What term describes all the populations of different species living and interacting in the same area?
Community
A community includes all populations of different species within a defined area.
What is the term for a biological community together with the non-living components of its environment?
Ecosystem
Ecosystems include both biotic (living) and abiotic (non-living) components.
Within a habitat, what term describes the role of a species including how it uses resources and interacts with other organisms?
Niche
A niche includes feeding relationships, habitat use, and interactions with abiotic factors.
What is the name for the maximum population size of a species that an ecosystem can support over time?
Carrying capacity
Determined by resource availability and environmental conditions.
True or False:
Carrying capacity for a population in an ecosystem always remains constant.
False
Carrying capacity can fluctuate due to environmental changes and species interactions.
What type of competition occurs between individuals of different species for the same resources?
Interspecific competition
Occurs when species share limited resources such as food, space or light.
What type of competition occurs between individuals of the same species?
Intraspecific competition
Often intense because individuals require identical resources.
What interaction occurs when one organism kills and consumes another organism?
Predation
Predator–prey relationships influence population sizes.
Which sampling method uses randomly placed square frames to estimate the abundance of slow-moving or non-motile organisms?
Quadrats
Often used to estimate plant abundance or sessile animals.
What type of transect involves placing quadrats at regular intervals along a line across a habitat?
Belt transect
Used to investigate how species distribution changes across environmental gradients.
Which method estimates the population size of motile organisms by capturing, marking, releasing, and recapturing individuals?
Mark-release-recapture
Often used for animals that move freely within a habitat.
Fill in the blanks:
In the mark-release-recapture method, population size is estimated using the formula: population ≈ (number first captured × number second captured) ÷ number of ______ ______ ______.
marked individuals recaptured
Population = (n₁ × n₂) ÷ m₂
Assumes mixing of individuals between sampling events.
True or False:
In mark-release-recapture studies, marked individuals must mix randomly back into the population before recapture.
True
This assumption ensures a representative sample in the second capture.
What ecological process describes the gradual change in species composition of a community over time?
Succession
Can occur after disturbance or on newly formed habitats.
What type of succession begins on newly formed or previously uninhabited land with no soil present?
Primary succession
Examples include volcanic rock or glacial retreat areas.
What organisms are the first to colonise bare surfaces during primary succession?
Pioneer species
Typically hardy species such as lichens or mosses.
What term describes the relatively stable final stage of ecological succession?
Climax community
Species composition remains relatively constant unless disturbed.
True or False:
Pioneer species often modify the environment in ways that allow other species to colonise.
True
They may build soil, add nutrients, or alter moisture levels.
How can organisms involved in succession alter abiotic conditions to support greater biodiversity?
Reduce environmental hostility.
Examples include increasing soil depth, nutrients, and moisture retention.
Why is succession sometimes actively controlled in conservation areas?
To manage succession
Prevents habitats changing into later stages that may reduce target species.
Why must conservation often balance environmental protection with human requirements?
Sustainability
Sustainable management ensures natural resources remain available long term.
What practical investigation studies how an environmental factor affects where a species occurs?
Distribution investigation
AQA Required Practical 12 investigates species distribution relative to a factor.
When studying sessile organisms with quadrats, what two measurements can be used to estimate abundance?
Percentage cover and frequency
Percentage cover estimates area occupied; frequency measures presence in quadrats.
True or False:
Belt transects are particularly useful for studying changes in species distribution across environmental gradients.
True
They reveal patterns along changes such as moisture, altitude or light.
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1: Biological Molecules138
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1: Enzymes & Digestion16
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1: Cell Structure52
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1: Cell Division20
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1: Membranes & Transport20
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2: Exchange & Transport Systems76
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2: Plant Transport20
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2: Immunology36
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3: DNA & Protein Synthesis27
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3: Genetic Diversity14
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3: Biodiversity & Classification32
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3: Investigating Diversity12
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4: Evolution42
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4: Populations & Ecosystems24
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4: Energy & Nutrient Cycles35
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5: Photosynthesis23
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5: Respiration17
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5: ATP & Energy Transfer11
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6: Homeostasis57
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6: Nervous Coordination53
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6: Stimuli & Response62
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6: Muscles14
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7: Inheritance12
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7: Populations (Hardy–Weinberg)15
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8: Gene Mutations & Expression58
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8: Gene Technologies46
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8: Disease24
