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Questions and Answers
What is the study of interactions between organisms and their environment called?
A population consists of organisms from different species living together in the same habitat.
False
What is a species in ecological terms?
A group of organisms that can interbreed and produce fertile offspring.
A __________ refers to all the populations of different species living in the same habitat.
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Match the following ecological terms with their definitions:
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What happens to energy as it flows through an ecosystem?
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All ecosystems have the same physical and living components.
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Name two types of organisms that can be found in Hong Kong's freshwater streams.
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Energy flows from one organism to another in the form of ____ when organisms are eaten by others.
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Match the types of ecosystems in Hong Kong with their characteristics:
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Study Notes
Ecosystems
- Hong Kong has many different natural environments
- Organisms in an ecosystem interact with one another and with their environment, creating stable, self-supporting systems
- Different types of ecosystems exist in Hong Kong, including freshwater streams, mangroves, woodlands, grasslands, and rocky shores
- Key characteristics vary between ecosystems (e.g. water availability, temperature, soil type.)
Ecology
- Ecology is the study of interrelationships between organisms and their environment
- Levels of organization include species, populations, communities, ecosystems, biomes, and biosphere
- Organisms within a habitat have specific interactions to maintain a self-supporting/stable/dynamic ecosystem
Abiotic Factors
- Abiotic factors are non-living components of an ecosystem
- Examples include temperature, light, rainfall, humidity, wind speed, water current, salinity, oxygen level, and substratum characteristics
- These factors greatly affect organism distribution in ecosystems, and organisms have adaptations in response to these factors
Biotic factors
- Biotic factors are the living components of an ecosystem
- Populations of organisms may compete, interact in mutualistic, commensalistic, and parasitic relationships, or engage in predation.
- The species richness and abundance in a community determine its species diversity; the influence of a dominant species on diversity
- Common terms refer to niche and habitat. Habitat is an organism's address, and a niche is an organism's role in a community. Niche attributes are (1) temperature range the organism resides in, (2) types of food the organism eats and (3) the space it occupies. A population of two species cannot coexist if their niches are the same.
Energy Flow in Ecosystems
- Energy flow is not a cyclic process, instead is lost as heat through many processes
- Organisms in different trophic levels (producer, primary, secondary, tertiary) transfer chemical energy
- Energy flow through a food chain
- Energy lost in different activities (respiration, uneaten materials, excretion, undigested matter).
- Role of decomposers: Break down organic matter and release nutrients into the soil, which is necessary for producers to grow.
Ecosystem Succession
- Ecological succession is the gradual change in the plant and animal communities in a habitat over time/process of ecological change
- Primary succession occurs in areas where no soil exists (e.g. after a glacier retreats or volcanic eruption)
- Pioneer species colonize barren areas, gradually forming soil, and eventually forming a climax community of plants.
- Secondary succession takes place in areas that once had soil and organisms (e.g. after a fire)
- The pioneer species are often grasses, shrubs, and small trees that are capable of colonizing the area rapidly
- A climax community eventually is formed.
Ecological Pyramids
- Pyramids of numbers and biomass summarize energy transfer within a food chain
- Pyramids generally narrow as trophic levels increase, reflecting the loss of energy between levels
- Pyramid of numbers reflects number of organisms at each trophic level
- Pyramid of biomass shows total dry mass of organisms at each level
- Pyramids may also be inverted (e.g. a single tree supports many insects) due to differences in organism size, lifespan, and reproductive rate.
Conservation of Ecosystems
- Human activities have significantly impacted ecosystems
- Overexploitation, pollution, habitat destruction, and global warming cause harm
- Loss of biodiversity (variety of species) is one key result
- Conservation efforts are essential (e.g., waste reduction, habitat protection, alternative energy).
Sampling techniques
- Quadrat sampling: Used to estimate the abundance (density and percentage cover) of non-mobile/slow-moving organisms.
- Line transect sampling: Used to study the distribution of immobile organisms. It involves measuring the presence or absence of species along a line.
- Belt transect sampling: Involves sampling along a line using quadrats at regular intervals or continuously along the line, providing more accurate estimation of the abundance of organisms and identifying the transition between different communities
Material Cycling
- The carbon cycle involves the movement of carbon between the atmosphere, organisms, and the soil. Key processes include respiration, photosynthesis, combustion, and decomposition.
- The nitrogen cycle describes the movement of nitrogen, including nitrogen fixation (converting atmospheric nitrogen into usable forms for plants) and nitrification (converting ammonia to nitrates).
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Description
Test your knowledge on ecological concepts and interactions between organisms and their environments. This quiz covers topics related to species, habitats, ecosystems, and energy flow within ecological systems. Perfect for students studying ecology or environmental science!