Question

Oscillation of Predator and Prey Populations



Source: Oxford Designers & Illustrators Ltd/Pearson Education Ltd



On the graph (above), a healthy, stable predator-prey oscillation is shown. The blue line represents the population of a prey species, while the red line represents the population of a predator species. Assume that this specific predator eats this specific prey.

3. Use the graph above to determine if each statement (below) is accurate or inaccurate.

Scoring: Earn 1 point by getting 2 or 3 correct responses. Earn 2 points by getting 4 correct responses.

(2 points)
Accurate Inaccurate
There must always be a higher population of predators than prey in order for both populations to survive.


The two populations have no affect on each other. The fluctuations are just random.


A decrease in the prey population causes a subsequent decrease in the predator population because competition for food becomes more difficult.


An increase in the prey population causes a subsequent increase in the predator population because there is more food available for the predators.

Answer 1

To evaluate the accuracy of each statement regarding predator-prey dynamics based on the typical oscillation model, let's analyze each one:

1. **"There must always be a higher population of predators than prey in order for both populations to survive."**
- **Inaccurate**: Typically, the prey population is higher than the predator population. Predators rely on prey for survival, but they do not need to outnumber them.

2. **"The two populations have no effect on each other. The fluctuations are just random."**
- **Inaccurate**: Predator and prey populations are interdependent. The fluctuations in one population will affect the other, as seen in the oscillatory dynamics.

3. **"A decrease in the prey population causes a subsequent decrease in the predator population because competition for food becomes more difficult."**
- **Accurate**: As prey numbers decrease, predators will have less food available, leading to a decline in their population.

4. **"An increase in the prey population causes a subsequent increase in the predator population because there is more food available for the predators."**
- **Accurate**: When prey populations increase, predators have ample food supply, which supports an increase in their population.

So the evaluation results in:
- Statement 1: Inaccurate
- Statement 2: Inaccurate
- Statement 3: Accurate
- Statement 4: Accurate

Based on this analysis, you have 2 accurate statements (3 and 4), which means you score **2 points**.