Biology Unit One

Biodiversity

the variety of life in the world or in a particular habitat or ecosystem.

Endemism

species that occur in only one particular geographical location.

Genetic Biodiversity

the variations within a species that is mainly due to the number of alleles or genes within the population.

Low genetic biodiversity means...

an organism reduces its ability to adapt to a changing environment.

High genetic diversity means...

an organism increases its ability to adapt to a changing environment.

Two criteria for biodiversity hotspot

- minimum of 1,500 species of endemic native vascular plants
- lost 70% of primary native vegetation
e.g. Great Barrier Reef, Southwest WA

Species Biodiversity

the number of different species within an ecosystem.

species with high species diversity are called...

megadiverse

Megadiversity is measured...

by the total number of species in a country and the number of endemic species.

Ecosystem Biodiversity

the number of different types of naturally occurring ecosystems within an area.

5 reasons why we classify organisms:

- communication between scientists is more accurate and precise
- allows quick, accurate description of an organism
- assists in identification of an unknown organism
- shows trends in the development within a group
- shows evolution from simple to complex structures

Biological Species Concept

a species is a group of individuals that can breed and produce viable and fertile offspring.

Morphological Species Concept

a group of individuals that have similar characteristics is the same species.

Phylogenetic Species Concept

the smallest group of individuals that share a common ancestor and usually have very similar DNA.

who invented the Binomial System?

Carl Linnaeus

Levels of Classification

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.

Eukaryotes contain...

DNA within a nucleus and membrane bound organelles.

Prokaryotes contain...

no nucleus or membrane bound organelles.

List the three domains

Eukarya, Archaea, Bacteria

List the six kingdoms

1. Archaea
2. Eubacteria
3. Protista
4. Fungi
5. Plantae
6. Animalia

Animalia includes...

mammals, insects, and sea sponges

Plantae includes...

mosses, flowering plants, and trees

Protista includes...

amoebae

Fungi includes...

yeasts, molds, mushrooms

Archaea includes...

microscopic, single celled organisms known for living in extreme environments.

Bacteria includes...

microscopic, single celled organisms

Physical Classifications Examples

- body symmetry (bilateral, radial)
- tissue layers (germ, endoderm, mesoderm, ectoderm)
- body cavity (caecum {species digestive system}, musculoskeletal system, placenta vs pouch)

Reproductive Methods

- sexual
- asexual

Molecular Sequences

- DNA sequences protein
- amino acids
- proteins

Dichotomous Key

a key for the identification of organisms based on a series of choices between alternative characters

Cladistics (phylogenetics)

a type of classification based on physical characteristics and/or molecular sequences.

Systematics is the study of...

relationships between species

Phylogenetic Tree (cladogram) is a...

graphical representation of species and their relationship.

Clade

a group of species from one branch.

Node

formation of a new species (evolution of new species).

List types of Ecological Relationships

interspecific, intraspecific, predator-prey

Interspecific

a type of competition where individuals of different species compete for the same resource in an ecosystem.

Intraspecific

a type of competition where individuals of the same species compete for the same resources in an ecosystem.

Predator-Prey

relationships are cyclic with a lag phase and depend on each other.
- as prey population maximises, predator population begins to increase.
- as prey population declines, there is a lag phase for predator populations to decrease.

Disease

the host numbers may be reduced to the extent that resources are free for other competitors.

Symbiotic Relationship: Parasitism

one species benefits at the expense of another.
e.g. leach, tick, mosquito

Symbiotic Relationship: Mutualism

both species in the relationship benefit and neither is harmed
e.g. bee, clownfish

Symbiotic Relationship: Commensalism

one species benefit and the other neither benefits nor is harmed.
e.g. shark, cow

Keystone Species

a species that influences the survival of many other species in an ecosystem, prevents any organism in the lower trophic levels from monopolising food, resources, and space, and allows for richer biodiversity within a restricted area.
e.g. southern cassowary: 70-100 species of rainforest plant species depend on the cassowary to disperse seeds.

Sources of Life

- the sun provides radiant energy, visible light, non-visible radiation, and heat
- heat from the Earth's core supplies thermal energy to support organisms in regions where conditions are extreme

How do organisms use energy?

- autotrophs (producers)
: converts light energy to chemical energy by photosynthesis.
: produce all of the organic matter, or food, for all other organisms in an ecosystem.
- heterotrophs (consumers)
: depend on autotrophs directly or indirectly for their energy needs and their supply of matter.
: consume other organisms.
: can be herbivores, carnivores or omnivores.

Photosynthetic Efficiency

the fraction of light energy that plants and algae convert into chemical energy during photosynthesis.

Gross Primary Productivity

the total organic matter in an ecosystem made by photosynthesis.

Net Primary Productivity

the amount of organic matter actually available to herbivores.

Food Chains

linear models that show the transfer of matter and energy in an ecosystem.
each feeding level/stage in the food chain is called a trophic level.

Trophic Level: producers

always begin with producers as they convert light energy into chemical energy.
e.g. plants, autotrophs

Trophic Level: consumers

require chemical energy and nutrients to make organic molecules.
e.g. herbivores, carnivores

Energy is important for...

- photosynthesis
- cellular respiration

Energy loss (trophic efficiency)

- 10% of energy at one trophic level is passed onto the next level.
- 90% of energy is lost to the surroundings as heat and chemical energy in wastes.

Modelling Ecological Systems: Photosynthesis

CO2 + H20 (inputs) --\> photosynthesis (processing) --\> O2 + glucose + H20 (outputs + storage)

the loss of energy at each link limits the number of trophic levels a food chain can have (maximum of 6).

Measuring Trophic Efficiency

kJ/m-2/y-1 (kilojoules per square meter per year)

Niche

an organism's particular role in an ecosystem, or how it makes its living.

Realised Niche

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

Ecological Niche

the way a species function within its environment
e.g. when and where a species eats, sleeps and mates.

Fundamental Niche

the potential region an organism could inhabit if there were no predators, competitors or parasites.

Competitive Exclusion Principle

states that two similar species that compete for a resource cannot coexist in the same community.
organisms cannot feed on the same food sources at the same time.
adaptions (food sources, use of space, timing of activities) reduce their competition.

Food Webs

interconnecting food chains in an ecosystem.

Pyramid of Numbers

representation of the number of individual organisms in each trophic level of an ecosystem.
shows the progressive fall in numbers at each level.

Inverted Pyramid of Numbers

results when a communities contain parasites.

Pyramid of Biomass

a pyramid that illustrates the total mass of all the organisms in a trophic level.
measurement can be shown as a rate or data from a particular time.
e.g. g/ms-2/year-1

Inverted Pyramid of Biomass

can occur during certain times of the year when organisms with short life cycles breed rapidly to have more biomass.
e.g. zooplankton

Pyramid of Energy

a pyramid that shows the total amount of energy available at each trophic level.
expressed in units of energy per area at a given time.
e.g. kJ/m-2/y-1
NEVER INVERTED!

Energy is needed for...

- growth and repair of organisms
- reproduction

Energy is lost along food chains by...

- cellular respiration
- faeces and dead tissue

Detritivores

feed on dead and decaying organic remains and wastes.
e.g. faeces, dead tissues
--\> e.g. earthworms, yabbies, dung beetles

Decomposers

break down complex molecules of organic matter/material in or on where they live.
e.g. fungi, some bacteria

Time taken to recycle depends on...

- abiotic factors (humidity, soil moisture, rainfall)
- biotic factors (amount of organic material, types of leaves {thin/soft})

Tropic areas decompose...

fast as leaves only take a few months and logs only take a few years.

Eucalypt Woodlands decompose...

slowly as leaves take a few years and logs take a few decades.

Arid Environments decompose...

slowly as leaves take a few decades and logs take at least half a century.

Carbon Cycle

the organic circulation of carbon from the atmosphere into organisms and back again.

Carbon Cycle: Sink

a region on Earth where carbon deposits accumulate.
e.g. fossil fuels, ocean, vegetation, trees are sinks when they're alive but sources when burnt.

Carbon Cycle: Source

areas on Earth where carbon is released.
e.g. origin of carbon deposits in sinks, trees are sinks when they're alive but sources when burnt.

Respiration

releases CO2 from organisms into the air.

Photosynthesis

stores CO2 from the air into organic matter (trees).

Decomposition

releases carbon from dead/decaying organisms into the air.

Combustion

releases carbon from organisms, when burnt, into the air.

Nitrogen Cycle

the transfer of nitrogen from the atmosphere to the soil, to living organisms, and back to the atmosphere.

Fossilisation

stores carbon from organisms into hydrocarbons (oil, gas, coal).

Nitrifiers

convert decaying material into nitrites.
- bacteria: convert ammonia to urine to faeces, and dead plants and animals to nitrite ions (NO2-).
- other bacteria: convert nitrites to nitrates that only can be absorbed by plants.

Denitrifiers

convert nitrites to atmospheric nitrogen.
- plants growing in waterlogged areas have a shortage of O2.
- bacteria: convert nitrates in the soil to nitrites. this releases O2 required for their metabolic processes.

Population

a group of individuals that belong to the same species and live in the same area at the same time.

Types of Populations

- clumped (termites, herds of animals, schools of fish)
- uniform (penguin colonies)
- random (shark, tiger, eagle)

Types of Population Growth

exponential and logistic

Stages of Population Growth

1. slow growth (few individuals)
2. exponential growth (abundant resources)
3. deceleration (limited resources)
4. plateau (carrying capacity)

Carrying Capacity

largest number of individuals of a population that a environment can support

Factors that Affect Population Growth

- density dependent (BIOTIC: competition, disease, predation, food availability)
- density independent (ABIOTIC: temperature, fire, drought, flood)

Controlling Populations: Biological Control Agents

- general predators: organisms that consume a great variety of species (ladybugs, caterpillars, mites)
- specialised predator: organisms that target one pest species (dragonflies target mosquitoes)
- parasites: an organism that benefits at the cost of another species (wasps lay their eggs in the bodies of hosts, leading to host's death)
- microbial diseases: caused by bacteria, fungi and viruses that target species and causes one's death.

Controlling Populations: Physical Control Agents

- culling: the reduction in abundance of a species that is pushing the ecosystem beyond its carrying capacity. it must be done humanely, and it ensures sustainability of ecosystems and viability of native (foxes, wild cats and dogs, dingoes, rabbits)

Controlling Populations: Chemical Control Agents

- chemical pesticides: controls pest species as they are quick and effective.
(1080 (sodium fluoroacetate) --\> fox and cat baits)
(herbicide (glyphosate) --\> weed species)

Fire Stick Farming led to... moved... creates a...

- led to deflected succession
- moved grassland ecosystems
- creates a mosaic of various shapes of succession

Fire Adaptations

- nutrients being released back into the soil
- lignotubers prevent the plant from being destroyed
- thick bark protects vascular tissue from fire damage
- epicormic buds are stimulated to grow when leaf tissue is destroyed
- flower stimulation in species like grass trees
- seed germination when exposed to compounds from smoke
- nuts (seed coverings) are opened when exposed to heat from fire

Primary Succession

type of succession that occurs in an area in which no trace of a previous community is present.
begins with rock and pioneer species begin to colonise the rock.

Secondary Succession

type of succession that occurs in an area that was only partially destroyed by disturbances.
soil starts to form as pioneer species die and rock is being broken down.
weed species begin to colonise the rock and organic matter increases.

Intermediate Changes

as more plants die, organic matter and soil depth increases. plant diversity increases and animals begin to colonise habitat and increase biodiversity.