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23 Aug 2024, 12:26
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Question 1
B
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
95%
(hard)
Question Stats:
39% (02:53) correct
61%
(03:25) wrong
based on 134
sessions
History
Date
Time
Result
Not Attempted Yet
Question 2
D
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
75%
(hard)
Question Stats:
37% (01:18) correct 63%
(00:59) wrong
based on 168
sessions
History
Date
Time
Result
Not Attempted Yet
Question 3
A
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
95%
(hard)
Question Stats:
14% (01:20) correct 86%
(01:59) wrong
based on 160
sessions
History
Date
Time
Result
Not Attempted Yet
Question 4
E
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
95%
(hard)
Question Stats:
16% (00:52) correct 84%
(00:56) wrong
based on 155
sessions
History
Date
Time
Result
Not Attempted Yet
Question 5
E
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
25%
(medium)
Question Stats:
72% (00:46) correct 28%
(00:55) wrong
based on 128
sessions
History
Date
Time
Result
Not Attempted Yet
Ecological succession, a fundamental concept in ecology, refers to more-or-less predictable and orderly changes in the composition or structure of an ecological community. Succession may be initiated either by the formation of new, unoccupied habitat (e.g., a lava flow or a severe landslide) or by some form of disturbance (e.g. fire, severe wind throw, logging) of an existing community. The former case is often referred to as primary succession, the latter as secondary succession.
The trajectory of ecological change can be influenced by site conditions, by the interactions of the species present and by more stochastic factors such as availability of colonists or seeds or weather conditions at the time of disturbance. Some of these factors contribute to the predictability of successional dynamics; others add more probabilistic elements. In general, communities in early succession will be dominated by fast–growing well-dispersed species. As succession proceeds these species will tend to be replaced by more competitive species.
Trends in ecosystem and community properties in succession have been suggested, but few appear to be general. For example, species diversity almost necessarily increases during early succession as new species arrive, but may decline in later succession as competition eliminates opportunistic species and leads to dominance by locally superior competitors. Net primary production, biomass and trophic properties all show variable patterns over succession, depending on the particular system and site.
Ecological succession was formerly seen as having a stable end-stage called the climax, sometimes referred to as the 'potential vegetation' of a site, shaped primarily by the local climate. This idea has been largely abandoned by modern ecologists in favor of non-equilibrium ideas of how ecosystems function. Most natural ecosystems experience disturbance at a rate that makes a "climax" unattainable. Climate change often occurs at a rate and frequency sufficient to prevent arrival at a climax state. Additions to available species pools through range expansions and introductions can also continually reshape communities.
Many species are specialized to exploit disturbances. In the forests of northeastern North America, trees such as Betula alleghaniensis (Yellow birch) and Prunes serotina (Black cherry) are particularly well adapted to exploit large gaps in forest canopies, but are intolerant of shade and are eventually replaced by other species in the absence of disturbances that create such gaps.
The development of some ecosystem attributes, such as pedogenesis and nutrient cycles, is influenced by community properties, and, in turn, influences further community development. This process may occur only over centuries or millennia. Coupled with the stochastic nature of disturbance events and other long-term (e.g., climatic) changes, such dynamics make it doubtful whether the `climax' concept ever applies or is particularly useful in vegetation.
The trajectory of ecological change can be influenced by site conditions, by the interactions of the species present and by more stochastic factors such as availability of colonists or seeds or weather conditions at the time of disturbance. Some of these factors contribute to the predictability of successional dynamics; others add more probabilistic elements. In general, communities in early succession will be dominated by fast–growing well-dispersed species. As succession proceeds these species will tend to be replaced by more competitive species.
Trends in ecosystem and community properties in succession have been suggested, but few appear to be general. For example, species diversity almost necessarily increases during early succession as new species arrive, but may decline in later succession as competition eliminates opportunistic species and leads to dominance by locally superior competitors. Net primary production, biomass and trophic properties all show variable patterns over succession, depending on the particular system and site.
Ecological succession was formerly seen as having a stable end-stage called the climax, sometimes referred to as the 'potential vegetation' of a site, shaped primarily by the local climate. This idea has been largely abandoned by modern ecologists in favor of non-equilibrium ideas of how ecosystems function. Most natural ecosystems experience disturbance at a rate that makes a "climax" unattainable. Climate change often occurs at a rate and frequency sufficient to prevent arrival at a climax state. Additions to available species pools through range expansions and introductions can also continually reshape communities.
Many species are specialized to exploit disturbances. In the forests of northeastern North America, trees such as Betula alleghaniensis (Yellow birch) and Prunes serotina (Black cherry) are particularly well adapted to exploit large gaps in forest canopies, but are intolerant of shade and are eventually replaced by other species in the absence of disturbances that create such gaps.
The development of some ecosystem attributes, such as pedogenesis and nutrient cycles, is influenced by community properties, and, in turn, influences further community development. This process may occur only over centuries or millennia. Coupled with the stochastic nature of disturbance events and other long-term (e.g., climatic) changes, such dynamics make it doubtful whether the `climax' concept ever applies or is particularly useful in vegetation.
1. The passages suggested all of the following, EXCEPT:
A. Actual vegetation, in all probability, occurred since climax is unattainable.
B. If new ecosystem attributes do not develop, community development will stagnate.
C. Modern ecologists believe that the ecosystem cannot remain in equilibrium for extended periods of time.
D. Trends in ecosystem successions depend, to a large extent; on the particular system and its Location or site.
E. Competitive species generally do not dominate during the early stages of succession.
A. Actual vegetation, in all probability, occurred since climax is unattainable.
B. If new ecosystem attributes do not develop, community development will stagnate.
C. Modern ecologists believe that the ecosystem cannot remain in equilibrium for extended periods of time.
D. Trends in ecosystem successions depend, to a large extent; on the particular system and its Location or site.
E. Competitive species generally do not dominate during the early stages of succession.
2. According to the passage; which of the following determines the speed at which ecological changes take place?
I. formation of new habitats or disturbances in existing communities
II. Interaction of the species present
III. Site conditions and stochastic factors such as availability of colonists or seeds, or weather conditions at the time of disturbance
D. Only I
B. Only III
C. Only I and III
D. Only II and III
E. I, II and III
I. formation of new habitats or disturbances in existing communities
II. Interaction of the species present
III. Site conditions and stochastic factors such as availability of colonists or seeds, or weather conditions at the time of disturbance
D. Only I
B. Only III
C. Only I and III
D. Only II and III
E. I, II and III
3. Which of the following does the passage suggest about the ecosystem trends and community properties during succession?
I. Rapidly growing species are replaced by competition being selected in later stages.
II. Natural ecosystems do not achieve the 'climax' stage as a rate and frequency disturbances at 'a sufficient to prevent arrival at a climax state.
III. Community properties and ecosystem trends vary according to the site and the system.
IV. The trends in ecosystems and community properties are general in nature and cannot be classified.
A. Only III
B. Only I and III
C. Only II and IV
D. Only I
E. I, II, III and IV
I. Rapidly growing species are replaced by competition being selected in later stages.
II. Natural ecosystems do not achieve the 'climax' stage as a rate and frequency disturbances at 'a sufficient to prevent arrival at a climax state.
III. Community properties and ecosystem trends vary according to the site and the system.
IV. The trends in ecosystems and community properties are general in nature and cannot be classified.
A. Only III
B. Only I and III
C. Only II and IV
D. Only I
E. I, II, III and IV
4. What is the major difference between the nature of primary and secondary succession?
A. Primary succession consists of fast-growing, well-dispersed species while secondary dispersion mainly consists of more competitive species.
B. Primary succession has species which are not adaptable while secondary succession has species specialized to exploit disturbances in ecosystems:
C. Primary succession is the presence of a new unoccupied habitat while secondary succession indicates some form of disturbance to an existing community:
D. The site conditions, the interactions of species present, and more stochastic factors, such as availability of colonists or seeds or weather conditions.
E. The method of initiation of change in composition or structure of an ecological system.
A. Primary succession consists of fast-growing, well-dispersed species while secondary dispersion mainly consists of more competitive species.
B. Primary succession has species which are not adaptable while secondary succession has species specialized to exploit disturbances in ecosystems:
C. Primary succession is the presence of a new unoccupied habitat while secondary succession indicates some form of disturbance to an existing community:
D. The site conditions, the interactions of species present, and more stochastic factors, such as availability of colonists or seeds or weather conditions.
E. The method of initiation of change in composition or structure of an ecological system.
5. According to the passage, pedogenesis and nutrient cycles are different forms of ________.
A. community properties
B. stochastic properties
C. ecosystem trends
D. succession attributes
E. ecosystem attributes
A. community properties
B. stochastic properties
C. ecosystem trends
D. succession attributes
E. ecosystem attributes
25 Aug 2024, 04:41
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Hi, Please can you explain all the answers?
1. The given answer is B but it seems that the last para contradicts the answer, specifically this statement : "The development of some ecosystem attributes, such as pedogenesis and nutrient cycles, is influenced by community properties, and, in turn, influences further community development".
3. II and III both seem correct supported by below lines in the passage however that doesnt seem to be listed as an option.
For II : "Most natural ecosystems experience disturbance at a rate that makes a "climax" unattainable. Climate change often occurs at a rate and frequency sufficient to prevent arrival at a climax state."
For III : "Net primary production, biomass and trophic properties all show variable patterns over succession, depending on the particular system and site."
4. It seems that the initial point of difference between the primary and the secondary is marked by the fundamental change in how they commence supported by this line in passage. Should the answer not be C? "Succession may be initiated either by the formation of new, unoccupied habitat (e.g., a lava flow or a severe landslide) or by some form of disturbance (e.g. fire, severe wind throw, logging) of an existing community. The former case is often referred to as primary succession, the latter as secondary succession."
1. The given answer is B but it seems that the last para contradicts the answer, specifically this statement : "The development of some ecosystem attributes, such as pedogenesis and nutrient cycles, is influenced by community properties, and, in turn, influences further community development".
3. II and III both seem correct supported by below lines in the passage however that doesnt seem to be listed as an option.
For II : "Most natural ecosystems experience disturbance at a rate that makes a "climax" unattainable. Climate change often occurs at a rate and frequency sufficient to prevent arrival at a climax state."
For III : "Net primary production, biomass and trophic properties all show variable patterns over succession, depending on the particular system and site."
4. It seems that the initial point of difference between the primary and the secondary is marked by the fundamental change in how they commence supported by this line in passage. Should the answer not be C? "Succession may be initiated either by the formation of new, unoccupied habitat (e.g., a lava flow or a severe landslide) or by some form of disturbance (e.g. fire, severe wind throw, logging) of an existing community. The former case is often referred to as primary succession, the latter as secondary succession."
25 Aug 2024, 20:04
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Official answers may please be provided.
