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Pre AP Biology -ECO 4.1 Interspecific Competition- MCQ Exam Style Questions -New Syllabus

Pre AP Biology -ECO 4.1 Interspecific Competition- FRQ Exam Style Questions – New Syllabus 2025-2026

Pre AP Biology -ECO 4.1 Interspecific Competition- FRQ Exam Style Questions – Pre AP Biology – per latest Pre AP Biology Syllabus.

Pre AP Biology – FRQ Exam Style Questions- All Topics

Question

Lake Superior is on the northern border of the continental United States. The graph below shows changes in the size of the moose population on an island in Lake Superior from (1960) to (2005). The island is in a remote location several miles off the northwest shore of the lake.
a. Explain why immigration and emigration are not likely to have an effect on the size of the island’s moose population.
b. Describe what happened to the size of the island’s moose population from (1995) to (1997), and describe how the birth rate and the death rate must have compared during this time.
c. Identify and explain two different natural factors that could have contributed to the change in moose population size you described in part (b).

Most-appropriate topic codes (Pre-AP Biology):

• TOPIC: ECO 2.1 — Population Structure: Factors defining the niche and distribution of a species, including physical barriers — part (a)
• TOPIC: ECO 2.2 — Population Growth: Analyzing population growth patterns, the relationship between birth/death rates, and factors like carrying capacity and density-dependent regulation — parts (b), (c)
• TOPIC: ECO 4.1 — Interspecific Competition: Understanding how predator-prey dynamics and competition for resources shape community structure — part (c)
• Science Practice — Strategic Use of Mathematics: Using data from graphs to explain the growth or decline of a population — part (b)
• Science Practice — Emphasis on Analytical Reading and Writing: Extracting relevant information from text and data to support scientific claims — parts (a), (c)
▶️ Answer/Explanation
Detailed solution

(a)
The moose are on an isolated island, so they cannot emigrate from the area, and new moose cannot immigrate. Because the island is in a “remote location several miles off the shore,” the water creates a significant physical barrier. In ecological terms, this creates a closed population where population growth is determined solely by births and deaths, effectively making migration rates negligible.

(b)
The population of the moose dramatically decreased (crashed) from (1995) to (1997), dropping from approximately (2400) individuals to roughly (500). Regarding the rates: the death rate increased significantly and exceeded the birth rate. While the absolute number of births decreased because there were fewer surviving adults to reproduce, the defining characteristic of this decline is that mortality (death rate) was much higher than natality (birth rate).

(c)
Two natural factors that likely contributed to this crash are:
1. Resource Depletion (Running out of food): The population reached a very high peak in (1995), likely exceeding the island’s carrying capacity. This high density would lead to overgrazing, causing a food shortage (density-dependent factor) and subsequent starvation, drastically increasing the mortality rate.
2. Predation: Predator-prey populations respond dynamically to each other. As the prey (moose) population increased, it would support a larger predator population (e.g., wolves). Increased predation pressure would then drive the moose mortality rate up, contributing to the population crash.

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