Unit 3 syllabus summary biology

Biodiversity

The diversity of species and ecosystems.

Abundance

Total number of individuals of a species within a specific area.

Density

Number of individuals per unit area or volume.

Lincoln Index (capture-recapture)

A method to estimate population size in large or mobile populations.

DNA Chromosome

A single curled-up chromosome.

Chromosome Pair

Homologous chromosomes inherited from mother and father.

Chromatin

Strands of DNA wrapped around histones inside the nucleus.

Chromatid

One copy of a duplicated chromosome.

Sister Chromatid

The duplicated chromosome attached to its original.

Biosphere

Global ecosystem composed of living (biotic) and non-living (abiotic) factors.

Habitat

The physical living place of an organism.

Population

A group of organisms of the same species living in the same habitat.

Community

Different species of organisms living together in one habitat.

Ecosystem

Interaction between a community and its physical surroundings (biotic + abiotic).

Producers (autotrophs)

Organisms that make organic compounds from inorganic sources (photosynthetic or chemosynthetic).

Consumers (heterotrophs)

Organisms that feed on other organisms to obtain energy.

Detritivores

Consumers that feed on decomposing organic matter.

Decomposers

Organisms (e.g., fungi, bacteria) that break down complex organic matter into simple inorganic molecules.

Species Richness

Number of species present in an ecosystem.

Species Evenness (Relative Abundance)

Distribution of individuals among species in an ecosystem.

Species Abundance

Number of individuals of a particular species in an ecosystem.

Percentage Frequency

Probability of finding a species in a given quadrat.

Percentage Cover

Proportion of an area occupied by a species (useful for immobile organisms).

Simpson’s Diversity Index (SDI)

Measure of biodiversity accounting for both richness and evenness (scale 0–1).

Predation

Interaction where predators consume prey, influencing population density.

Competition

Struggle between organisms for limited resources.

Disease

Transmission more likely in dense populations.

Symbiosis

Long-term interaction between two species.

Mutualism

Symbiotic relationship where both species benefit.

Climate

Temperature, weather, and conditions affecting ecosystems.

Substrate

The surface or medium organisms live on.

Size/Depth of Area

The spatial extent of an ecosystem.

Optimal Range

Conditions under which an organism thrives.

Tolerance Range

Limits of environmental conditions beyond which a species cannot survive.

Taxonomy

Classification of organisms into hierarchical groups.

Binomial Nomenclature

Naming system using genus and species (e.g., Homo sapiens).

Linnaean System

Classification based on physical features and morphology.

K-selected Species

Species with low reproductive rates, long lifespans, and stable populations (e.g., large mammals).

r-selected Species

Species with high reproductive rates, short lifespans, and unstable populations (e.g., insects, algae).

Clade

Group of organisms with a common ancestor and all descendants.

Cladistics

Classification method based on evolutionary ancestry.

Cladogram

Diagram showing evolutionary relationships without scale.

Phylogram

Tree diagram showing evolutionary divergence with scaled branch lengths.

Sexual Reproduction

Involves gamete fusion; offspring genetically different.

Asexual Reproduction

Single parent produces genetically identical offspring.

Phylogenetic Tree

Hypothesis of evolutionary relationships among taxa.

Rooted Tree

Phylogenetic tree with a common ancestor identified.

Unrooted Tree

Phylogenetic tree showing relationships but not a common ancestor.

Biological Species Concept

Species defined by ability to interbreed and produce fertile offspring.

Phylogenetic Species Concept

Species defined by shared evolutionary history.

Interspecific Hybrid (e.g., Mule, Liger)

Hybrid between two species that is usually infertile.

Intraspecific Relationship

Interactions among members of the same species.

Interspecific Relationship

Interactions between different species (predation, competition, etc.).

Terrestrial Community

Land-based ecosystem dependent on vegetation.

Biomes

Large ecological regions with similar climate and conditions.

Vertical Stratification

Different ecological layers within a habitat (e.g., forest canopy, understory).

Ecozones

Large evolutionary regions separated by barriers.

Ecoregions

Subdivisions of ecozones based on vegetation, geology, soil, and climate.

Marine Ecosystem

Ocean-based ecosystem regulating global climate and energy.

Freshwater Ecosystem

Lakes, rivers, and wetlands with low salinity.

Buoyancy

Upward force exerted by fluid, opposing weight of an object.

Holdridge Life Zone System

Global classification of ecosystems based on precipitation, temperature, humidity, and altitude.

Specht’s Classification System

Australian system classifying vegetation based on foliage cover and plant height.

ANAE (Australian National Aquatic Ecosystem Framework)

Classification of aquatic ecosystems in Australia.

EUNIS (European Nature Information System)

Habitat classification system for Europe.

Ecosystem Management

Use of classification and monitoring to conserve ecosystems.

Productive Soils

Soils capable of supporting plant growth and maintaining biodiversity.

Coral Reefs

Marine ecosystems providing coastal protection and biodiversity hotspots; vulnerable to bleaching.

Old-growth Forests

Forests with minimal disturbance, large old trees, understorey, and diverse fauna.

Stratified Sampling

Dividing ecosystems into strata for proportional sampling.

Random Sampling

Every measurement has an equal chance of selection.

Quadrat Sampling

Method to estimate abundance, density, and distribution of species.

Transect Sampling

Line sampling across a habitat to record species distribution.

Mark-Recapture

Technique to estimate population size using captured and marked individuals.

Lincoln Index Formula

N = (M × n) / m, where M = first marked sample, n = second sample, m = marked recaptured.

Water Cycle

Evaporation, condensation, precipitation, and transpiration cycling water.

Carbon Cycle

Movement of carbon through photosynthesis, respiration, decomposition, and fossil storage.

Nitrogen Cycle

Transformation of nitrogen through fixation, nitrification, and denitrification.

Nitrogen Fixation

Conversion of atmospheric N₂ into ammonia usable by plants.

Nitrifying Bacteria

Convert ammonia into nitrites and nitrates.

Denitrifying Bacteria

Convert nitrates back into nitrogen gas.

Ecological Niche

The role and function of an organism in an ecosystem, including habitat, feeding, and interactions.

Fundamental Niche

Theoretical full range of conditions a species can occupy.

Realised Niche

Actual conditions occupied due to competition and constraints.

Competitive Exclusion Principle

Two species cannot occupy the exact same niche indefinitely.

Keystone Species

Species with disproportionate effects on ecosystem stability and diversity.