12 Biology Data Test Prep

Measuring Biodiversity

Random Sampling - This is where each member of the population is equally likely to be included

You need to use a random number table or random number generator to select numbers

Systemic Sampling - Samples are taken from uniform intervals throughout an area.

Stratified Samping - The process of identifying areas within an overall habitat, which may be very different from each other and which need to be sampled correctly.

Quadrats - Frames of known size that are used to sample vegetation or small organisms in a specific area. They are often used to estimate population density or to study distribution of plants or sessile organims.

Line Transect - A line transect involves laying a straight line through a habitat and counting the organisms that touch or are close to that line to estimate their abundance.

Belt Transect - It involves laying a straight line (transect line) through a habitat and recording all the organisms found within a set width (belt) along that line - for example, 1m wide.

4 ways to Minimise Bias - Size and number of samples

Random Number Generator

Counting Criteria

what is counted in the sample (one leaf presented in one quadrat, is that counted?)

Calibrating Equipment

Percentage Cover - This tells us how much space a species occupies in a particular sample we take.

Percentage Frequency - Is the probability that a species will be found within a single quadrant.

12 Biology Unit 3 Topic 1

Population - The number of a specific species that live in a specific region

Community - Consists of different species living in the same environment / ecosystem

Ecosystem - Is a system formed by living organisms (biotic factors) interacting with one another and their physical environment (abiotic factors).

Biodiversity - The number, variety, and variation of genes, species and ecosystems on earth.

Genetic Diversity - The variety of genes within a species.

Species diversity - The vairiety of different species living in one area (usually an ecosystem).

Ecosystem diversity - This is the variety of different ecosystems in a region / area.

Biological Species Concept - A species is a group of similar organisms that can interbreed in nature to produce fertile offspring and are reproductively isolated from other groups

Biological Species Concept for Asexual Reproduction - Doesn’t work for organisms that reproduce without mating, such as bacteria

Hybridisation - Sometimes, closely related species can produce a viable offspring

Extinct Species - Hard to apply biological species concept since there is no observational data

Ring Species - Each population can breed with its neighbours, but populations at opposite ends can’t breed with each other, even though they’re linked by a chain of interbreeding populations.

Parthenogenesis - Reproduction where males are not needed. Involves Females getting self-fertilised

Things that Limit Biological species concept - Asexual Reproduction

Hybridsation

Extinct Species

Ring Species

Parthenogenesis

Binomial nomenclature - Used to name organisms using their genus and specifc names.

Dichotomous Key - A tool used by biologists to identify and classify organisms based on their characteristics.

Species richness - The number of different species within an area.

Species evenness / relative species abundance - The relative abundance of different species in an area.

Species Diversity (SDI or Simpsons Diversity Index) - Takes into account both the number of species present (richness) and the number of individuals per species (evenness). The closer the value to 1, the higher the diversity.

Assumptions of Lincoln Index - Closed population

All individuals have an equal chance of being caught

Marks are not lost, damaged, or overlooked

Sufficient time for mixing

Sample size is large enough

Biotic Factors affecting population and species diversity in ecosystems - Food availability

Competition for Resources

Predation

Disease

Intraspecific - Competition within the same species for resources

Interspecific - Competition between different species for resources

Abiotic Factors affecting population and biodiversity in an ecosystem - Space

Shelter

Availability of Water

Nutrients

Environmental Conditions like pH, temperature, light levels, etc.

Habitat - The environment of which an organism lives in

Microhabitat - Small, specialised part of a larger habitat.

Distribution of Species - Determined by the habitat patchiness (distribution of resources) and features of the organisms themselves, such as territoriality in animals or autotoxicity in plants.

Uniform Distribution - When individuals are evenly spaced throughout a habitat, often due to competition for resources.

Random Distribution - When individuals are spaced randomly within a specific region with no consistency or specific pattern. This is usually seen in species with an abundance of resources and little interaction between individuals.

Clumped Distribution - When individuals are clustered together, often due to social behaviour, resource availability, or environmental factors.

Law of Tolerance - For each abiotic factor, an organism has a range of tolerances within which it can survive.

Holdridge Life Zone - Classifies global ecosystems (life zones) based on climate factors that determine vegetation type.

Specht Vegetation Classification - Describes vegetation structure in Australia based on plant height and foliage cover

R Strategists - Short life

reproduce quickly before environmental change.

Rapid Growth

allows them to take advantage of resources.

Early maturity

helps reproduce before predators.

Many Offspring

quantity over quality, increased chance of population growth.

Little Parental Care

parents conserve energy for next reproduction cycle.

Pioneers / colonisers

prepare environment for later species to live.

Generalists

survive on wider range of resources and can withstand wider range of conditions

The population is controlled by density independent factors such as climatic events of fires / droughts, etc.

eg: •After rain → puddles form → millions of mosquitoes hatch = population boom.

•When it dries out → puddles evaporate → eggs and larvae die = population crash.

K Strategists - Long life

Slower growth

helps compete for food and territory

Late maturity

help them learn from parents before reproduction

Fewer Offspring

High Parental Care

helps care for young in tough conditions

Later stages of concession

move into environments that are already liveable (not pioneer species)

Niche Specialists

don’t cope well with sudden changes

Population is controlled by density dependant factors (competition / predation, etc).

when too much individuals living in same area increase competition, disease, and predation.

Exponential Growth Pattern - An exponential growth patter (J curve) occurs in an ideal, unlimited environment.

Under ideal conditions with unlimited resources, a population will growth exponentially.

Exponential growth does not happen in natural populations for very long because the resources get used up.

Population growth slows down when food and space become more difficult to find (competition).

12 Biology Unit 3 Topic 2

Trophic Levels - An organisms position in a food chain.

Producers → Primary Consumers → Secondary Consumers → Tertiary Consumers → Quaternary Consumers

How is energy lost between Trophic Levels - Respiration (released as heat)

Movement and activity

Waste (uneaten parts, excretion).

Roles of Decomposers in Ecosystems and Food Chains - Decomposers break down waste to recycle nutrients from the waste for the ecosystem to reuse.

Food Chains - Show the order of trophic level and flow of energy

Food Webs - A complex network of interrelated food chains

Ecological Pyramids - Represent how energy of biomass is distributed across trophic levels.

Why isn’t all sunlight used as energy by plants - Plants can’t absorb all of it since the wavelengths which emit green light would be reflected.

Predation - One organism (the predator) hunts and kills another organism (the prey) for food. (

Competition - Occurs when two or more organisms compete for the same limited resource (e.g. food, water, shelter, mates.).

Mutualism - A relationship where both species benefit.

Commensalism - One species benefits while the other is unaffected (neither harmed nor benefited).

Parasitism - One species (the parasite) benefits while the other (the host) is harmed.

Ecological Niche - The role and space that an organism fills in an ecosystem, including all its interactions with the biotic and abiotic factors in an environment.

Fundamental Niche - All the potential resources that a species can use in its environment.

Requires the absence of competition.

Realised Niche - Some habitats and resources are not available because competitors occupy them.

This is what the species actually uses.

Competitive Exclusion Principle - The exclusion of a species from a community by another organism better adapted to that particular ecological niche.

When one species has even the slightest advantage over another, the one with the advantage will dominate in the long term.

Niche Partitioning - Niche partitioning happens when different species share the same habitat but use it in different ways This reduces competition and allows them to live together.

Keystone Species - A plant or animal that plays a unique and crucial role in the way an ecosystem functions

they have an influence on an ecosystem that is disproportionate to their abundance.

Carrying Capacity - Is the population size that can be supported indefinitely on the available resources and services of that ecosystem.

Limiting Factor - A limiting factor is an abiotic or biotic factor that restricts the number of individuals in a population

because of these limiting factors, each ecosystem has a finite capacity for growth connected to its carrying capacity.

Ecological Succession - The change in structure and species composition of a community over time.

All successions involve changes in structure and function until a climax community (end point of the ecological succession)1 is reached

Pioneer Species - Ability to fixate nitrogen

Tolerance to extreme conditions

Rapid germination of seeds

Ability to photosynthesise efficiently.

Climax Community - Final state of the ecosystem in the stage of ecological succession with little change in species composition and change in ecosystem.

Primary Succession - Ecological succession onto regions that have never been colonised and involves no habitats

Secondary Succession - Refers to reintroduction of organisms (pioneer species) into an ecosystem that may have been destroyed completely and made uninhabitable.

Overexploitation - Harvesting species or resources from the wild at rates faster than natural populations can recover.

Habitat Destruction - Occurs when natural habitats are no longer able to support the species present, resulting in the displacement or destruction of its biodiversity

Monocultures - The agricultural practice of producing or growing a single crop, plant, or livestock species.

Pollution - All forms of pollution (air, water, soil, noise, chemical, etc.) pose a serious threat to biodiversity - they harm living organisms and damage ecosystems.

Holdridge Life Zone - Classifies global ecosystems (life zones) based on climate factors that determine vegetation type.

Specht Vegetation Classification - Describes vegetation structure in Australia based on plant height and foliage cover.