Viruses travel through animals mainly by lysing cells and then spreading to other cells. Plant cells are not easily lysed. If a pathogen enters a plant cell and does not initiate a hypersensitive response, what is the most likely way the virus would spread to other plant cells?

Question

A.  Through the chloroplasts.
B.  Directly through the cell wall.
C.  Through the central vacuole.
D.  Through the plasmodesmata.
E.  Through transport vesicles.

Clarify Question
· What is the key concept addressed by the question?
· What type of thinking is required?
· What key words does the question contain and what do they mean?

Gather Content
· What do you already know about how plant viruses spread between cells? How does it relate to the question?

Consider Possibilities
· What other information is related to the question? Which information is most useful?

Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?

Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

D.  Through the plasmodesmata.


Clarify Question
· What is the key concept addressed by the question?
        o This question asks you to identify how a virus can exit a plant cell.
· What type of thinking is required?
        o You are being asked to take what you already know and apply it to how a virus can work within plant tissue.
· What key words does the question contain and what do they mean?
        o Virus, which is a submicroscopic, potentially infectious parasite.
        o Lysed, which is the rupture of a cell membrane when viruses break out of a cell.
        o Pathogen, which is a disease-causing agent.

Gather Content
· What do you already know about how plant viruses spread between cells? How does it relate to the question?
        o Plant cells have a cell wall outside of the cell membrane.
        o The cell wall of a plant cell provides support for the cell.
        o Plasmodesmata are small channels that allow plant cells to interact with their environment.
        o The hypersensitive response seals off a wounded or infected area by causing cell death.

Consider Possibilities
· What other information is related to the question? Which information is most useful?
        o Chloroplasts and the central vacuole occur within a cell, and would not provide a pathway out of the cell.
        o The cell wall is composed of cellulose, and does not allow for the free flow of materials by itself.

Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o To spread to other cells, viruses need a pathway through the cell wall. The plasmodesmata are such a pathway.

Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
· Apply level:
        o This question asked you to determine how a virus can exit a plant cell. Answering this question correctly depended on your ability to use plant cell structure in a new situation. If you got the correct answer, great job! If you got an incorrect answer, where did the process break down? Did you remember that plant cells differ from animal cells in that plant cells have cell walls, or that plasmodesmata allow materials to move in and out of plant cells? Did you have trouble extending plant cell structure to determine the correct answer?