BSC2011 Exam 1 |52 Complete Questions and Answers
28.1 How can the steps in the table be ordered to describe a plant's response to an invading
pathogen? - -2, 5, 4, 1, 3
-28.1 Which action could help a biologist determine whether a particular plant population
had been attacked by a bacterial pathogen in the recent past? - -Look for elevated levels of
mRNA transcripts for PR proteins in tissues of plants sampled across the population.
-28.1 Plants of different species showed different responses to the same pathogen as
summarized in the table above. Which of the following hypotheses best explains all of the
observations? - -Species B is able to defend against the pathogen with a hypersensitive
response, whereas species A does not mount this defense.
-28.1 In systemic acquired resistance, which molecule is transported throughout the plant?
- -Salicylic acid
-25.3 Which would you expect to increase the rate of water transport in a plant? - -A rise
in temperature
-25.3 According to the current model of fluid flow in xylem, what creates the force that
moves water from the roots to the leaves? - -An increase in water tension in leaves
-25.3 Where does the energy come from that drives water transport in plants? - -The sun
-25.3 What structures allow water vapor to escape the leaves of a plant? - -Stomata
-25.4 Movement of sucrose and other carbohydrates through the phloem in a plant is
called - -translocation.
-25.4 The flowchart describes the mechanism underlying fluid flow in phloem. Which
phrases best fill in the blanks? - -A = Water movement by osmosis; B = Pressure increase
-25.4 In the spring, a plant grows from a root system that had been dormant throughout
the winter. The plant produces a stem, several branches, leaves, and begins to flower. The
relative concentrations of sucrose in cells of various organs of the plant are shown in the
table. How would you describe the fluid pressure in the plant phloem at this time? - -
Highest in root and lowest in flower bud
-25.4 Which of the following statements about the pressure flow model of fluid flow in
phloem is true? - -Sucrose concentrations determine the direction of the fluid flow.
-27.1 In an angiosperm, a megaspore mother cell is _______ and undergoes _______ to produce
four haploid (n) megaspores. - -diploid (2n); meiosis
, -27.1 In a female reproductive organ of an angiosperm, a multinucleate structure with
eight haploid nuclei forms. This structure is known as the - -embryo sac.
-27.1 What evolutionary advantage might be gained by a plant carrying out double
fertilization instead of single fertilization? - -The plant conserves energy by producing a
food source for zygotes only when zygotes are successfully formed.
-27.1 If you were to analyze the source of the genetic material in an angiosperm
endosperm, what ratio of maternal to paternal material would you find? - -2:1
-26.2 A biologist isolates cells that are not actively producing auxin from a section of a
plant stem. She places them in a culture dish with a growth medium that keeps the cells
alive. When she adds auxin to the dish, the cells begin synthesizing more cellulose. What is
an alternative that the biologist could add instead of auxin that would allow her to observe
the same response? - -acid
-26.2 When a plant is illuminated from one side, auxin is transported to the _______ side of
the shoot, where it stimulates cells to _______, causing the shoot to bend toward the light. - -
dark; expand
-26.2 A biologist investigating the response of a particular plant species to light cues
stumbles upon three mutant plant lines. Each displays a lack of normal phototropic
behavior but varies in the auxin concentrations present in their growing tips. Based on the
information given in the table, what could explain the behaviors of the three mutants? - -
Mutant 1 is deficient in an enzyme involved in auxin biosynthesis, whereas mutants 2 and 3
may have defective expansin and/or proton pump proteins.
-26.2 Which is the correct order of events during auxin-mediated cell elongation? - -
Proton pump gene expression → ATP hydrolysis → H+ movement into cell wall → expansin
activation
-19.1 Morphologically, archaea differ from bacteria because they lack peptidoglycan
molecules in their cell walls. Archaea differ from eukarya because they lack a membrane-
bound nucleus. What can be concluded about when these two features evolved along the
phylogenetic tree shown in the figure? - -Peptidoglycans evolved sometime after point 2,
and membrane-bound nuclei evolved sometime after point 3.
-19.1 According to genetic evidence, two main lines of descent emerged from the last
universal common ancestor. One of these lines gave rise to the - -Archaea and Eukarya.
-19.1 Why were ribosomal RNA molecules (rRNA) so important in showing the
relationships between organisms in the three domains? - -Because rRNA is basic to all cells
and its sequence reveals phylogenetic information
-19.1 Genomes of three different organisms were sequenced. Each organism represents
one of the three domains of life as indicated in the top row of the table. A comparison of the
28.1 How can the steps in the table be ordered to describe a plant's response to an invading
pathogen? - -2, 5, 4, 1, 3
-28.1 Which action could help a biologist determine whether a particular plant population
had been attacked by a bacterial pathogen in the recent past? - -Look for elevated levels of
mRNA transcripts for PR proteins in tissues of plants sampled across the population.
-28.1 Plants of different species showed different responses to the same pathogen as
summarized in the table above. Which of the following hypotheses best explains all of the
observations? - -Species B is able to defend against the pathogen with a hypersensitive
response, whereas species A does not mount this defense.
-28.1 In systemic acquired resistance, which molecule is transported throughout the plant?
- -Salicylic acid
-25.3 Which would you expect to increase the rate of water transport in a plant? - -A rise
in temperature
-25.3 According to the current model of fluid flow in xylem, what creates the force that
moves water from the roots to the leaves? - -An increase in water tension in leaves
-25.3 Where does the energy come from that drives water transport in plants? - -The sun
-25.3 What structures allow water vapor to escape the leaves of a plant? - -Stomata
-25.4 Movement of sucrose and other carbohydrates through the phloem in a plant is
called - -translocation.
-25.4 The flowchart describes the mechanism underlying fluid flow in phloem. Which
phrases best fill in the blanks? - -A = Water movement by osmosis; B = Pressure increase
-25.4 In the spring, a plant grows from a root system that had been dormant throughout
the winter. The plant produces a stem, several branches, leaves, and begins to flower. The
relative concentrations of sucrose in cells of various organs of the plant are shown in the
table. How would you describe the fluid pressure in the plant phloem at this time? - -
Highest in root and lowest in flower bud
-25.4 Which of the following statements about the pressure flow model of fluid flow in
phloem is true? - -Sucrose concentrations determine the direction of the fluid flow.
-27.1 In an angiosperm, a megaspore mother cell is _______ and undergoes _______ to produce
four haploid (n) megaspores. - -diploid (2n); meiosis
, -27.1 In a female reproductive organ of an angiosperm, a multinucleate structure with
eight haploid nuclei forms. This structure is known as the - -embryo sac.
-27.1 What evolutionary advantage might be gained by a plant carrying out double
fertilization instead of single fertilization? - -The plant conserves energy by producing a
food source for zygotes only when zygotes are successfully formed.
-27.1 If you were to analyze the source of the genetic material in an angiosperm
endosperm, what ratio of maternal to paternal material would you find? - -2:1
-26.2 A biologist isolates cells that are not actively producing auxin from a section of a
plant stem. She places them in a culture dish with a growth medium that keeps the cells
alive. When she adds auxin to the dish, the cells begin synthesizing more cellulose. What is
an alternative that the biologist could add instead of auxin that would allow her to observe
the same response? - -acid
-26.2 When a plant is illuminated from one side, auxin is transported to the _______ side of
the shoot, where it stimulates cells to _______, causing the shoot to bend toward the light. - -
dark; expand
-26.2 A biologist investigating the response of a particular plant species to light cues
stumbles upon three mutant plant lines. Each displays a lack of normal phototropic
behavior but varies in the auxin concentrations present in their growing tips. Based on the
information given in the table, what could explain the behaviors of the three mutants? - -
Mutant 1 is deficient in an enzyme involved in auxin biosynthesis, whereas mutants 2 and 3
may have defective expansin and/or proton pump proteins.
-26.2 Which is the correct order of events during auxin-mediated cell elongation? - -
Proton pump gene expression → ATP hydrolysis → H+ movement into cell wall → expansin
activation
-19.1 Morphologically, archaea differ from bacteria because they lack peptidoglycan
molecules in their cell walls. Archaea differ from eukarya because they lack a membrane-
bound nucleus. What can be concluded about when these two features evolved along the
phylogenetic tree shown in the figure? - -Peptidoglycans evolved sometime after point 2,
and membrane-bound nuclei evolved sometime after point 3.
-19.1 According to genetic evidence, two main lines of descent emerged from the last
universal common ancestor. One of these lines gave rise to the - -Archaea and Eukarya.
-19.1 Why were ribosomal RNA molecules (rRNA) so important in showing the
relationships between organisms in the three domains? - -Because rRNA is basic to all cells
and its sequence reveals phylogenetic information
-19.1 Genomes of three different organisms were sequenced. Each organism represents
one of the three domains of life as indicated in the top row of the table. A comparison of the
