A large watermelon fruit is very heavy and contains nearly 90% water. Since the skin of a watermelon is thick and lacks stomata, transpiration does not "pull" water into the watermelon. So, how does all that water get into the fruit?

Question

A.  Root pressure pushes water into the watermelon.
B.  Water enters by osmosis from the soil.
C.  Water is pumped in by active transport.
D.  Water is transported in the phloem along with the sugars while they are being translocated into the fruit.
E.  Watermelons, like other fruit, contain an abundance of xylem.


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 water moves through the tissues in 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

D.  Water is transported in the phloem along with the sugars while they are being translocated into the fruit.

Clarify Question
What is the key concept addressed by the question?
        · The key concept in this question is the movement of water into a fruit.
What type of thinking is required?
                o You are being asked to take what you already know and apply it to the heavy water content of a fruit.
What key words does the question contain and what do they mean?
        · Stomata are small opening on leaves that allow gas exchange to occur, but also allow water loss through evaporation.
        · Transpiration, which is the process of pulling water into a plant through the roots via the evaporation of water through the leaves.

Gather Content
What do you already know about how water moves through the tissues in a plant? How does it relate to the question?
        · The question tells you that water cannot enter the watermelon through transpiration or through the stomata. You know that the phloem is heavy in solutes, as it carries sugars and other nutrients in a water-based solution. Since this material in the phloem is solute-heavy, it is hypertonic, and has lower water potential. Solutions with lower water potential such as this would receive water from surrounding tissues, which would have higher water potential.

Consider Possibilities
What other information is related to the question? Which information is most useful?
        · Actively transporting water into a watermelon would be energetically costly and unnecessary. Xylem already inside the watermelon would not help to transport water into the watermelon. The question tells you that the skin of the watermelon is thick, so that would not promote the movement of water from the soil directly into the watermelon.

Choose Answer
Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        · The question itself tells you it is not feasible for water to flow directly from the environment into the watermelon due to the thick skin and lack of stomata on the watermelon. To answer this question, you must recall the internal consistency of the watermelon. The watermelon becomes a sink for the hypertonic sap that is carried in the phloem.

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?
        · This question asked you to take what you know about the flow of materials within a plant, and apply it to the synthesis of fruit. Answering this question correctly depended on your ability to use the nature of the fluid within the phloem 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 fluid within the phloem is hypertonic, or that the skin of a watermelon is too thick to allow water to flow in? Did you have trouble extending the nature of the fluid in the phloem to determine the correct answer?