Question 200·Hard·Rhetorical Synthesis
While researching aquatic ecosystems, a student has compiled the following notes:
- Eutrophication occurs when a body of water becomes enriched with nutrients such as nitrogen and phosphorus.
- Excess nutrients spur the rapid growth of algae, creating algal blooms.
- When algal blooms die, the decomposition process consumes dissolved oxygen in the water.
- A severe reduction in dissolved oxygen, called hypoxia, can kill fish and other aquatic organisms.
- Major human contributors to eutrophication include agricultural runoff and untreated sewage.
The student wants to explain why algal blooms can result in fish die-offs. Which choice most effectively uses relevant information from the notes to accomplish this goal?
For rhetorical synthesis questions like this, start by rephrasing the task in your own words (for example, “I need a sentence that explains how X leads to Y”). Then skim the notes and mark only the bullets that relate directly to that task, especially any that show cause-and-effect. Build a mental or quick written chain of events from those notes, and finally choose the option that captures that full chain without adding unrelated details or stopping halfway. Eliminate choices that only define terms, mention causes without consequences, or give consequences without tying them back to the starting point named in the question.
Hints
Focus on the task word "why"
The question is asking why algal blooms can result in fish die-offs. Look for a choice that explains the mechanism (the steps in between), not just a definition or a cause of eutrophication.
Use the most relevant notes
From the notes, which bullets mention both what happens after algal blooms and how fish or other organisms can die? Those are the pieces your answer should be built from.
Check for a complete chain of events
Ask yourself: Does this option connect algal blooms to something that changes the water, and then to fish dying? Eliminate choices that stop at nutrients, growth of algae, or just naming hypoxia without linking it clearly to the blooms and to death.
Step-by-step Explanation
Restate what the question is asking
The prompt asks: Why can algal blooms result in fish die-offs? That means your answer must show a clear cause-and-effect chain starting from algal blooms and ending with fish (and other aquatic life) dying.
Find the relevant notes in the list
Look back at the bullet points and identify which ones talk about:
- Algal blooms
- Something happening after the blooms
- The death of fish or other aquatic organisms
The key notes are:
- “Excess nutrients spur the rapid growth of algae, creating algal blooms.”
- “When algal blooms die, the decomposition process consumes dissolved oxygen in the water.”
- “A severe reduction in dissolved oxygen, called hypoxia, can kill fish and other aquatic organisms.”
Determine the key cause-and-effect chain
From those notes, piece together the sequence:
- Nutrients cause algal blooms.
- When the algae die, they decompose.
- Decomposition uses up dissolved oxygen in the water.
- Low oxygen (hypoxia) can kill fish and other aquatic life.
So the best sentence must connect algal blooms to decomposition to loss of oxygen to death of aquatic organisms, not just describe nutrients or define terms like eutrophication or hypoxia.
Eliminate choices that don’t answer the specific "why"
Now check each option against that cause-and-effect chain:
- One choice talks mainly about where the nutrients come from (human activities) but does not explain how blooms cause fish to die.
- Another explains that eutrophication adds nutrients and causes algal growth, but stops before getting to fish die-offs.
- A third defines hypoxic conditions and says they are evidence of eutrophication, but still doesn’t explain how blooms themselves lead to fish deaths.
Only one choice clearly explains that the decomposition of algae from blooms removes oxygen from the water, which then kills aquatic life.
Match the cause-and-effect chain to the correct option
The choice that uses the notes to show that decomposing algae after nutrient-driven blooms consume dissolved oxygen, which then suffocates aquatic life, is:
B) Decomposition of algae after nutrient-driven blooms depletes dissolved oxygen, suffocating aquatic life.