2.1 Individuals, Populations, Communities & Ecosystems (DP IB Environmental Systems & Societies (ESS): SL): Flashcards
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Define biosphere.
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Define biosphere.
The biosphere is the narrow, life-supporting zone around the Earth where the atmosphere, hydrosphere and lithosphere meet.
Define species (biological species concept).
A species is a group of organisms sharing common characteristics that interbreed to produce fertile offspring.
Define population (in ecology).
A population is a group of organisms of the same species living in the same area at the same time, which interbreed.
True or False?
Ecosystems are closed systems in which matter can enter or exit, but energy cannot.
False.
Ecosystems are open systems in which both energy and matter can enter and exit.
Define community (in ecology).
A community is a collection of interacting populations of different species living in the same area at the same time.
Through which processes does energy mainly exit an ecosystem?
Energy mainly exits an ecosystem as heat, released during respiration and lost during trophic transfers.
Define habitat.
A habitat is the local environment in which an organism, species, population or community normally lives.
One species may consist of many populations; for example, the Eastern Grey Kangaroo has multiple populations across different regions of that rarely interbreed due to geographic isolation.
One species may consist of many populations; for example, the Eastern Grey Kangaroo has multiple populations across different regions of Australia that rarely interbreed due to geographic isolation.
Define ecosystem.
An ecosystem is a community of living organisms, together with their physical environment, interacting as a system within a specific area.
How does energy typically enter an ecosystem?
Energy typically enters an ecosystem when photosynthetic organisms, such as plants and algae, capture sunlight.
Matter can enter or exit ecosystems in the form of water, nutrients, gases or produced by animals.
Matter can enter or exit ecosystems in the form of water, nutrients, gases or waste produced by animals.
Define classification (in biology).
Classification is the process of organising and categorising species into groups based on the biological characteristics they share.
The hierarchical classification system, from most general to most specific, is: Domain, Kingdom, Phylum, Class, Order, Family, Genus, .
The hierarchical classification system, from most general to most specific, is: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.
Define genus.
A genus is a category in the classification hierarchy that includes one or more closely related species sharing common characteristics.
In the binomial name Homo sapiens, which part is the genus name?
Homo is the genus name in Homo sapiens.
True or False?
In a binomial name, both the genus and species names are written with a capital letter.
False.
Only the genus name is capitalised; the species name is not.
Which well-known genus includes species such as the grey wolf, domestic dog and coyote?
The genus Canis includes species such as the grey wolf, domestic dog and coyote.
Define dichotomous key.
A dichotomous key is a tool used to identify organisms through a series of paired statements or questions, each with two possible answers.
Which identification method compares an organism's DNA sequence with known sequences stored in large databases?
DNA surveys compare an organism's DNA sequence with known sequences stored in large databases.
True or False?
DNA surveys are generally less precise than other identification methods when distinguishing closely related species.
False.
DNA surveys provide precise and reliable identification, especially for closely related species.
Which identification method involves physically comparing an unknown specimen with a collection of already-identified organisms?
Comparison with reference collections involves physically comparing an unknown specimen with a collection of already-identified organisms.
One limitation of dichotomous keys is that they are limited to physical characteristics and may not account for factors such as behaviour or .
One limitation of dichotomous keys is that they are limited to physical characteristics and may not account for factors such as behaviour or habitat.
Why can a dichotomous key sometimes produce an inaccurate identification?
A dichotomous key can produce an inaccurate identification if it is poorly designed or lacks important distinguishing characteristics.
Define biotic factors.
Biotic factors are the living, biological components of an ecosystem and the interactions between organisms within it.
Define abiotic factors.
Abiotic factors are the non-living, physical factors that influence the organisms within an ecosystem.
Grey squirrels were introduced to the UK in the 1800s and have since outcompeted native red squirrels for resources; they also carry a pathogen that red squirrels have no to.
Grey squirrels were introduced to the UK in the 1800s and have since outcompeted native red squirrels for resources; they also carry a pathogen that red squirrels have no resistance to.
Which invasive predator, introduced to Australia in the 1800s for recreational hunting, has caused declines in native small mammal and bird species?
The red fox was introduced to Australia in the 1800s and has caused declines in native small mammal and bird species.
Define ecological niche.
An ecological niche is the particular set of abiotic and biotic conditions and resources upon which an organism or population depends.
True or False?
Two different species can permanently occupy exactly the same ecological niche in the same habitat without any competition.
False.
Only one species can occupy a given niche, so two species attempting to share one will compete until one outcompetes the other.
How do the three North American warbler species that share the same conifer-tree habitat avoid competing with each other?
The warbler species avoid competition by feeding at different heights within the trees, occupying slightly different niches.
occurs when one animal (the predator) eats another animal (the prey).
Predation occurs when one animal (the predator) eats another animal (the prey).
Which pair of species is commonly used as an example of predator-prey population cycles?
The Canadian lynx and snowshoe hare are commonly used as an example of predator-prey population cycles.
Define mutualism.
Mutualism is a relationship between two species in which both species benefit, increasing the carrying capacity of both.
In the mutualistic relationship between bees and flowering plants, what do the plants gain?
Flowering plants gain help with pollination from bees.
Define parasitism.
Parasitism is a relationship in which a parasite benefits from a host organism, while the host does not benefit and is often harmed.
Which vector transmits the parasite that causes malaria in humans?
The mosquito acts as the vector that transmits the parasite that causes malaria.
Competition can be divided into intraspecific competition, between members of the same species, and competition, between members of different species.
Competition can be divided into intraspecific competition, between members of the same species, and interspecific competition, between members of different species.
True or False?
Herbivory can never negatively affect the herbivore population itself, only the plant population.
False.
If herbivory rates are too high, the plant population may decrease too much, which can then also decrease the herbivore population through a negative feedback effect.
Define carrying capacity.
Carrying capacity is the maximum stable population size of a species that an ecosystem can support, determined by competition for limited resources.
True or False?
Humans are the only species whose population size has managed to dominate all other species' populations on Earth.
True.
Humans have overcome many of the limiting factors that would otherwise restrict population growth.
Define density-dependent factors.
Density-dependent factors are factors whose impact on population size varies with the population's density.
Give one example of a density-independent factor that can limit population size.
Climate (e.g. temperature or rainfall patterns) is an example of a density-independent factor that can limit population size.
As population density increases, individuals compete more intensely for limited resources such as food, water and .
As population density increases, individuals compete more intensely for limited resources such as food, water and shelter.
How does higher population density typically affect the risk of predation?
Higher population density typically increases the risk of predation, as predators are more likely to encounter prey.
How does a denser population typically affect the transmission of pathogens?
Dense populations facilitate the spread of pathogens, leading to increased mortality rates.
Define negative feedback mechanism (in the context of population regulation).
A negative feedback mechanism acts to return a population to its equilibrium state, maintaining stability.
Which type of population growth curve is produced when a population grows with unlimited resources?
A J-curve is produced when a population grows with unlimited resources.
Which type of population growth curve is produced when population growth is limited by available resources?
An S-curve is produced when population growth is limited by available resources.
The J-curve has three phases: lag phase, exponential growth phase and phase.
The J-curve has three phases: lag phase, exponential growth phase and crash phase.
The S-curve has four phases: lag phase, exponential growth phase, transitional phase and phase.
The S-curve has four phases: lag phase, exponential growth phase, transitional phase and plateau phase.
True or False?
Once a population reaches the plateau phase of an S-curve, its size remains perfectly constant with no further fluctuation.
False.
The population fluctuates around its carrying capacity, as negative feedback mechanisms respond to changing limiting factors.
Define carrying capacity (as it applies to a population).
Carrying capacity is the maximum population size that an environment can sustainably support, based on the availability of resources.
Which national park is used as an example of how reintroducing a natural predator can help stabilise an ecosystem?
Yellowstone National Park is used as an example, where the reintroduction of wolves helped control the elk population and allowed vegetation to regenerate.
Which mid-20th century agricultural movement significantly increased global food production through high-yield crop varieties and modern techniques?
The Green Revolution significantly increased global food production through high-yield crop varieties and modern techniques.
Clearing forests for agriculture and urbanisation provides more living space and land for food production, which increases human population rates.
Clearing forests for agriculture and urbanisation provides more living space and land for food production, which increases human population growth rates.
True or False?
Environmental degradation has had purely positive effects on human population growth, with no negative consequences for ecosystems.
False.
While environmental degradation has allowed population growth, it also disrupts ecosystems, causing habitat destruction, pollution and resource depletion.
Why is it difficult for the human population to reach a stable equilibrium, in terms of its ecological niche?
Humans have a broad and dynamic ecological niche, constantly adapting through technological innovation and changes in consumption patterns.
How does global trade affect the assessment of human carrying capacity?
Global trade allows societies to access resources from distant locations, complicating the assessment of human carrying capacity.
The development of agriculture and techniques has allowed humans to increase food production and support larger populations than the natural environment could otherwise sustain.
The development of agriculture and irrigation techniques has allowed humans to increase food production and support larger populations than the natural environment could otherwise sustain.
Which social factors can affect human fertility rates and migration patterns, making carrying capacity difficult to predict?
Cultural and social factors can affect human fertility rates and migration patterns, making carrying capacity difficult to predict.
How can urbanised societies with high levels of consumption affect the carrying capacity of their surrounding areas?
Urbanised societies with high consumption can strain the carrying capacity of their surrounding areas due to increased resource demands and waste generation.
True or False?
Estimates of human carrying capacity are generally agreed upon by scientists, with little uncertainty or dispute.
False.
Estimates are often disputed due to uncertainties in factors such as technology, consumption patterns and environmental degradation.
What unique human ability allows people to modify their environment and overcome traditional carrying capacity limitations?
Adaptive capacity allows humans to innovate and modify their environment in response to changing environmental conditions.
Define random sampling.
Random sampling is a method where the position of each sampling point is determined completely by chance, removing researcher bias.
Define systematic sampling.
Systematic sampling is a method where the researcher chooses the position of sampling points using a regular pattern.
True or False?
Systematic sampling completely removes the risk of bias from the person carrying out the sampling.
False.
Systematic sampling can introduce researcher bias, as the person choosing sample points may show bias towards or against certain areas.
When is transect sampling used, rather than random or systematic quadrat sampling?
Transect sampling is used when there is a clear change in physical conditions, such as altitude or light intensity, across the area being studied.
In a belt transect, quadrats are placed at regular intervals along the tape, and the abundance or of each species is recorded within each quadrat.
In a belt transect, quadrats are placed at regular intervals along the tape, and the abundance or percentage cover of each species is recorded within each quadrat.
Define quadrat.
A quadrat is a square frame, commonly 0.25 m² or 1 m², placed on the ground to record the organisms within it.
Which type of organism is most commonly studied using random quadrat sampling to estimate population size?
Non-motile organisms, such as plant species, are most commonly studied using random quadrat sampling.
Which quadrat method is often used when it is difficult to count individual organisms, such as grass or moss?
Percentage cover is often used when it is difficult to count individual organisms, such as grass or moss.
Percentage frequency is calculated as the number of quadrat squares in which a species is present, divided by the total number of quadrat squares, multiplied by .
Percentage frequency is calculated as the number of quadrat squares in which a species is present, divided by the total number of quadrat squares, multiplied by 100.
Which sampling technique is used to estimate the population size of motile (mobile) organisms, rather than quadrats?
The capture-mark-release-recapture technique is used to estimate the population size of motile organisms.
Define Lincoln index.
The Lincoln index is a statistical measure used to estimate the population size of a species, based on the proportion of marked to unmarked individuals recaptured.
In the Lincoln index formula, population size estimate = (M × N) ÷ R, what does M represent?
M represents the number of individuals caught and marked in the first sample.
In the Lincoln index formula, what does R represent?
R represents the number of marked individuals recaptured in the second sample.
True or False?
The capture-mark-release-recapture method assumes that the population stays exactly the same size throughout the study period.
True.
This is one of the key assumptions, and it is often difficult to ensure, since births, deaths and migration can all affect accuracy.
Why must marked individuals be given sufficient time before the second sample is taken in the capture-mark-release-recapture method?
Marked individuals must be given sufficient time to disperse and mix back in fully with the main population before recapture.
Define keystone species.
A keystone species is an organism that has a disproportionately large impact on the structure and function of an ecosystem, relative to its abundance.
Which marine species controls mussel populations along the rocky shores of the North Pacific coast, acting as a keystone species?
The purple sea star (Pisaster ochraceus) controls mussel populations along the rocky shores of the North Pacific coast.
True or False?
Without purple sea stars, mussel populations would remain unchanged and species diversity would stay the same.
False.
Without sea stars, mussel populations would expand rapidly and dominate the ecosystem, reducing overall species diversity.
How do African elephants act as a keystone species in savannah grasslands?
African elephants feed on shrubs and trees, preventing them from dominating the landscape and increasing habitat diversity.
Define biosphere integrity (as one of the planetary boundaries).
Biosphere integrity refers to the overall health and diversity of life on Earth, and is one of the nine planetary boundaries.
What kind of evidence indicates that the planetary boundary for biosphere integrity has already been crossed?
Highly accelerated extinction rates provide evidence that the planetary boundary for biosphere integrity has been crossed.
In a steady-state ecosystem, inputs of energy, nutrients and water are balanced by outputs of energy, nutrients and .
In a steady-state ecosystem, inputs of energy, nutrients and water are balanced by outputs of energy, nutrients and waste.
Which rainforest ecosystem is used as an example of long-term ecological sustainability, having remained stable despite pressures such as deforestation?
The Amazon Rainforest is used as an example of long-term ecological sustainability.
How does deforestation reduce local precipitation in a rainforest ecosystem?
Deforestation reduces transpiration, decreasing the amount of water vapour available for cloud formation and precipitation.
True or False?
Deforestation in the Amazon can trigger a positive feedback loop in which reduced precipitation leads to further forest loss.
True.
Reduced precipitation increases the risk of drought and wildfires, which accelerates further deforestation.
Various conservation strategies can help protect ecosystems, including habitat conservation, species conservation and sustainable management.
Various conservation strategies can help protect ecosystems, including habitat conservation, species conservation and sustainable resource management.
What is the focus of the conservation strategy of habitat conservation?
Habitat conservation focuses on protecting natural habitats from destruction and fragmentation.
What could happen to an ecosystem if human disturbance pushes it past a tipping point?
The ecosystem could shift to a new equilibrium, which may feature different species compositions and reduced biodiversity.
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