to question 19
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: B. (Objective 0005) The function of chlorophyll in photosynthesis is to absorb light energy, which will ultimately be used to synthesize sugars for the plant. Chlorophyll is located in the thylakoids, therefore, the thylakoids are necessary for light-dependent reactions to occur. Having multiple stacks of thylakoids available provides a lot of surface area upon which the chemical reactions of the light-dependent reaction can take place.
Correct Response: B. (Objective 0005) The function of chlorophyll in photosynthesis is to absorb light energy, which will ultimately be used to synthesize sugars for the plant. Chlorophyll is located in the thylakoids, therefore, the thylakoids are necessary for light-dependent reactions to occur. Having multiple stacks of thylakoids available provides a lot of surface area upon which the chemical reactions of the light-dependent reaction can take place.
Question 20
20. In a protein molecule, interactions between the molecule's side chains are responsible for the protein's:
- primary structure.
- secondary structure.
- tertiary structure.
- quaternary structure.
Answer to question 20
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: C. (Objective 0006) All proteins are polypeptides, which are linked amino acid chains. Each amino acid is composed of a central carbon, a hydrogen, an amino group, a carboxyl group, and a variable group. When polypeptide chains fold onto themselves, parts of the amino acids come close enough to other amino acid parts that they can interact. For example, hydrogen bonds or disulfide bridges may form. These interactions help hold the protein in a specific shape, the tertiary structure.
Correct Response: C. (Objective 0006) All proteins are polypeptides, which are linked amino acid chains. Each amino acid is composed of a central carbon, a hydrogen, an amino group, a carboxyl group, and a variable group. When polypeptide chains fold onto themselves, parts of the amino acids come close enough to other amino acid parts that they can interact. For example, hydrogen bonds or disulfide bridges may form. These interactions help hold the protein in a specific shape, the tertiary structure.
Question 21
21. Which of the following characteristics is required for a protein to exhibit quaternary structure?
- a long amino acid sequence
- the close proximity of two disulfide bridges
- multiple acidic side chain groups
- the presence of more than one polypeptide
Answer to question 21
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: D. (Objective 0006) There are four levels of protein structure: primary, secondary, tertiary, and quaternary. Quaternary structure is present in a protein when two or more distinct polypeptides interact to form one functional protein.
Correct Response: D. (Objective 0006) There are four levels of protein structure: primary, secondary, tertiary, and quaternary. Quaternary structure is present in a protein when two or more distinct polypeptides interact to form one functional protein.
Question 22
22. The diagram shows a segment of double-stranded DNA.
top strand shows five prime dash t a g c a g dash three prime. bottom strand shows three prime dash a t c g t c dash five prime.
Which of the following RNA transcripts is most likely to be produced when the segment of DNA shown in the bottom strand is transcribed?
- CTGCTA
- UAGCAG
- GACGAT
- AUCGUC
Answer to question 22
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: B. (Objective 0006) RNA polymerase synthesizes RNA transcripts in a 5′ to 3′ direction by moving along the DNA template strand in a 3′ to 5′ direction. As RNA polymerase moves along the template, it matches DNA nucleotides with their complementary RNA nucleotides and adds them to the growing RNA transcript. The base-pairing rules between DNA and RNA nucleotides are as follows: adenine pairs with uracil, thymine pairs with adenine, cytosine pairs with guanine, and guanine pairs with cytosine.
Correct Response: B. (Objective 0006) R N A polymerase synthesizes R N A transcripts in a 5 prime to 3 prime direction by moving along the D N A template strand in a 3 prime to 5 prime direction. As R N A polymerase moves along the template, it matches D N A nucleotides with their complementary R N A nucleotides and adds them to the growing R N A transcript. The base-pairing rules between D N A and R N A nucleotides are as follows: adenine pairs with uracil, thymine pairs with adenine, cytosine pairs with guanine, and guanine pairs with cytosine.
Question 23
23. Regulatory molecules inhibit the activity of an enzyme through allosteric regulation by:
- binding to the active site on the enzyme.
- forming a complex with the substrate.
- changing the shape of the enzyme.
- splitting the enzyme into small subunits.
Answer to question 23
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: C. (Objective 0006) Allosteric regulation of enzyme activity can be positive or inhibitory and the mechanism involved in producing these effects is the same. In allosteric regulation, a regulatory molecule binds to a regulatory site on the enzyme that is not the active site for the substrate. This binding of the regulatory molecule induces a conformational change in the enzyme that either activates the enzyme or inhibits its activity.
Correct Response: C. (Objective 0006) Allosteric regulation of enzyme activity can be positive or inhibitory and the mechanism involved in producing these effects is the same. In allosteric regulation, a regulatory molecule binds to a regulatory site on the enzyme that is not the active site for the substrate. This binding of the regulatory molecule induces a conformational change in the enzyme that either activates the enzyme or inhibits its activity.
Question 24
24. One of the ways in which the growth of cancer cells is distinguished from the growth of normal cells is that cancer cells can:
- reproduce only if they are attached to another surface.
- divide indefinitely if supplied with adequate nutrients.
- survive only at temperatures greater than 37°C degrees celcius.
- divide without duplicating the DNA in the nucleus.
Answer to question 24
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: B. (Objective 0007) Cancer cells do not respond to the normal controls regulating the growth and division of mammalian cells. Whereas cell division in normal cells repeats only 20 to 50 times before the cells stop dividing and die, cancer cells can go on dividing indefinitely if supplied with adequate nutrients.
Correct Response: B. (Objective 0007) Cancer cells do not respond to the normal controls regulating the growth and division of mammalian cells. Whereas cell division in normal cells repeats only 20 to 50 times before the cells stop dividing and die, cancer cells can go on dividing indefinitely if supplied with adequate nutrients.
Question 25
25. Individual chromosomes of eukaryotic cells are visible with a light microscope only during certain stages of the cell cycle. Which of the following events causes the individual chromosomes to become visible?
- the attachment of proteins to the chromatids
- the duplication of each chromosome
- the condensing of chromatin fibers
- the migration of chromosomes to the cell center
Answer to question 25
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: C. . (Objective 0007) During most of the cell cycle, including S phase, chromosomes are not visible with a light microscope. It isn't until prophase, when the chromatin fibers begin to condense into tightly compacted coils, that they can be seen using a light microscope.
Correct Response: C. . (Objective 0007) During most of the cell cycle, including S phase, chromosomes are not visible with a light microscope. It isn't until prophase, when the chromatin fibers begin to condense into tightly compacted coils, that they can be seen using a light microscope.
Question 26
26. Which of the following events in meiosis is a source of the genetic variability present in gametes
- the separation of sister chromatids
- the formation of haploid daughter cells
- the movement of centrosomes within the cell
- the independent assortment of chromosomes
Answer to question 26
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: D. (Objective 0007) During meiosis I, the arrangement of replicated chromosome pairs along either side of the metaphase plate is random. In other words, the replicated chromosome pairs on one side of the metaphase plate will most likely be a combination of chromosomes from both the mother and the father. As the cell divides and continues through meiosis II, this independent assortment of chromosomes contributes to greater genetic variability in the haploid daughter cells.
Correct Response: D. (Objective 0007) During meiosis I, the arrangement of replicated chromosome pairs along either side of the metaphase plate is random. In other words, the replicated chromosome pairs on one side of the metaphase plate will most likely be a combination of chromosomes from both the mother and the father. As the cell divides and continues through meiosis II, this independent assortment of chromosomes contributes to greater genetic variability in the haploid daughter cells.
Question 27
27. A linear strand of DNA is associated with histone proteins and enclosed in a nucleus. Based on these characteristics, this structure is best described as a:
- virus.
- eukaryotic chromosome.
- prion.
- prokaryotic chromosome.
Answer to question 27
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: B. (Objective 0007) Cells that contain membrane-bound nuclei are termed eukaryotic. Chromosomes are the structures that hold the genetic information of the organism in molecules of DNA. In eukaryotic cells, the DNA is linear and coiled around histone proteins, forming nucleosomes.
Correct Response: B. (Objective 0007) Cells that contain membrane-bound nuclei are termed eukaryotic. Chromosomes are the structures that hold the genetic information of the organism in molecules of D N A. In eukaryotic cells, the DNA is linear and coiled around histone proteins, forming nucleosomes.
Question 28
28. The pedigree shows that one offspring has an autosomal recessive disease caused by a single allele, while three offspring do not.
Mother is on the left as a circle, father on the right as a square. combined to create combined lines starting at the left circle with r r inside, then square with r upper R, then circle with upper R r, then finally square with upper r upper r.
What does this pedigree indicate about the parents of these offspring?
- Both parents have the disease.
- One parent has the disease and the other does not have the disease and is not a carrier.
- Both parents are carriers of the disease
- One parent is a carrier of the disease and the other parent does not have the disease and is not a carrier.
Answer to question 28
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: C. (Objective 0008) In order for an offspring to have the disease phenotype it must have two recessive alleles for this gene (rr), one inherited from each parent. The genotypes of the other three offspring indicate that each parent also has a normal allele for this gene. This means each parent has one recessive allele for this gene and one normal allele for this gene, making them both carriers of the disease who display a disease-free phenotype.
Correct Response: C. (Objective 0008) In order for an offspring to have the disease phenotype it must have two recessive alleles for this gene (r r), one inherited from each parent. The genotypes of the other three offspring indicate that each parent also has a normal allele for this gene. This means each parent has one recessive allele for this gene and one normal allele for this gene, making them both carriers of the disease who display a disease-free phenotype.
Question 29
29. A geneticist is crossing a population of fruit flies that has an unusual eye color with a population that has normal eye color. Which of the following would provide the strongest evidence to support a conclusion that the unusual eye color is a recessive X-linked trait?
- Males in the F1 subscript 1 generation are much more likely to have the unusual eye color than females.
- Males in the F1 subscript 1 generation who have the unusual eye color produce only males with the unusual eye color in the F2 subscript 2 generation.
- All males and females in the F1 subscript 1 generation display the unusual eye color.
- Females in the F1 subscript 1 generation who have the unusual eye color produce only normal females in the F2 subscript 2 generation.
Answer to question 29
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: A. (Objective 0008) If a recessive trait is X-linked, it will be expressed more often in male offspring than in female offspring. This pattern of expression is due to the single X chromosome present in male genomes. If the recessive allele is present on the X chromosome of male offspring, it will be expressed. In contrast, since female offspring possess two X chromosomes, they will not express the trait unless they inherit recessive alleles from both parents.
Correct Response: A. (Objective 0008) If a recessive trait is X-linked, it will be expressed more often in male offspring than in female offspring. This pattern of expression is due to the single X chromosome present in male genomes. If the recessive allele is present on the X chromosome of male offspring, it will be expressed. In contrast, since female offspring possess two X chromosomes, they will not express the trait unless they inherit recessive alleles from both parents.
Question 30
30. A particular variety of flowering plant has three possible phenotypes: red flowers (RRupper R, upper R), white flowers (rrr, r), or pink flowers (Rrupper R, r). The results of a cross between a red-flowered plant and a white-flowered plant are shown in the Punnett square. If plants from the F1 subscript 1 generation are crossed, what percentage of flowers in the F2 subscript 2 generation will have pink flowers?
top left is upper R r, top right is upper R r, bottom left is upper R r, bottom right is upper R r.
- 25%
- 50%
- 75%
- 100%
Answer to question 30
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: B. (Objective 0008) As indicated in the Punnett square, all the plants in the F1 generation have the genotype for pink flowers. When these F1 pink-flowered plants are crossed, 25% of the offspring will have red flowers, 25% will have white flowers, and 50% will have pink flowers.
Correct Response: B. (Objective 0008) As indicated in the Punnett square, all the plants in the F1 generation have the genotype for pink flowers. When these F subscript 1 pink-flowered plants are crossed, 25% of the offspring will have red flowers, 25% will have white flowers, and 50% will have pink flowers.
Question 31
31. A researcher who breeds and studies a certain type of beetle predicts that all of the phenotypic traits that the beetles show are due to Mendelian inheritance. However, the researcher finds that in one generation, a new and distinctive pattern of dots appears on several male exoskeletons but does not appear on any female exoskeletons. The researcher would like to determine if this result is statistically significant. Which of the following tools would best help the researcher determine statistical significance for this study?
- t-test
- ANOVA
- Chi-square
- linear regression
Answer to question 31
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: C. (Objective 0008) A Chi-square test is a statistical tool used to analyze data that are organized into two distinct categorical variables. In this case, the categories would be the sex of the beetle and the presence of the new pattern of dots. The Chi-square test determines whether these categories are independent of one another. If the null hypothesis is supported, then the categories are independent and do not influence one another. The support or rejection of the null hypothesis is based on the p-value that the Chi-square test calculates. The p-value is the probability that the observed data are distributed as they are due to chance. By scientific consensus, the null hypothesis is rejected if the p-value is less than 0.05. If the null hypothesis is rejected, then the distribution of the data is explained by something other than chance. In this case, if this Chi-square test showed a p-value less than 0.05, then the data would show that the new exoskeleton dot pattern is in some way related to the sex of the beetle.
Correct Response: C. (Objective 0008) A Chi-square test is a statistical tool used to analyze data that are organized into two distinct categorical variables. In this case, the categories would be the sex of the beetle and the presence of the new pattern of dots. The Chi-square test determines whether these categories are independent of one another. If the null hypothesis is supported, then the categories are independent and do not influence one another. The support or rejection of the null hypothesis is based on the p-value that the Chi-square test calculates. The p-value is the probability that the observed data are distributed as they are due to chance. By scientific consensus, the null hypothesis is rejected if the p-value is less than 0.05. If the null hypothesis is rejected, then the distribution of the data is explained by something other than chance. In this case, if this Chi-square test showed a p-value less than 0.05, then the data would show that the new exoskeleton dot pattern is in some way related to the sex of the beetle.
Question 32
32. Which of the following types of mutations is depicted in the diagram below?
3' A T G G T C A T G C C T A G T 5' |
5' T A C C A G T A T G G A T C A 3' |
A diagram consists of two rows of capital letters, one row above the other. To the left of the upper row of letters is the number three followed by an apostrophe, and to the right of the upper row is the number five followed by an apostrophe. To the left of the lower row of letters is the number five followed by an apostrophe, and to the right of the lower row is the number three followed by an apostrophe. The rows of letters are aligned, with each letter in the upper row paired with a letter in the lower row. A Tee in either row is always paired with an A in the other row, and a See in one row is always paired with a Gee in the other row. There is one exception, however, where a Gee in the upper row is paired with a Tee in the lower row.
- aneuploidy
- missense mutation
- gene deletion
- frameshift mutation
Answer to question 32
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: B. (Objective 0009) A mutation is a change in a genetic sequence. In the example above, a guanine nucleotide has been substituted for an adenine nucleotide, in a missense mutation. In this type of mutation, an incorrect amino acid will be added to the growing polypeptide, possibly producing a damaged or incorrectly functioning protein.
Correct Response: B. (Objective 0009) A mutation is a change in a genetic sequence. In the example above, a guanine nucleotide has been substituted for an adenine nucleotide, in a missense mutation. In this type of mutation, an incorrect amino acid will be added to the growing polypeptide, possibly producing a damaged or incorrectly functioning protein.
Question 33
33. Which of the following plays a significant role in regulating gene expression in a eukaryotic cell?
- chemical modification of histones in chromatin
- length of the telomeres at the end of the chromosomes
- high levels of guanine in a gene sequence
- the availability of DNA polymerase in the nucleus
Answer to question 33
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: A. (Objective 0009) Genes are expressed through the processes of transcription and translation. For these processes to occur, the compact structure of chromatin must first be altered to reveal the gene sequence. The addition of certain chemical groups to histones, which reduces the attraction between the histones and the DNA, has been shown to play a significant role in this process.
Correct Response: A. (Objective 0009) Genes are expressed through the processes of transcription and translation. For these processes to occur, the compact structure of chromatin must first be altered to reveal the gene sequence. The addition of certain chemical groups to histones, which reduces the attraction between the histones and the DNA, has been shown to play a significant role in this process.
Question 34
34. The insertion of guanine between adenine (A) and cytosine (C) in positions 1 and 2 of the DNA sequence below will lead to which of the following types of mutations?
3′–ACGTTAGCGCCTATC–5′
3 prime dash a c g t t a g c g c c t a t c dash 5 prime
- missense
- neutral
- frameshift
- inversion
Answer to question 34
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: C. (Objective 0009) The insertion of guanine into the DNA sequence will change the mRNA transcript that is produced in transcription. This altered mRNA transcript will contain triplet codons that specify a different set of amino acids than originally intended. This type of mutation, in which the mRNA reading frame has been shifted by the insertion or deletion of a nucleotide, is known as a frameshift mutation.
Correct Response: C. (Objective 0009) The insertion of guanine into the DNA sequence will change the mRNA transcript that is produced in transcription. This altered mRNA transcript will contain triplet codons that specify a different set of amino acids than originally intended. This type of mutation, in which the mRNA reading frame has been shifted by the insertion or deletion of a nucleotide, is known as a frameshift mutation.
Question 35
35. Which of the following terms refers to the smallest unit?
- chromosome
- DNA
- nucleotide
- gene
Answer to question 35
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: C. (Objective 0009) The terms chromosome, DNA, nucleotide, and gene are all important in the study of genetics. Genetic information is stored in DNA molecules, which are composed of building blocks called nucleotides. A gene is a portion of a DNA molecule that codes for a protein or RNA molecule. A chromosome is composed of one DNA molecule. Therefore, the order of these terms from smallest to largest unit is: nucleotide – gene – chromosome.
Correct Response: C. (Objective 0009) The terms chromosome, DNA, nucleotide, and gene are all important in the study of genetics. Genetic information is stored in DNA molecules, which are composed of building blocks called nucleotides. A gene is a portion of a DNA molecule that codes for a protein or RNA molecule. A chromosome is composed of one DNA molecule. Therefore, the order of these terms from smallest to largest unit is: nucleotide endash gene endash chromosome.
Question 36
36. Most of the body fur of the Himalayan rabbit is white, although the fur on its feet and ears is black. In an experiment, some white fur on a Himalayan rabbit's back was clipped off, then the shaven area was cooled with an ice pack. Fur that grew back in this area was black. Which of the following statements best explains this occurrence?
- Changes in the environment can influence gene expression.
- Cold temperatures cause a mutation in the gene for fur color.
- Warm temperatures are necessary for white fur to emerge.
- The rabbit evolves darker fur in order to absorb more heat.
Answer to question 36
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: A. (Objective 0009) An organism's genotype refers to its entire set of genes, while its phenotype refers to how these genes are expressed. Not all alleles that an organism possesses are expressed in its phenotype. Moreover, the expression of a gene can be influenced by environmental changes and conditions. In the case of the Himalayan rabbit, lower temperatures affected the expression of the allele for fur color. However, the genotype of the rabbit remains unchanged.
Correct Response: A. (Objective 0009) An organism's genotype refers to its entire set of genes, while its phenotype refers to how these genes are expressed. Not all alleles that an organism possesses are expressed in its phenotype. Moreover, the expression of a gene can be influenced by environmental changes and conditions. In the case of the Himalayan rabbit, lower temperatures affected the expression of the allele for fur color. However, the genotype of the rabbit remains unchanged.
Question 37
37. In the process of cloning a human gene, the cloning vector is typically:
- a strand of bacterial RNA.
- an E. coli cell.
- an isolated bacterial plasmid.
- a nucleic acid probe.
Answer to question 37
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: C. (Objective 0010) When genes are cloned, the gene of interest is taken from its original host and placed into a cloning vector. The cloning vector is a small piece of DNA into which the foreign gene of interest can be placed. The cloning vector also needs to be stable and able to replicate easily. Plasmids make ideal cloning vectors because they are small, stable circular pieces of DNA found in bacteria. Plasmids are replicated as bacteria replicate. Bacteria replicate rapidly, producing many copies of the gene of interest; this can allow for that gene to be used elsewhere.
Correct Response: C. (Objective 0010) When genes are cloned, the gene of interest is taken from its original host and placed into a cloning vector. The cloning vector is a small piece of DNA into which the foreign gene of interest can be placed. The cloning vector also needs to be stable and able to replicate easily. Plasmids make ideal cloning vectors because they are small, stable circular pieces of DNA found in bacteria. Plasmids are replicated as bacteria replicate. Bacteria replicate rapidly, producing many copies of the gene of interest; this can allow for that gene to be used elsewhere.
Question 38
38. The illustration shows steps in the process for cloning a human protein in bacteria.
Step one, human gene with a circle labeled plasmid with a section extended from the circle around the diameter where you introduce plasmid with human gene bacteria. Step two shows a petri dish with Select for bacteria containing plasmid with the human gene. Step three shows a fermentation tank which produces large quantities of the selected bacteria. Step four shows a few squiggly lines where you isoloate and purify the desired human protein.
In Step 2 of the process, which of the following methods could be used to identify bacteria containing the human gene?
- screening for antibiotic resistance
- selecting colonies that survive at 37°C
- screening for the presence of uracil
- selecting the largest-sized colonies
Answer to question 38
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: A. (Objective 0010) Bacteria that contain the bioengineered plasmid can be readily identified if genes for resistance to specific antibiotics have been added to the plasmid. Bacteria that contain the bioengineered plasmid will grow in the presence of these antibiotics, whereas non-transformed bacteria will not. These bacteria containing the bioengineered plasmid can then be used to continue the cloning process.
Correct Response: A. (Objective 0010) Bacteria that contain the bioengineered plasmid can be readily identified if genes for resistance to specific antibiotics have been added to the plasmid. Bacteria that contain the bioengineered plasmid will grow in the presence of these antibiotics, whereas non-transformed bacteria will not. These bacteria containing the bioengineered plasmid can then be used to continue the cloning process.
Question 39
39. Golden rice is a variety of rice that has been bioengineered to produce large quantities of beta carotene. This plant was developed in order to:
- market golden rice as a better tasting and visually attractive alternative to white or brown rice.
- enable the plant to enter into a symbiotic relationship with nitrogen-fixing bacteria.
- help reduce blindness caused by vitamin A deficiency in developing countries.
- respond to the spread of a new fungus that threatened to decimate traditional strains of rice.
Answer to question 39
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: C. (Objective 0010) Golden rice contains large quantities of beta carotene, a provitamin that is converted to vitamin A in the body. Blindness caused by a deficiency of vitamin A is common in some areas of the world. Scientists hope to increase vitamin A intake and reduce blindness by substituting golden rice for white rice in the diets of susceptible populations.
Correct Response: C. (Objective 0010) Golden rice contains large quantities of beta carotene, a provitamin that is converted to vitamin A in the body. Blindness caused by a deficiency of vitamin A is common in some areas of the world. Scientists hope to increase vitamin A intake and reduce blindness by substituting golden rice for white rice in the diets of susceptible populations.
Question 40
40. Hemophilia is a genetic illness in which patients bleed excessively because they lack a particular protein, clotting factor VIII roman numeral 8 . Through genetic engineering, the human gene for clotting factor VIII roman numeral 8 can be inserted into hamster cells. This allows for the rapid production of the protein while also reducing the risk of transmitting blood-borne diseases to the patient. A primary reason why this technology is possible is that hamsters and humans:
- both use the same nucleotides in DNA.
- are closely related evolutionarily.
- both have similarly functioning immune systems.
- have plasmids that can be used as vectors.
Answer to question 40
- Answer Enter to expand or collapse answer. Answer expanded
- Correct Response: A. (Objective 0010) Genetic engineering allows for the recombination of two strands of DNA. In this recombinant DNA process, a human gene of interest is identified. The human gene is inserted into a hamster chromosome by using targeted enzymes to cut the human and hamster DNA at specific locations. The human gene then becomes incorporated into the hamster DNA. This process is possible because both organisms use DNA as their code to produce proteins and both organisms construct DNA from the same four nucleotides.
Correct Response: A. (Objective 0010) Genetic engineering allows for the recombination of two strands of DNA. In this recombinant DNA process, a human gene of interest is identified. The human gene is inserted into a hamster chromosome by using targeted enzymes to cut the human and hamster DNA at specific locations. The human gene then becomes incorporated into the hamster DNA. This process is possible because both organisms use DNA as their code to produce proteins and both organisms construct DNA from the same four nucleotides.