AZSCI Crosscutting: Cause and Effect 1 — Questions and Answers
Question 1: In a coastal area, the removal of mangrove forests for development leads to increased flooding and erosion during storms. What is the most direct cause-and-effect relationship described?
- Cause: Increased flooding; Effect: Removal of mangroves.
- Cause: Coastal development; Effect: Growth of mangrove forests.
- Cause: Removal of mangroves; Effect: Increased storm intensity.
- Cause: Removal of mangroves; Effect: Reduced protection from storm surge. (Correct answer)
Correct answer: Cause: Removal of mangroves; Effect: Reduced protection from storm surge.
The mangroves serve as a natural barrier that absorbs the energy of storm surges. The cause is the removal of the mangroves. The direct effect is the loss of this protection, which in turn leads to the secondary effects of increased flooding and erosion.
Question 2: A student observes that their potted plant is wilting. They hypothesize that a lack of water is the cause. To test this, they water the plant and observe that it becomes firm again. This experiment helps to:
- Prove that all plants wilt without water.
- Establish a correlation between watering and plant health.
- Identify the mechanism of water transport in plants.
- Strengthen the evidence for a causal link between lack of water and wilting. (Correct answer)
Correct answer: Strengthen the evidence for a causal link between lack of water and wilting.
By manipulating a single variable (adding water) and observing the predicted effect (recovery from wilting), the student has provided evidence that supports a cause-and-effect relationship. It moves beyond a simple observation to a test of the proposed cause.
Question 3: Data shows that ice cream sales and the number of shark attacks both increase during the summer. Concluding that eating ice cream causes shark attacks is flawed because:
- The data is likely inaccurate.
- Correlation does not imply causation; a third factor (hot weather) is the likely cause of both. (Correct answer)
- Shark attacks cause people to want to eat ice cream.
- There is no statistical relationship between the two variables.
Correct answer: Correlation does not imply causation; a third factor (hot weather) is the likely cause of both.
This is a classic example of correlation versus causation. Two variables can trend together without one causing the other. A hidden or confounding variable, in this case, hot weather, is the actual cause that leads to both more people swimming (increasing shark encounter risk) and more people eating ice cream.
Question 4: The eruption of a large volcano can release massive amounts of ash and sulfur dioxide into the stratosphere. What is a likely effect on the global climate in the year or two following the eruption?
- A slight global warming due to the heat released from the volcano.
- No significant effect on the global climate.
- A slight global cooling as the particles block sunlight. (Correct answer)
- An increase in acid rain, but no temperature change.
Correct answer: A slight global cooling as the particles block sunlight.
The cause is the injection of aerosols (fine particles) into the stratosphere. The mechanism is that these particles reflect incoming solar radiation back into space before it can warm the surface. The effect is a temporary cooling of the Earth's average temperature.
Question 5: In the process of natural selection, what is the direct cause of an increase in the frequency of a beneficial trait in a population over many generations?
- The random mutation that first created the trait.
- The desire of the organisms to have that trait.
- The trait providing a survival or reproductive advantage in a specific environment. (Correct answer)
- The migration of new organisms lacking the trait into the population.
Correct answer: The trait providing a survival or reproductive advantage in a specific environment.
Natural selection is the mechanism. The cause of a trait becoming more common is that individuals possessing that trait are more successful at surviving and reproducing in their specific environment, thus passing the trait to a greater proportion of the next generation.
Question 6: A ball is rolled down a ramp. Which change would cause the ball to have greater kinetic energy at the bottom of the ramp?
- Using a ball with less mass.
- Decreasing the steepness of the ramp.
- Starting the ball from a higher point on the ramp. (Correct answer)
- Making the surface of the ramp rougher to increase friction.
Correct answer: Starting the ball from a higher point on the ramp.
The cause is the change in the setup, and the effect is the change in kinetic energy. Starting the ball from a higher point increases its initial gravitational potential energy (PE = mgh). Due to the conservation of energy, this greater initial potential energy will be converted into greater kinetic energy (KE = 1/2mv²) at the bottom.
Question 7: A doctor explains that chronic high blood pressure is a major cause of heart disease. What is the underlying mechanism that links this cause and effect?
- High blood pressure makes a person feel more stressed, which damages the heart.
- High blood pressure damages the walls of arteries, making them prone to plaque buildup. (Correct answer)
- People with high blood pressure tend to have a poor diet, and the diet causes heart disease.
- High blood pressure causes the heart to beat slower, which weakens the heart muscle.
Correct answer: High blood pressure damages the walls of arteries, making them prone to plaque buildup.
Cause-and-effect relationships are often mediated by a specific mechanism. In this case, the constant high force of the blood (cause) physically damages the delicate inner lining of the arteries. This damage is the mechanism that leads to inflammation and atherosclerosis (plaque buildup), which is a form of heart disease (effect).
AZSCI Crosscutting: Cause and Effect 1
In a coastal area, the removal of mangrove forests for development leads to increased flooding and erosion during storms.
What is the most direct cause-and-effect relationship described?