Abscisic acid synthesized in the root travels to different parts of the shoot where it regulates transpirational water loss. What is the most likely way that ABA travels from the root to the various locations within the shoot?

Question

A.  vessels and tracheids
B.  sieve tubes
C.  between cell walls
D.  from cell to cell through the plasmodesmata

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 transportation of materials within a plant? 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

A.  vessels and tracheids

Clarify Question
· What is the key concept addressed by the question?
        o This question is asking about the mode of transport from the roots to the stem for abscisic acid.
· What type of thinking is required?
        o You are being asked to take what you already know and apply it to the movement of abscisic acid within a plant.
· What key words does the question contain and what do they mean?
        o Abscisic acid, which is a plant hormone.
        o Transpirational water loss, which is the evaporation of water from the surface of a plant.

Gather Content
· What do you already know about transportation of materials within a plant? How does it relate to the question?
· Xylem, which is composed of vessels and tracheids, moves water and other materials from the roots up through the shoots to the leaves.
· Abscisic acid is made in the roots of plants.

Consider Possibilities
· What other information is related to the question? Which information is most useful?
        o Travel between cell walls or from cell to cell would be very inefficient.

Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o Abscisic acid is synthesized in the roots, and must travel upward.  The xylem and tracheids carry materials upward to the stem and leaves.

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 assess the route through which abscisic acid moves from the root to the stem of the plant. Answering this question correctly depended on your ability to use the characteristics of transport within a plant 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 abscisic acid is made in the roots, or that xylem carries material upward from the roots to the stem and leaves? Did you have trouble extending the routes of transport within a plant to determine the correct answer?