BSC2011 Exam 1

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 genomes revealed some regions of overlap between the organisms. Three regions, labeled 1 through 3 in the table, show overlap between at least two organisms as indicated by checkmarks. Of the three cases shown, which is/are most likely due to lateral gene transfer?

1

20.1 What would a biologist look for in order to determine whether a chloroplast in a cell evolved as the result of primary endosymbiosis or secondary endosymbiosis?

The number of membranes in the chloroplast

20.1 Based on information provided in the tutorial, which of the following pairs of organisms has the closest evolutionary relationship?

green algae and land plants

20.1 Which phrase could be used in a description of secondary endosymbiosis?

A eukaryote engulfing a eukaryote

20.1 What was the origin of all chloroplasts?

A single cyanobacterium

21.2 Which statement describes events leading to formation of offspring in the conifer life cycle?

A haploid sperm from pollen enters the female gametophyte and fuses with a haploid egg

21.2 How do the sporophyte and gametophyte generations compare in a conifer?

The sporophyte generation is much larger than the gametophyte generation and the two generations grow as a single individual.

21.2 The table lists structures associated with portions of the life cycle in a conifer. Where on this table could an arrow be placed to indicate when meiosis occurs?

In between the sporophyte and gametophyte headings

21.2 In conifers, male gametophytes are called ______ and are formed by the division of microspores.

pollen

21.3 A biologist discovers a seed-bearing plant that has never been classified. Which feature will help him determine whether the plant is a gymnosperm or an angiosperm?

Female structures that produce an egg enclosed in a protective structure

21.3 Which statement correctly describes the general pattern of the alternation of generations in angiosperms?

The sporophyte generation (2n) produces spores (n) that produce gametophytes (n) that produce gametes (n) that fuse to produce a new sporophyte (2n).

21.3 Which structure is not a part of the sporophyte generation?

egg

21.3 Double fertilization, which is a hallmark of angiosperm sexual reproduction, results in a

diploid zygote and a triploid endosperm.

24.1 A biologist takes core samples from three tree stems and uses them to determine the number of annual rings. How would the position of the vascular cambium in these three core samples compare?

The vascular cambium would be in different positions relative to the stem center in all three cases, with increasing distances from 3 to 1 to 2.

24.1 If you examined a cross section of a eudicot plant stem, in what order would you encounter different plant tissues from the pith outward?

Xylem, vascular cambium, phloem

24.1 A biologist counts the rings of a tree trunk to determine its age. What is the identity of the tissue in the rings being analyzed?

Secondary xylem

24.1 How does primary growth differ from secondary growth in plants?

Primary growth results in height changes; secondary growth results in width changes.

What is the genetic relationship between a gametophyte and the gametes it produces?

The gametophyte and its gametes are genetically identical

Which of the following would NOT stop movement of water through the xylem?

Treating the plant with a drug that makes stomata open.

If a plant needs to move sugars from the leaves to the roots, will this "cost" the plant energy?

Yes

Some bryophytes can self fertilize, where mitotically produced eggs and sperm from the same gametophyte fuse and form a completely homozygous sporophyte. Then, the spores produced after meiosis will be genetically identical. Could this happen in a heterosporus plant?

No

Is the fern life cycle shown here that of a homosporous or a heterosporus fern?

Homosporous

What does the casparian strip ensure?

That water must cross a cell membrane before being transported into the root

What is the source of energy that powers the raising of water from the soil to the leaves?

Solar energy in the form of heat.

Evaluate the following statement: A large tree is mostly dead.

True, the tracheids and vessels are dead at maturity

Choose the statement that is TRUE about relatedness of the embryonic sporophyte, the megagametophyte, and the seed coat/integument.

The three tissues are each genetically different individuals

Gymnosperm seeds have storage tissue that is ( ) while angiosperm seeds storage tissue that is ( ).

haploid; triploid

These flowers came from a single shrub. Because the one on the left is () and the one on the right is (), this plant species is best described as ().

Female; Male; Monoecious

Photorespiration is a problem for plants for what reason?

Carbon dioxide is not used as efficiently because active sites on RuBisCo are occupied by oxygen