Crosscutting: Cause and Effect Flashcards

In a marine ecosystem, a sudden, dramatic increase in the sea otter population leads to a sharp decline in sea urchins. Subsequently, kelp forests, which are heavily grazed by sea urchins, begin to flourish. Which of the following BEST describes the relationship between the sea otter increase and the flourishing kelp forests?

Answer: An indirect cause-and-effect relationship.

This scenario illustrates an indirect cause-and-effect relationship, also known as a trophic cascade. The increase in sea otters (cause) does not directly cause the kelp to flourish. Instead, it causes a decrease in sea urchins (an intermediate effect), and the reduction of sea urchins (the direct cause) allows the kelp forests to thrive (the final effect).

A climate scientist observes that as global average temperatures rise, the amount of ice and snow cover at the poles decreases. This exposes darker ocean and land surfaces, which absorb more solar radiation, leading to a further increase in global temperatures. This phenomenon is best classified as:

Answer: A reinforcing positive feedback loop.

This is a classic example of a reinforcing positive feedback loop in the climate system. The initial effect (warming) causes a change (melting ice) that amplifies the original effect, leading to more warming. Unlike negative feedback loops which stabilize a system, positive feedback loops can lead to runaway conditions or accelerated change.

A researcher notes a strong correlation between the number of storks nesting in a region and the human birth rate in that same region over several years. They conclude that the presence of storks is a direct cause of the increase in human births. Why is this conclusion likely flawed?

Answer: A hidden or lurking variable is likely the cause of both observed trends.

This is a classic example of mistaking correlation for causation due to a lurking or confounding variable. In this case, a variable like urbanization or economic development could be the true cause. For example, economic growth might lead to both more construction (creating nesting spots for storks on new buildings) and families feeling stable enough to have more children. The storks and birth rates are correlated, but neither causes the other.

In a complex system like a forest ecosystem, a small, localized event such as a lightning strike causing a small fire can sometimes trigger a massive, landscape-altering wildfire under the right conditions (e.g., drought, high winds). This disproportionate effect is an example of:

Answer: A system reaching a tipping point or threshold.

This scenario describes a system at a tipping point, where a small cause can trigger a large, often irreversible effect. The ecosystem is primed by drought and wind conditions, and the small fire acts as the catalyst that pushes it over a threshold, leading to a catastrophic shift in the system's state. The effect is disproportionately large compared to the initial cause.

Which of the following scenarios best illustrates the scientific concept of 'multiple causation,' where a single effect results from several interacting causes?

Answer: The development of antibiotic resistance in bacteria due to overuse of antibiotics and natural selection pressures.

The development of antibiotic resistance is a multifaceted problem resulting from the interaction of multiple causes. These include the widespread use and misuse of antibiotics in medicine and agriculture (the selective pressure), the natural genetic variation within bacterial populations, and the rapid reproductive rate of bacteria that allows for quick proliferation of resistant strains. The other options describe simpler, more direct cause-and-effect relationships.

An ER doctor fails to diagnose a patient's critical condition. The patient is discharged and later suffers a severe injury during a physical therapy session that would not have been prescribed if the correct diagnosis was made. In this chain of events, the doctor's failure to diagnose is best described as:

Answer: An indirect cause of the physical therapy injury.

This is an example of indirect causation. The doctor's misdiagnosis did not, by itself, physically harm the patient. However, it created the conditions under which the subsequent harm from the physical therapy could occur. The direct cause was the physical therapy action, but that action was a foreseeable consequence of the initial failure to diagnose, making the misdiagnosis an indirect cause.