Answer key
Check your answers from every chapter here
Chapter 3
A small birthday candle is weighed, then lighted and placed beneath a metal can containing 100 mL of water. Careful records are kept as the temperature of the water rises. Data from this experiment are shown on the graph. What amount of heat energy is released in the burning of candle wax?
A) 0.5 kilocalories per gram of wax burned - Correct Answer
B) 5 kilocalories per gram of wax burned
C) 10 kilocalories per gram of wax burned
D) 20 kilocalories per gram of wax burned
E) 50 kilocalories per gram of wax burned
Carbon dioxide (CO₂) is readily soluble in water, according to the equation CO₂ + H₂O ↔ H₂CO₃. Carbonic acid (H₂CO₃) is a weak acid. If CO₂ is bubbled into a beaker containing pure, freshly distilled water, which of the following graphs correctly describes the results?
Chapter 6
A) microfilaments and the nuclear lamina
B) microtubules and cleavage furrow formation
C) microfilaments and ciliary motion
D) intermediate filaments and cytoplasmic streaming
E) microtubules and chromosome movement - Correct Answer
Which of the trees in this figure groups the domains according to similarities in cellular size and architecture?
A) A - Correct Answer
B) B
C) C
D) D
Chapter 7
Five dialysis bags, constructed from a semipermeable membrane that is impermeable to sucrose, were filled with various concentrations of sucrose and then placed in separate beakers containing an initial concentration of 0.6 M sucrose solution. At 10-minute intervals, the bags were massed (weighed) and the percent change in mass of each bag was graphed.
Which line in the graph represents the bag that contained a solution isotonic to the 0.6 M solution at the beginning of the experiment?
A) A
B) B
C) C - Correct Answer
D) D
E) E
Which line in the graph represents the bag with the highest initial concentration of sucrose?
A) A - Correct Answer
B) B
C) C
D) D
E) E
Which line or lines in the graph represent(s) bags that contain a solution that is hypertonic at 50 minutes?
A) A and B
B) B - Correct Answer
C) C
D) D
E) D and E
Chapter 8
Which curve(s) on the graphs may represent the temperature and pH profiles of an enzyme taken from a bacterium that lives in a mildly alkaline hot springs at temperatures of 70°C or higher?
A) curves 1 and 5
B) curves 2 and 4
C) curves 2 and 5
D) curves 3 and 4
E) curves 3 and 5 - Correct Answer
Which temperature and pH profile curves on the graphs were most likely generated from analysis of an enzyme from a human stomach where conditions are strongly acid?
A) curves 1 and 4 - Correct Answer
B) curves 1 and 5
C) curves 2 and 4
D) curves 2 and 5
E) curves 3 and 4
Chapter 9
Figure 9.3 shows the electron transport chain. Which of the following is the combination of substances that is initially added to the chain?
A) oxygen, carbon dioxide, and water
B) NAD⁺, FAD, and electrons
C) NADH, FADH₂, and protons
D) NADH, FADH₂, and O₂ - Correct Answer
E) oxygen and protons
Which of the following most accurately describes what is happening along the electron transport chain in Figure 9.3?
A) Chemiosmosis is coupled with electron transfer.
B) Each electron carrier alternates between being reduced and being oxidized. - Correct Answer
C) ATP is generated at each step.
D) Energy of the electrons increases at each step.
E) Molecules in the chain give up some of their potential energy.
Which of the protein complexes labeled with Roman numerals in Figure 9.3 will transfer electrons to O₂?
A) complex I
B) complex II
C) complex III
D) complex IV - Correct Answer
E) All of the complexes can transfer electrons to O₂.
Chapter 10
Figure 10.1 shows the absorption spectrum for chlorophyll a and the action spectrum for photosynthesis. Why are they different?
A) Green and yellow wavelengths inhibit the absorption of red and blue wavelengths.
B) Bright sunlight destroys photosynthetic pigments.
C) Oxygen given off during photosynthesis interferes with the absorption of light.
D) Other pigments absorb light in addition to chlorophyll a. - Correct Answer
E) Aerobic bacteria take up oxygen, which changes the measurement of the rate of photosynthesis.
What wavelength of light in the figure is most effective in driving photosynthesis?
A) 420 mm - Correct Answer
B) 475 mm
C) 575 mm
D) 625 mm
E) 730 mm
Chapter 11
Which of the following types of signaling is represented in the figure?
A) autocrine
B) paracrine
C) hormonal
D) synaptic - Correct Answer
E) long distance
In the figure, the dots in the space between the two structures represent which of the following?
A) receptor molecules
B) signal transducers
C) neurotransmitters
D) hormones
E) pheromones
Chapter 12
In the figure above, mitosis is represented by which numbered part(s) of the cycle?
A) I
B) II
C) III
D) IV - Correct Answer
E) V
G₁ is represented by which numbered part(s) of the cycle?
A) I or V - Correct Answer
B) II or IV
C) III only
D) IV only
E) V only
Which number represents DNA synthesis?
A) I
B) II - Correct Answer
C) III
D) IV
E) V
Chapter 13
A certain (hypothetical) organism is diploid, has either blue or orange wings as the consequence of one of its genes on chromosome 12, and has either long or short antennae as the result of a second gene on chromosome 19, as shown in Figure 13.4.
A certain female's number 12 chromosomes both have the blue gene and number 19 chromosomes both have the long gene. As cells in her ovaries undergo meiosis, her resulting eggs (ova) may have which of the following?
A) either two number 12 chromosomes with blue genes or two with orange genes
B) either two number 19 chromosomes with long genes or two with short genes
C) either one blue or one orange gene in addition to either one long or one short gene
D) one chromosome 12 with one blue gene and one chromosome 19 with one long gene - Correct Answer
Chapter 14
What is the genotype of the deceased individual in generation II?
A) homozygous for a gene for colon cancer
B) homozygous for both cancer alleles from his mother
C) heterozygous for a gene for colon cancer - Correct Answer
D) affected by the same colon cancer environmental factor as his mother
E) carrier of all of the several known genes for colon cancer
In each generation of this family after generation I, the age at diagnosis is significantly lower than would be found in nonfamilial (sporadic) cases of this cancer (~ 63 years). What is the most likely reason?
A) Members of this family know to be checked for colon cancer early in life.
B) Hereditary (or familial) cases of this cancer typically occur at earlier ages than do nonfamilial forms. - Correct Answer
C) This is pure chance; it would not be expected if you were to look at a different family.
D) This cancer requires mutations in more than this one gene.
E) Affected members of this family are born with colon cancer, and it can be detected whenever they are first tested.
From this pedigree, how does this trait seem to be inherited?
A) from mothers
B) as an autosomal recessive
C) as a result of epistasis
D) as an autosomal dominant - Correct Answer
E) as an incomplete dominant
Chapter 15
A plantlike organism on the planet Pandora can have three recessive genetic traits: bluish leaves, due to an allele (a) of gene A; a feathered stem, due to an allele (b) of gene B; and hollow roots due to an allele (c) of gene C. The three genes are linked and recombine as follows:
A geneticist did a testcross with an organism that had been found to be heterozygous for the three recessive traits and she was able to identify progeny of the following phenotypic distribution (+ = wild type): (See Image)
What is the greatest benefit of having used a testcross for this experiment?
A) The homozygous recessive parents are obvious to the naked eye.
B) The homozygous parents are the only ones whose crossovers make a difference.
C) Progeny can be scored by their phenotypes alone. - Correct Answer
D) All of the progeny will be heterozygous.
E) The homozygous recessive parents will be unable to cross over.
The greatest distance among the three genes is between a and c. What does this mean?
A) Gene a is closest to b.
B) Genes are in the order: a–b–c.
C) Gene a is not recombining with c.
D) Gene a is between b and c. - Correct Answer
E) Distance a–b is equal to distance a–c.
Chapter 19
In 1971, David Baltimore described a scheme for classifying viruses based on how the virus produces mRNA.
The table below shows the results of testing five viruses for nuclease specificity, the ability of the virus to act as an mRNA, and presence (+) or absence (-) of its own viral polymerase (SEE IMAGE)
Given Baltimore's scheme, a positive sense single-stranded RNA virus such as the polio virus would be most closely related to which of the following?
A) T-series bacteriophages
B) retroviruses that require a DNA intermediate - Correct Answer
C) single-stranded DNA viruses such as herpes viruses
D) nonenveloped double-stranded RNA viruses
E) linear double-stranded DNA viruses such as adenoviruses
Based on the above table, which virus meets the Baltimore requirements for a retrovirus?
A) A
B) B
C) C
D) D - Correct Answer
E) E
Chapter 20
The DNA profiles that follow represent four different individuals.
Which of the following statements is consistent with the results?
A) B is the child of A and C.
B) C is the child of A and B. - Correct Answer
C) D is the child of B and C.
D) A is the child of B and C.
E) A is the child of C and D.
Which of the following statements is most likely true?
A) D is the child of A and C.
B) D is the child of A and B. - Correct Answer
C) D is the child of B and C.
D) A is the child of C and D.
E) B is the child of A and C.
Which of the following are probably siblings?
A) A and B
B) A and C
C) A and D
D) C and D - Correct Answer
E) B and D
Chapter 21
Figure 21.1 Types of DNA sequences in the human genome.
The pie chart in Figure 21.1 represents the relative frequencies of the following in the human genome:
I. repetitive DNA unrelated to transposons
II. repetitive DNA that includes transposons
III. unique noncoding DNA
IV. introns and regulatory sequences
V. exons
Which region is occupied by exons only (V)?
A) A - Correct Answer
B) B
C) C
D) D
E) E
Which region includes Alu elements and LI sequences?
A) A
B) B
C) C
D) D
E) E - Correct Answer
Chapter 22
The following questions refer to the evolutionary tree in Figure 22.2.
The horizontal axis of the cladogram depicted below is a timeline that extends from 100,000 years ago to the present; the vertical axis represents nothing in particular. The labeled branch points on the tree (V—Z) represent various common ancestors. Let's say that only since 50,000 years ago has there been enough variation between the lineages depicted here to separate them into distinct species, and only the tips of the lineages on this tree represent distinct species.
How many separate species, both extant and extinct, are depicted in this tree?
A) two
B) three
C) four
D) five
E) six - Correct Answer
According to this tree, what percent of the species seem to be extant (in other words, not extinct)?
A) 25%
B) 33%
C) 50%
D) 66% - Correct Answer
E) 75%
Chapter 23
Anopheles mosquitoes, which carry the malaria parasite, cannot live above elevations of 5,900 feet. In addition, oxygen availability decreases with higher altitude. Consider a hypothetical human population that is adapted to life on the slopes of Mt. Kilimanjaro in Tanzania, a country in equatorial Africa. Mt. Kilimanjaro's base is about 2,600 feet above sea level and its peak is 19,341 feet above sea level. If the incidence of the sickle-cell allele in the population is plotted against altitude (feet above sea level), which of the following distributions is most likely, assuming little migration of people up or down the mountain? - Correct Answer B
If global warming permits mosquitoes to live at higher altitudes than they currently do, then in which direction should the entire plot in the correct distribution below be shifted?
A) to the right - Correct Answer
B) to the left
C) upward
D) downward
Chapter 24
In the ocean, on either side of the Isthmus of Panama, are 30 species of snapping shrimp; some are shallow-water species, others are adapted to deep water. There are 15 species on the Pacific side and 15 different species on the Atlantic side. The Isthmus of Panama started rising about 10 million years ago. The oceans were completely separated by the isthmus about 3 million years ago.
Why should deepwater shrimp on different sides of the isthmus have diverged from each other earlier than shallow-water shrimp?
A) They have been geographically isolated from each other for a longer time. - Correct Answer
B) Cold temperatures, associated with deep water, have accelerated the mutation rate, resulting in faster divergence in deepwater shrimp.
C) The rise of the land bridge was accompanied by much volcanic activity. Volcanic ash contains heavy metals, which are known mutagens. Ash fall caused high levels of heavy metals in the ocean sediments underlying the deep water, resulting in accelerated mutation rates and faster divergence in deepwater shrimp.
D) Fresh water entering the ocean from the canal is both less dense and cloudier than seawater. The cloudy fresh water interferes with the ability of shallow-water shrimp to locate mating partners, which reduces the frequency of mating, thereby slowing the introduction of genetic variation.
In the following figure, the isthmus separates the Pacific Ocean on the left (side A) from the Atlantic Ocean on the right (side B). The seawater on either side of the isthmus is separated into five depth habitats (1—5), with 1 being the shallowest.
In which habitat should one find snapping shrimp most closely related to shrimp that live in habitat A4?
A) A3
B) A5
C) B4 - Correct Answer
D) either A3 or A5
E) any species from any one of the side A habitats
Chapter 25
The figure represents a cross section of the sea floor through a mid-ocean rift valley, with alternating patches of black and white indicating sea floor with reversed magnetic polarities. At the arrow labeled "I" (the rift valley), the igneous rock of the sea floor is so young that it can be accurately dated using carbon-14 dating. At the arrow labeled "III," however, the igneous rock is about 1 million years old, and potassium-40 dating is typically used to date such rocks. Note: The horizontal arrows indicate the direction of sea-floor spreading, away from the rift valley.
Assuming that the rate of sea-floor spreading was constant during the 1-million-year period depicted above, Earth's magnetic field has undergone reversal at an average rate of once every
A) 10,000 years.
B) 25,000 years.
C) 100,000 years.
D) 250,000 years. - Correct Answer
E) 1,000,000 years.
Which section of sea-floor crust should have the thickest layer of overlying sediment, assuming a continuous rate of sediment deposition?
A) A
B) B
C) C
D) D
E) E - Correct Answer
If a particular marine organism is fossilized in the sediments immediately overlying the igneous rock at the arrow labeled "II," at which other location, labeled A—E, would a search be most likely to find more fossils of this organism?
A) B only
B) C only - Correct Answer
C) D only
D) B and C
E) C and D
Chapter 27
Figure 27.2 depicts changes to the amount of DNA present in a recipient cell that is engaged in conjugation with an Hfr cell. Hfr cell DNA begins entering the recipient cell at Time A. Assume that reciprocal crossing over occurs (in other words, a fragment of the recipient's chromosome is exchanged for a homologous fragment from the Hfr cell's DNA). Use Figure 27.2 to answer the following question.
Figure 27.2
What is occurring at Time C that is decreasing the DNA content?
A) crossing over
B) cytokinesis
C) meiosis
D) degradation of DNA that was not retained in the recipient's chromosome - Correct Answer
E) reversal of the direction of conjugation
How is the recipient cell different at Time D than it was at Time A?
A) It has a greater number of genes.
B) It has a greater mass of DNA.
C) It has a different sequence of base pairs. - Correct Answer
D) It contains bacteriophage DNA.
E) Its membrane-bound DNA pumps are inactive.
Chapter 30
The following questions refer to the generalized life cycle for land plants shown in Figure 30.1. Each number within a circle or square represents a specific plant or plant part, and each number over an arrow represents either meiosis, mitosis, or fertilization.
Figure 30.1
In Figure 30.1, which number represents the mature gametophyte?
A) 1
B) 3
C) 5
D) 7 - Correct Answer
E) 11
In Figure 30.1, which number represents an embryo?
A) 1
B) 3
C) 7
D) 9
E) 11 - Correct Answer
Meiosis is most likely to be represented by which number(s) in Figure 30.1?
A) 2
B) 4 - Correct Answer
C) 2 and 8
D) 4 and 8
E) 10 and 12
