Year 12 Biology

Why conserve?• Reasons why organisms are under threatHuman impact – • habitat destruction – clearing for farms, houses, mines• hunting• pollution• introduced species (competition & predation)

• Reasons for conservationAesthetic value of biodiversityEthics – is it right to destroy biodiversity?Custodial – we should preserve biodiversity for future generationsUtility – biodiversity may provide useful products (e.g. medicines)Ecosystem stability – biodiversity contributes to ecosystem servicesRecreation/ecotourismScientific researchEducationBetter ability to cope with environmental change/greater genetic diversity

Levels of threatStatus Degree of threat Examples

Near threatened

(Rare)

Low numbers – may qualify as threatened without conservation measures

Red-tailed black cockatoo, Koala, Jarrah, Squirrel glider, Rothschild’s giraffe, White rhino, Spotted hyena

Threatened -

Vulnerable

High risk of extinction Baudin’s cockatoo, Numbat, Quokka, Bilby, Tiger quoll, Chuditch, Western ringtail possum, Ghost bat, Kowari, Southern cassowary, Cheetah, Ring tailed lemur, Lion

Threatened -

Endangered

Very high risk of extinction Carnaby’s cockatoo, Woma, Dibbler, Sandhill dunnart, African painted dog, Radiated tortoise, Black & white ruffed lemur, Asian elephant, Red panda, Galapagos tortoise

Threatened -

Critically endangered

Extremely high risk of extinction

Western swamp tortoise, Silvery gibbon, Orang utan, Sumatran tiger

Extinct Not been seen for 50 years – presumed species no longer exists

Dodo, passenger pigeon, Tasmanian tiger

Role of organizations in conservation strategies

Organization Examples Roles

Zoos Perth zoo Education, captive breeding, preservation of genetic material, research

National parks or reserves Kakadu Habitat & breeding sites

Government agencies CALM, CSIRO Management, research, policing

Local groups Friends of Bennett brook

Local habitat preservation, replanting of natives, rubbish & pollution control

School programs Ribbons of Blue, Airwatch

Education, local conservation programs – monitoring, replanting

Biological control• How it works an organism is found that acts as a control agent – usually

predator or disease• Examples • Cactoblastis moth eats prickly pear• Calicivirus/myxomatosis kills rabbits• Lady birds & wasps eat insect pests (eg aphids, mealy worm)• Dung beetle disposes of cattle dung so there is nowhere for blowflies to lay

eggs• Irradiated (sterile) male fruit flies released to breed with females no

offspring• Benefits• Once in place no need for further human intervention – its self regulating• It reduces use of poisons• Knowledge needed for effective useThe control agent must not be able to become a pest itself:It is specific & won’t harm anything else, it won’t introduce a disease, it dies out

when the food source dies out & it won’t hybridize with native organisms

Captive breeding programs

• How it works Animals are bred in captivity (zoos or parks), then may be released back into the wild, or

into reserves or parks. This may involve artificial insemination, in vitro fertilisation and or hand rearing of offspring

Plants may be produced by tissue culture, cuttings or seed. Seed banks may store seed to maintain genetic diversity

• Examples Numbats, chuditch, western swamp tortoise are bred then released into managed

reserves (fenced areas where baiting programs have removed introduced predators eg foxes & cats)

Other species bred at the Perth zoo include orang utan, gibbon, rhinoPlants – Wollemi pine (ancient remnant of pines found in the Blue mountains –

propagated by tissue culture, Jarrah resistant to dieback being propagated by seed and tissue culture

• BenefitsMaintains existence & genetic diversity of species under threat in natural habitats• Knowledge needed for effective useReproductive technology (eg AI, IVF, tissue culture)Life cycle & breeding habits of species involved (eg apes must be taught how to raise

young by seeing mothers or sisters doing it) , Symbiotic associations (eg orchids have a mutualistic relationship with fungi, Australian

Christmas trees are semi parasitic on wattles, callistemons or eucalypts)

Conservation of wilderness areas/national parks

• How it works set aside areas which are not cleared & human access is managed –eg some areas closed to humans, others restricted access

• Examples Kakadu, Ningaloo reef, Great barrier reef, John Forrest National Park

• Benefits preserves habitats & threatened species• Knowledge needed for effective useEcological importance of protected area – numbers & types of

threatened species presentLifecycle &habits of protected species – area must be sufficient to

provide enough space, nesting/breeding spots and food for the species to be conserved

Reafforestation

• How it works planting of trees/shrubs & other plants• Examples Planting to reclaim areas affected by salt or erosionReplanting after miningRestoring native bushland along roads and paddocks to provide a bush corridorReplanting along drains and swamps to repair damage of human impactReplanting to absorb carbon dioxide• BenefitsProvides habitat, food & shelter for native animalsHelps repair damaged areas (eg salt affected, eroded areas)Bush corridors allow small animals to move in safety – allows a larger area for foraging &

connects small isolated populations increase genetic diversityAbsorbs carbon dioxide & reduces pollution• Knowledge needed for effective useSpecies originally present – so replanting is as close to the original as possibleSpecies that are salt tolerantPreferred food sources/habitat for animal species you’re trying to attractPropagation/germination techniques – eg many species need fire to germinateSymbiotic associations (eg orchids have a mutualistic relationship with fungi, sandal wood &

Australian Christmas trees are semi parasitic on wattles, callistemons or eucalypts)

Management of fishing and hunting eg bag limits, size limits, licensing

• How it works limits are set on the numbers and/or size of animals being fished/hunted. Animals may only be hunted at certain times of the year

• Examples Abalone can only be collected for a very short period, and only a few per fisherFish, crayfish & prawns have minimum legal sizes – undersize animals must be

returnedFemale crayfish & prawns with roe (eggs) must be returnedCommercial fishermen must be licensed – this allows control of how much is

takenCertain areas are set aside as non-fishing/hunting areas – this protects breeding

grounds• BenefitsLimits numbers taken to that of the population presentProtects breeding grounds, youngsters & breeding females• Knowledge needed for effective usePopulation numbers presentLifecycle & breeding information eg many fish species start male & become

female as they age (get larger) – if all the larger fish are taken, there may not be enough females to breed from

Development of new strains of crops/food animals• How it works new strains of high yield or disease/pest resistant

crops/food animals are bred or genetically engineered• Examples Higher yield hybrid cereals eg rice, wheatCereals that tolerate lower rainfall or salinity eg wheatDisease resistant crops eg wheat that resists rustPest resistance – either by breeding or by inserting DNA eg GM canola

& cotton Pigs and chickens that grow faster, so take less time to reach

marketable size• BenefitsFarms produce more food, more quicklyFarmers can use areas that are dry or saline to produce cropsFarmers can use less pesticide• Knowledge needed for effective useLifecycles, physiology & genetic techniques

Short answer 2004 a & bEuropean settlement in Australia has had a range of harmful effects on

the environment. Widespread clearing of land for agricultural purposes has had a serious impact.

a) Name four environmentally harmful effects of widespread land clearing.

Introduced species are another major problem that came with European settlement. Grasses and other weeds have escaped from farms to establish themselves in bushland.

b) Briefly explain two different ways these non-native plants can harm natural ecosystems.

Short answer 2004 a & bEuropean settlement in Australia has had a range of harmful effects on the environment. Widespread

clearing of land for agricultural purposes has had a serious impact. a) Name four environmentally harmful effects of widespread land clearing.Increased/changed salinityIncreased soil erosion/increased runoffDecreased soil fertilityLoss of animal habitatLoss of biodiversityEasy access for introduced speciesClimate changeDesertificationRising water table/waterlogging/increased floodingNamed effect on a neighbouring ecosystem1 mark each to maximum of 4Introduced species are another major problem that came with European settlement. Grasses and other

weeds have escaped from farms to establish themselves in bushland. b) Briefly explain two different ways these non-native plants can harm natural ecosystems. Out-compete native species, leading to loss of biodiversityNative animals die when their food plants are excludedMay be a food source for introduced speciesChanges to fire behaviour, so fires may be more or less frequentMay be toxic to some native species, hence decline in numbersAn example will be accepted instead of an explanation. e.g., outcompete native speciessuch as bridal creeper smothering native vegetationMay introduce disease and transmit to native vegetation2 marks/line, maximum 4

Short answer 2004 c(c) To combat introduced pests, scientists sometimes use a strategy

called biological control. i) Briefly explain what is meant by biological control.

ii) List three precautions that must be taken to ensure biological control does not get out of control itself.

Short answer 2004 c

(c) To combat introduced pests, scientists sometimes use a strategy called biological control.

i) Briefly explain what is meant by biological control. Introduction of a natural enemy (predator, parasite, disease) to control pest

numbers

ii) List three precautions that must be taken to ensure biological control does not get out of control itself.

The control must be specific

The control must not introduce a disease

The control must not be able to become a pest itself

The control dies out when the food source dies out

The control will not hybridize with native organisms

Short answer 2004 d & eAnother problem is caused by the fertilisers used in agriculture and

gardens. In particular, phosphate fertiliser can kill native plants that require little phosphate and it also causes toxic algal blooms in waterways. Part of the problem is caused by the fact that roadside drains in urban areas drain into waterways, carrying with them anything that goes down the drains.

d) Name four actions that householders can take to help minimise nutrient pollution of roadside drain water.

e) List four reasons why it is important to conserve our native biodiversity.

Short answer 2004 d & eAnother problem is caused by the fertilisers used in agriculture and gardens. In particular, phosphate

fertiliser can kill native plants that require little phosphate and it also causes toxic algal blooms in waterways. Part of the problem is caused by the fact that roadside drains in urban areas drain into waterways, carrying with them anything that goes down the drains.

d) Name four actions that householders can take to help minimise nutrient pollution of roadside drain water.

Use low-phosphate/slow release/organic fertilizerDon’t wash cars on drivewaysDon’t flush food scraps down drainsDispose of pet droppings correctlyMinimize fertilizer use/Plant natives that minimize fertilizer use/smaller gardensUse low-phosphate detergents and household productsDon’t overwater/use a wetting agentDon’t overfertilizeDon’t fertilize in winter

e) List four reasons why it is important to conserve our native biodiversity. Aesthetic value of biodiversityEthics – is it right to destroy biodiversity?Custodial – we should preserve biodiversity for future generationsUtility – biodiversity may provide useful products (e.g. medicines)Ecosystem stability – biodiversity contributes to ecosystem servicesRecreationEcotourismScientific researchEducationBetter ability to cope with environmental change/greater genetic diversity

Extended answer 2006 37d Conservation of biodiversity in our ecosystems is a very high priority for

biologists and governments around the world. However, not all organisms enjoy the same level of protection. Poison baits for rats and mice are sold in every supermarket but the community is horrified when whales are killed.

Use named examples to illustrate the biological factors that should be considered when deciding the level of protection that should be given to various species.

Extended answer 2006 37dConservation of biodiversity in our ecosystems is a very high priority for biologists and governments

around the world. However, not all organisms enjoy the same level of protection. Poison baits for rats and mice are sold in every supermarket but the community is horrified when whales are killed.

Use named examples to illustrate the biological factors that should be considered when deciding the level of protection that should be given to various species.

Up to 8 marks for individual points that have been explained/described• Aesthetics• Ethics/culture• Economics – cost of protection of species• Economics – benefit/importance to human economy of species (eg harvesting or tourism)• How common is the species?• How widespread is the species?• Is the species a pest or does it have known uses?• What is the chance that the species will go extinct?• If the species goes extinct, will it lead to the extinctions of other species/ecosystem instability?• What kind of protection is needed?• What is the recruitment rate/reproductive potential of the species?• What is our knowledge about the species?• Need to conserve genetic diversity/biodiversityUp to 2 additional marks for very well elaborated additional points, 1 mark for each pointExamples, can be rats/whales – up to 4 marksNamed example of species needing high protection• Reason for protecting species• Explanation of type of protection neededNamed example of species not needing high protection• Reason for not protecting species/giving low protection• Explanation of type of actions permitted against species

Genetic problem

• What is the pattern of inheritance?

• Write the genotypes for each individual

• Individuals II3 and II4 are expecting another child. What is the probability it will show this condition?

Genetic problem

• What is the pattern of inheritance? Autosomal dominant

• Write the genotypes for each individual

• Individuals II3 and II4 are expecting another child. What is the probability it will show this condition? 75%

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