- What is the primary function of decomposers in an ecosystem?
A) They capture solar energy for photosynthesis.
B) They consume primary consumers for energy.
C) They break down dead organic matter and recycle nutrients.
D) They produce oxygen as a byproduct of metabolism.
Answer: C) They break down dead organic matter and recycle nutrients.
Explanation:
Decomposers, like fungi and bacteria, break down dead plants and animals, recycling nutrients back into the ecosystem and making them available for producers.
- Which of the following is an example of an ecological niche?
A) The number of organisms in a population
B) The physical space an organism occupies
C) The role an organism plays in its environment, including how it gets its food
D) The temperature range of an ecosystem
Answer: C) The role an organism plays in its environment, including how it gets its food.
Explanation:
An ecological niche includes all the biotic and abiotic factors that an organism interacts with in its environment, including its role in the food web, habitat, and its interactions with other species.
- Which of the following is an example of a keystone species?
A) A predator that has a large effect on the structure of the community
B) A species that has a large population and few natural predators
C) A species that outcompetes others for resources
D) A species that is at the top of the food chain but does not affect other species
Answer: A) A predator that has a large effect on the structure of the community.
Explanation:
A keystone species has a disproportionately large impact on its ecosystem relative to its biomass or abundance. For example, wolves in Yellowstone control the population of deer, which affects the vegetation and overall ecosystem structure.
- What is the term for a species that plays a critical role in maintaining the structure of an ecological community?
A) Pioneer species
B) Keystone species
C) Invasive species
D) Indicator species
Answer: B) Keystone species
Explanation:
Keystone species play a critical role in maintaining the structure and function of their ecological community. Their removal can cause significant changes in the ecosystem.
- Which of the following best describes “symbiosis”?
A) A type of competition between two species.
B) A close, long-term interaction between two different species.
C) The division of resources among organisms in the same area.
D) A form of predation where one species kills another.
Answer: B) A close, long-term interaction between two different species.
Explanation:
Symbiosis is a long-term interaction between two different species that can be mutualistic, parasitic, or commensal.
- Which of the following is true about a population that exhibits exponential growth?
A) The population size increases rapidly at a constant rate.
B) The population size remains constant over time.
C) The population grows more slowly as it approaches the carrying capacity.
D) The population experiences cyclical fluctuations.
Answer: A) The population size increases rapidly at a constant rate.
Explanation:
Exponential growth occurs when a population grows at a constant rate, with no limitations on resources or space. The growth rate is proportional to the current population size.
- What does the term “community” refer to in ecology?
A) The physical environment where organisms live.
B) All the organisms of the same species in a particular area.
C) The interaction of different species living in the same area.
D) The sum of all the ecosystems in a region.
Answer: C) The interaction of different species living in the same area.
Explanation:
In ecology, a community refers to all the different species living and interacting in the same area, including their relationships with each other and the environment.
- What is the difference between “primary succession” and “secondary succession”?
A) Primary succession occurs after a disturbance, while secondary succession occurs in a previously uninhabited area.
B) Primary succession occurs on bare rock or soil, while secondary succession occurs in areas that have previously supported life.
C) Secondary succession is slower than primary succession.
D) There is no difference between primary and secondary succession.
Answer: B) Primary succession occurs on bare rock or soil, while secondary succession occurs in areas that have previously supported life.
Explanation:
Primary succession happens in a newly formed or barren environment (e.g., after a volcanic eruption), whereas secondary succession occurs in an area that has previously been occupied by living organisms but was disturbed (e.g., after a forest fire).
- What is the main characteristic of an “exponential growth curve”?
A) It is a J-shaped curve where population size grows rapidly without constraints.
B) It shows a stable population size over time.
C) It is a linear increase in population size.
D) It plateaus as resources become limiting.
Answer: A) It is a J-shaped curve where population size grows rapidly without constraints.
Explanation:
Exponential growth occurs when there are no limiting factors such as food, space, or predation, and the population grows rapidly at a constant rate.
- Which of the following describes a “climatic factor” in an ecosystem?
A) The type of food consumed by a species
B) The temperature and humidity of the environment
C) The number of species present in an area
D) The amount of soil organic matter
Answer: B) The temperature and humidity of the environment
Explanation:
Climatic factors refer to abiotic factors such as temperature, humidity, light, and precipitation, which influence the types of organisms that can live in an ecosystem.
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