Question 232·Medium·Rhetorical Synthesis
While researching a topic, a student has taken the following notes:
- The Venus flytrap closes in about one tenth of a second after prey touches one of its sensitive trigger hairs.
- Electrical signals generated by the touched hair race through the leaf.
- These signals cause cells along the leaf’s edges to rapidly change internal water pressure.
- While open, the leaf is slightly bent outward, storing elastic energy like a compressed spring.
- The sudden pressure change releases that stored energy, snapping the two lobes shut and trapping the prey.
The student wants to explain how the Venus flytrap is able to shut so quickly.
Which choice most effectively uses relevant information from the notes to accomplish this goal?
For rhetorical synthesis questions like this, first underline the task words in the question (here, “explain how” and “so quickly”). Then scan the notes to outline the full cause-and-effect chain in your own words. Next, eliminate any choices that (1) only restate one note, (2) leave out key steps in the process, or (3) add outside information not in the notes. Choose the option that uses multiple relevant notes to directly achieve the stated purpose in one clear, concise sentence.
Hints
Focus on the question’s key word: "how"
Ask yourself: which option explains the process that makes the flytrap close so quickly, instead of just telling you that it closes quickly?
Look for multiple linked steps from the notes
Review the notes about electrical signals, water pressure changes, and stored elastic energy. Which answer choice connects several of these ideas together?
Check for both cause and effect
You need a choice that includes what starts the closing (the trigger) and what happens inside the plant that makes the trap snap shut so fast.
Step-by-step Explanation
Clarify the task in the question
The question says the student wants to explain how the Venus flytrap is able to shut so quickly.
This means the answer must:
- Focus on the mechanism (cause-and-effect process), not just a description.
- Connect that mechanism to the speed of the closing.
Pull out the key mechanism details from the notes
From the notes, the process works like this:
- Prey touches a trigger hair.
- That touch generates electrical signals that race through the leaf.
- These signals cause cells along the leaf’s edges to rapidly change internal water pressure.
- While open, the leaf is bent outward, storing elastic energy like a compressed spring.
- The sudden pressure change releases that stored energy, snapping the two lobes shut.
A strong answer will include several of these linked steps, showing how touch leads to a fast snap.
Match the answer choices to the student’s goal
Now compare each choice to the goal (explain how it shuts so quickly) and the full chain from the notes:
- Some wrong answers will only mention how fast it closes, without explaining the process.
- Others will give just one part of the process (like stored energy or pressure change) but not connect the chain from touch to rapid closing.
- The correct answer should tie together the trigger, internal signals/pressure changes, and release of stored energy into one clear explanation.
Eliminate choices that are incomplete or off-focus
Evaluate each option:
- Choice A mainly emphasizes the closing speed and trapping the insect, but it doesn’t explain the internal mechanism that makes the snap possible.
- Choice C focuses on the leaf storing elastic energy, but it doesn’t explain what triggers the closing or how that energy gets released quickly.
- Choice D mentions a pressure change and closing, but it leaves out the triggering touch and the stored elastic energy that explains the speed.
That leaves one choice that clearly and efficiently links the key steps into a single explanation.
Identify the choice that fully explains the rapid mechanism
The only option that strings together the key steps—touch causing electrical signals, those signals quickly changing cell pressure, and that pressure change releasing stored elastic energy to produce a rapid snap—is:
An insect’s touch triggers electrical signals that rapidly change cell pressure, releasing stored elastic energy that snaps the trap shut.