The water in a damaged root is seeping between cells and not moving into the vascular tissue. What part of the root has been damaged?

Question

A.  Primary vascular tissue
B.  Pith
C.  Root hairs
D.  Casparian strip
E.  Root cap

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  the functions of the different tissues in plant roots?? 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.  Casparian strip

Clarify Question
· What is the key concept addressed by the question?
        o Plant roots have different tissues that each play a role in the functions of the root.
· What type of thinking is required?
        o You must apply what you know about individual tissues of the root to identify an area of damage with a root.
· What key words does the question contain and what do they mean?
        o Seeping, which means the tissue is leaking unexpectedly.
        o Vascular tissue, which is the xylem and phloem.
        o Root, which is the structure through which water enters the plant and is moved upward toward the stem and leaves.

Gather Content
· What do you already know about  the functions of the different tissues in plant roots?? How does it relate to the question?
        o The Casparian strip regulates water flow into the xylem.
        o Damage to this strip would allow seeping of water before it reached the xylem.

Consider Possibilities
· What other information is related to the question? Which information is most useful?
        o Root hair cells and the root cap are external to the main body of the root.  Damage to those structures would not result in internal seeping of water.

Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o Since the seeping so water is not reaching the vascular tissue, you know that the pathway for water from the roots to the vascular tissue has been compromised.  To answer this question, you must recognize the path is the Casparian strip.  Only damage to the Casparian strip could cause this seeping.

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 damage to a plant root.   Answering this question correctly depended on your ability to use plant root 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 the Casparian strip regulates water flow into the xylem, or that xylem is a component of the vascular tissue? Did you have trouble extending concept X to determine the correct answer?