Test on Key Concepts in Population Ecology

Question 1: Fires in a forest typically lead to primary succession.

A. Ano

B. Ne

Explanation: Fires are an example of a disturbance that leads to secondary succession, as the soil remains after the event. Primary succession occurs where there were no previous plants and soil present before, such as on lava flows or severe landslips.

Question 2: Which of the following scenarios best illustrates resource partitioning, allowing species to achieve competitive co-existence?

A. One species outcompeting another, leading to the weaker species dying out.

B. Giraffes eating top leaves of a tree while kudu eat lower parts of the same tree.

C. The first species to colonize a new habitat, such as lichens on lava flows.

D. Species with identical ecological niches successfully inhabiting the same area without any differentiation in resource use.

Explanation: Competitive co-existence occurs when species co-exist in the same habitat or niche by accessing the same resources differently through resource partitioning. An example provided is giraffes eating top leaves and kudu eating lower parts of the same plant, demonstrating how different parts of the same resource are utilized. The other options describe competitive exclusion, pioneer species in primary succession, or a scenario that contradicts the definition of competitive co-existence through resource partitioning.

Question 3: Lichens are the first species to appear after a disturbance in secondary succession.

A. Ano

B. Ne

Explanation: Annuals (herbs and weeds) are the first species to appear after a disturbance in secondary succession. Lichens are the first species to become established on rock after a disturbance, which is characteristic of primary succession.

Question 4: Lichens primarily contribute to soil formation by adding substantial organic matter from their living tissues while breaking down rocks.

A. Ano

B. Ne

Explanation: Lichens contribute to soil formation by breaking down rocks into smaller pieces and, upon decomposition after death, adding small amounts of organic matter to the newly formed soil. The materials do not state they add substantial organic matter from their living tissues.

Question 5: Which characteristic enables lichens to be the first species to establish on rock during primary succession?

A. They require deep soil for anchorage and nutrients.

B. They do not need soil to survive.

C. They significantly enrich the soil with large amounts of organic matter upon decomposition.

D. They primarily thrive in environments with pre-existing rich organic soil.

Explanation: According to the study materials, lichens are the first species to become established on rock after a disturbance and 'They do not need soil to survive.' This characteristic allows them to colonize bare rock, initiating primary succession.