# Conflicting Viewpoints in Biology
Conflicting Viewpoints passages present two or more scientists/students with different explanations for the same biological phenomenon. You must understand each viewpoint, identify where they agree and disagree, and evaluate which is better supported by evidence.
1. How Conflicting Viewpoints Work
Structure
- Background: Describes the phenomenon or observation
- Scientist/Student 1: Presents one explanation with supporting reasoning
- Scientist/Student 2: Presents an alternative explanation
- Sometimes a Scientist 3 offers a third perspective
What You Need to Do
- Summarise each viewpoint in 1-2 sentences
- Identify the key disagreement — what specific claim differs?
- Note any shared assumptions or agreed-upon facts
- Determine what evidence would support or weaken each viewpoint
2. Common Biology Debate Topics on the ACT
Ecology
- What controls population size: top-down (predators) vs. bottom-up (resources)?
- Is a species decline due to habitat loss or disease?
Genetics & Evolution
- Is a trait primarily genetic or environmental?
- What is the cause of a phenotypic change: mutation, natural selection, or genetic drift?
Physiology
- What mechanism explains an observed physiological response?
- Is a disease caused by bacteria, viruses, or environmental factors?
Cell Biology
- Different models for how a cellular process works
- Competing hypotheses about the origin of organelles
3. Worked Example
Background: A lake's fish population declined by 50% over 5 years.
Scientist 1: The decline is caused by increased water temperature due to climate change. Warmer water holds less dissolved oxygen, stressing fish. Data shows average water temperature rose 2°C over the period.
Scientist 2: The decline is caused by an invasive predatory species introduced 6 years ago. Stomach content analysis of the invasive species shows it feeds heavily on the native fish. Temperature change alone wouldn't cause this rapid a decline.
Q1: On what do both scientists agree?
A1: Both agree that the fish population declined by 50% over 5 years. They disagree on the cause of the decline.
Q2: What evidence would most weaken Scientist 1's argument?
A2: If other lakes with similar temperature increases showed no decline in fish populations, this would suggest temperature alone is not sufficient to cause the decline.
Q3: What evidence would most weaken Scientist 2's argument?
A3: If the invasive species was found to eat primarily other organisms (not the declining fish species), or if the decline began before the invasive species was introduced, this would weaken the predation hypothesis.
4. Strategy Tips
- Read the background first — understand the phenomenon before reading viewpoints
- Annotate each viewpoint — underline the key claim and evidence
- Make a comparison: What does Scientist 1 say that Scientist 2 doesn't, and vice versa?
- For "strengthen/weaken" questions: Think about what new evidence would make each hypothesis more or less likely
- Don't pick sides based on your own knowledge — use only the passage information
5. Practice Questions
Q1. Scientist 1 argues a plant's wilting is due to drought. Scientist 2 argues it's due to root infection by a fungus. What experiment could distinguish between the two?
A1. Grow identical plants in two groups: one with adequate water but exposed to the fungus, and one with reduced water but no fungus. If only the water-stressed group wilts, drought is the cause. If only the fungus group wilts, infection is the cause. If both wilt, both factors may contribute.
Q2. Two scientists disagree about why a bird species has larger beaks on one island. Scientist A says it's natural selection for harder seeds. Scientist B says it's a plastic response to diet (not genetic). How could you test this?
A2. Raise chicks from the large-beaked island on the same diet as the small-beaked island population. If beak size remains large, it's genetic (supporting Scientist A). If beak size decreases, it's a plastic/environmental response (supporting Scientist B).
Want to check your answers and get step-by-step solutions?
Summary
- Identify each viewpoint's core claim and supporting evidence
- Find agreements and disagreements between viewpoints
- Think about what new evidence would strengthen or weaken each position
- Answer using only the passage — not outside knowledge