QCAA Biology: Unit 3

Taxonomy

The scientific study of how living things are classified.

Clade

A group of organisms that consists of a
common ancestor and all its lineal descendants.

Biodiversity

Biological diversity; the variety of
all life forms, the genes that they contain and
the ecosystems of which they are a part.

Ecosystem

A system formed by living organisms
interacting with one another and with their
physical environment.

Ecological Niche

The role and space an
organism fills in an ecosystem, including all its
interactions with the biotic and abiotic factors
of its environment. The part where the species is most likely to survive, reproduce and persist indefinitely.

Keystone Species

A plant or animal that plays a
unique and crucial role in the way an ecosystem
functions. eg. cassowary, wolves, whales

Carrying Capacity

The size of
population that can be supported indefinitely
on the available resources and services of that
ecosystem.

Succession

The process of gradual changes
in an ecological community over a period
of time. These changes are orderly and
generally predictable in the absence of major
disturbances.

Primary Succession

The series of changes
in community composition that develops
over time on newly formed terrain that has
previously been uninhabited by living things,
such as newly made volcanic rock.

Secondary Succession

The series of changes
in community composition that develops
over time on terrain that has previously been
inhabited by living things but which has
suffered disturbance, such as fire or clearance
by humans.

Parthogenesis

Growth and development of an embryo that has not been fertilised/ virgin birth.

External Fertilisation

Union of gametes which occurs outside the female's body and is typical in aquatic animals, amphibians and some insects.

Internal Fertilisation

Fusion of gametes which occurs inside the body of the female or hermaphrodite and is typical of most terrestrial animals and some fish.

R-strategist

Reproductive strategy in which organisms reproduce early, bear many small, unprotected offspring (ex. insects, mice).

K-strategist

Reproductive strategy in which organisms reproduce late, bear few, cared for offspring (ex. humans, elephants).

Molecular Phylogeny

Branch of phylogeny that analyses genetic, hereditary, hereditary molecular differences predominantly in DNA sequences, to gain information on an organism's evolutionary relationships.

Predation

The consuming of one organism by another.

Competition

Compete for mates, nest sites, food or space. May be intra or interspecific.

Intraspecific Competition

Competition among members of the same species.

Interspecific Competition

Competition between members of different species.

Symbiosis

Loose association between animals.

Mutualism

A relationship between two species in which both species benefit.

Obligate Mutualism

Mutualism in which at least one species can't survive without its partner. eg. ants and the Acacia plant

Facultative Mutualism

Mutualism in which both species can survive alone. eg. Bees and plants

Commensalism

A relationship between two organisms in which one organism benefits and the other is unaffected. eg. Cow + bird

Amensalism

A relationship in which one organism is harmed and the other is unaffected. eg. Algal blooms

Parasitism

A relationship between two organisms of different species where one benefits and the other is harmed. e.g. Tick on a dog

Foliage Cover

Measure of a vertical projection of exposed leaf area. Cover is equal to the shadow cast if the sun was directly overhead.

Habitat

The environment where an organism or species lives, grows and reproduces.

Ecosystem

A system formed by living organisms interacting with one another and with their physical environment.

Ecosystems

A system composed of various habitats, ranging in size from a microhabitat to an ecoregion.

Microhabitat

A small, particular part of a habitat in which particular organisms live; for example, beneath the bark of a tree within a forest habitat or a singular RBC.

Ecoregion

Large region of the Earth's surface generally containing similar ecosystems.

Common Ancestry

An organism exists from which two or more species diverge.

Bifurcation

Two way splitting of a branch.

Physical Change

As mutations accumulate in populations physical changes will occur in the population. As time increases more mutations accumulate and more physical changes accumulate.

Phylogenetic Tree/Phylograms

A branching diagram that represents a hypothesis about the evolutionary history of a group of organisms (branch length shows evolution).

Cladograms

A branching diagram showing the cladistic relationship between a number of species (branch length is unscaled.)

Stratified Sampling

Sampling technique where the study area or population is divided into strata or subgroups. Systematic or random is then applied to each stratum, can be vertical or horizontal.

Systematic Sampling

Sampling technique where samples from a larger population are selected according to a random starting point and a fixed periodic sampling interval.

Random Sampling

Sampling technique which is a fair (unbiased) representation of organisms in the population and their distribution.

Non-random Sampling (Opportunistic Sampling)

Sampling technique where subjects are selected as they are easily accessible.

Mark and Recapture

Sampling technique where organisms are captured and marked, then recaptured to count how many are marked.

Genetic Diversity

The range of genetic material present in a gene pool or population of a species.

Species Diversity

The number and relative abundance of species in a biological community.

Ecosystem Diversity

Variety of habitats, living communities, and ecological processes in the living world.

Biome

Group of ecosystems that have the same climate and dominant communities.

Species Richness

A simple tally of the number of species within a particular area.

Species Abundance

The number of individuals of a particular species in the ecosystem.

Species Evenness

A measure of the number of individuals of that particular species in relation to the total number of individuals of all species in the area.

Percentage Cover

An estimate of the percentage of each quadratic covered by a particular species, can involve the quartet being divided into smaller squares and require agreement on how to count squares. Can be basal cover, ground cover, leaf cover or canopy cover.

Percentage Frequency

Measure of the appearance of a plant species within sample quadrats.

Simpson's Diversity Index

A measure of species diversity that considers both richness and evenness.
1- n(n-1)/N(N-1)

Physical Factors

Category of factors which include temperature soil composition, rainfall patterns, altitude, pressure, soil composition, light penetration and pH.

Biotic Factors

Category of factors that are living or produced by living things eg. food sources, predators, pathogens and impact of human activities.

Chemical Factors

Category of factors which include the pH of the soil/water and salinity levels.

Dynamic Factors

Category of factors which include wind speed and pattern and wave action.

Autotrophs (producers)

Organisms that synthesise their own complex organic molecules using simple substances like carbon dioxide and water.

Chemosynthetic Autotrophs

Autotrophs that obtain energy from carbon fixation from inorganic chemical reactions in a process known as chemosynthesis.

Photosynthetic Autotrophs

Organisms that use sunlight to produce their own food. eg. plants

Heterotrophs (consumers)

Organisms that obtain their nutritional and energy requirements by consuming other living things or their products.

Detritivores

Organisms which consume small particles of dead matter and organic waste. e.g.. earth worms

Decomposers

Organisms that secrete digestive enzymes which break down wastes and dead organisms and return raw materials to the environment.

Biomass

Measure of the total quantity of biological matter (dry weight) of a group of organisms in a given area.

Productivity

The rate of generation of biomass in an ecosystem (kgm^-2day-1).

Food Chain

A series of events in which one organism eats another and obtains energy.

Food Web

A system of interlocking and interdependent food chains.

Photosynthesis

A multi-step pathway involving a series of enzyme and chemical reactions and is summaries by the equation: 6CO2 + 12H20 -> C6H12O6 + 6O2 +6H20.

Chemosynthesis

Process by which ATP is synthesised by using chemicals as an energy source instead of light.

Trophic Level

Each of several hierarchical levels in an ecosystem, comprising organisms that share the same function in the food chain and the same nutritional relationship to the primary sources of energy.

Ecological Pyramid

Illustration of the relative amounts of energy or matter contained within each trophic level in a given food chain or food web.

Gross Primary Production (GPP)

The total quantity of chemical energy stored in plant biomass, in a given area or volume.

Net Primary Production (NPP)

The chemical energy stored in plant biomass after respiratory losses to the environment have been taken into account.

Gause's Law of Competitive Exclusion

Two species living in the same ecosystem at the same time will not have exactly the same niche. If they do, one species will outcompete the other to extinction.

Niche Partitioning/Differentiation

The formation of realised niches that do not overlap, allowing both species to coexist as they are not competing for resources.

Fundamental Niche

The full potential range of the physical, chemical, and biological factors a species can use if there is no competition from other species.

Realised Niche

The actual conditions and resources in which a species exists due to biotic interactions.

Trophic Cascade

A series of changes in the population sizes of organisms at different trophic levels in a food chain, occurring when predators at high trophic levels indirectly promote populations of organisms at low trophic levels by keeping species at intermediate trophic levels in check.

Distribution

The geographic range over which the individuals in the population live.

Abundance

The actual number of individuals in the population.

Tolerance Range

Environmental conditions in which an organism can survive.

Limiting Factor

A factor that acts on a population to slow its growth (biotic or abiotic).

Density-dependent Factors

A factor that influences population size and density, but magnitude of effect depends on the existing population density (eg. predation, crowding, parasitism, disease.)

Density-independent Factors

A factor that impacts a population regardless of population size or density (environmental temperature, intensity of sunlight, pH of soil and water, salinity, natural disasters).

Natality

The ratio of the number of births to the size of the population; birth rate.

Mortality

The ratio of the number of deaths to the size of the population; death rate.

Immigration

Movement of individuals into a population.

Emigration

The movement of individuals out of a population and into another population.

Lincoln Index

A method for determining population size by marking and recapturing portions of a population.
N= Mxn/m

Exponential Growth (J curve)

Growth pattern which occurs when environmental conditions are favourable and resources are not limiting. If favourable conditions continue (no limiting factors) can result in population explosion.

Population Crash

Dieback of a population which occurs when the number of individuals exceeds the carrying capacity; suddenly limited resources resources which results in a rapid population decline.

Logistic Growth (S curve)

Growth pattern in which a population's growth rate grows exponentially initially before flattening out as growth is affected by density-dependent factors. Growth may decline until birth and death rates are balanced.

Dynamic Carrying Capacity

Carrying capacity which varies depending on fluctuation in environmental conditions eg. weather, climate change, competitors, water availability.

Equilibrium

Balanced state where a population becomes relatively constant and births and deaths cancel each other out.

Population Explosion

A sudden increase or burst in the population in either a certain geographical area or worldwide.

Ecological Succession

The process through which a natural community of plants and animals changes after a disturbance and is typically classified as either primary or secondary succession.

Pioneer Community

First integrated set of plants, animals, and decomposers found in an area undergoing primary ecological succession; first sere.

Climax Community

A stable, mature community that undergoes little or no change in species over time.

Zonation

The arrangement or patterning of plant communities or ecosystems into parallel or sub- parallel bands in response to change, over a distance, in some environmental factor.

Primary Succession

An ecological succession that begins in an area where no biotic community previously existed.