Question

question 20 (1 point)
secondary succession occurs when...
a all living and nonliving components are completely destroyed
b a disturbance leaves soil intact but damages the community
c communities develop on bare rock with no soil present
d a climax community reaches its final stage

question 21 (1 point)
what term describes a stable, final community that forms at the \end\ of succession?
a pioneer species
b primary community
c keystone species
d climax community

Explanation:

Question 20

To determine when secondary succession occurs, we analyze each option:

• Option a: Describes a scenario where all living and non - living components are completely destroyed. This is more like the start of primary succession (which starts on bare rock with no soil or life remnants), so a is incorrect.
• Option b: A disturbance that leaves soil intact but damages the community. Secondary succession occurs in areas where the soil is still present (as it was in a previously established ecosystem that was disturbed), so this matches the definition of secondary succession.
• Option c: Communities developing on bare rock with no soil present is primary succession (since there's no pre - existing soil), so c is incorrect.
• Option d: A climax community reaching its final stage is not related to the start of secondary succession. Secondary succession is about the recovery of a disturbed ecosystem, not the climax stage itself.

• Pioneer species: These are the first species to colonize a barren area, not the final stable community.
• Primary community: Primary succession leads to a community, but the term for the stable final community is not primary community.
• Keystone species: A keystone species is one that has a disproportionately large effect on its environment relative to its abundance, not related to the final stage of succession.
• Climax community: By definition, a climax community is a stable, final community that forms at the end of ecological succession.

Answer:

b. A disturbance leaves soil intact but damages the community

Question 21