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:
- One type of wrong answer will only mention how fast it closes, without explaining the process.
- Another type will give just one part of the process (like stored energy or cell pressure) but not connect it fully 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 restates that the trap closes in a fraction of a second and adds “according to biophysicists,” but it doesn’t explain the internal mechanism.
- Choice C focuses on the leaf bending outward and storing elastic energy, but doesn’t show how this leads to rapid closure starting from an insect touch.
- Choice D mentions cell pressure changes and closing, but leaves out the initial trigger (touch/electricity) and the idea of stored energy being released to make it so fast.
That leaves one choice that clearly and efficiently links touch → electrical signal → pressure change → release of stored energy → fast snap.
Identify the choice that fully explains the rapid mechanism
The only option that strings together the key steps—an insect’s touch creating electrical signals, those signals quickly changing cell pressure, and that pressure change releasing stored elastic energy to slam the trap shut—is:
B) Electricity travels through the Venus flytrap when an insect touches it, producing a fast change in cell pressure that releases stored elastic energy and slams the trap shut.