Biology 12

Introduction of new species Examples of introduced species

Reasons for introduction Effects of introduction

Fox For hunting Predation of native species

Cat, dog Escaped from houses, dumped Predation of native species

Rabbits Brought in as food source Competition for feed, overgrazing & burrows cause erosion

Goats, sheep, cattle, horses, camels, water buffalo

Escaped from farms, dumped Competition for feed, overgrazing causes erosion, hooves damage river banks

Carp Escaped, dumped Competition for food sources, predation, reduces native species

Cane toad Brought in to control cane beetle

Predation of native species

Corellas, cockatoos Escaped, dumped Compete for resources – especially nesting sites

Prickly pear, brambles, arum lilies

Escaped, dumped Competition, reduces native species

Duckweed, water hyacinth

Escaped, dumped Chokes water ways

Removal of organisms Examples of removed organisms

Reasons for removal Effects of removal

Wolf, puma Removal of predators so there would be more deer to hunt

Overpopulation of deer, ate out the food supply, ecosystem destruction

Tasmanian tiger Hunted to extinction (thought to be danger to livestock)

Extinct native species

Trees Clearing for mining, farming, housing

Salinity, erosion, loss of habitat for native species

Hollow logs & dead wood

Firewood, aesthetics, clearing for mining, farming, housing

No nesting sites for native birds, especially cockatoos

Wetland organisms Filling in for housing or landfill Salinity, erosion, loss of habitat, downstream pollution

Elephant, rhino, orang utan, etc

Poaching for tusks, horns, fur, pet trade

Disrupts ecosystems, threat of extinction for some hunted species

Pollution

Examples of pollution Causes of pollution Effects of pollution

Carbon dioxide Combustion –eg cars, factories, etc

Greenhouse gas global warming

Carbon monoxide Combustion –eg cars, factories, etc

Poison

Nitrogen dioxide, sulfur dioxide

Factories, mining Combines with water in the air to produce nitric & sulfuric acid acid rain

Methane Ruminants (eg sheep & cattle), rotting garbage (land fill)

Green house gas global warming

Fertilizers Farming, gardens Algal bloom (eutrophication)

Pesticides Farming, urban spraying Ecological magnification

Heavy metals eg mercury, lead, cadmium

Factories, mining Poisons

Sewage Human waste Algal blooms, disease

Greenhouse effect - global warming• Main causes

Build up of greenhouse gases in the atmosphere – carbon dioxide (combustion), methane (ruminants & rotting garbage) & CFC’s (refrigerators & air conditioners)

• Main effects

Increased global temperatures Rise in sea levels (thermal

expansion & polar icecap melting)

Melting of glaciers

Changes in weather patterns – some places (eg Australia get dryer, others getter wetter)

• Possible solutions

Reduce emissions

Plant more trees, use less fossil fuels, reduce ruminants

Normal –Some greenhouse gases present

Global warming–Increased greenhouse gases present

Radiation from sun reaches EarthSome absorbedSome reflected and leavesSome reflected, but bounces back and warms Earth

Radiation from sun reaches EarthSome absorbedLess reflected and leavesMore reflected, and bounces back and warms Earth

Greenhouse effect - global warming 2

Global currents & climate

Global currents drive many of our weather patterns and also determine productivity of many marine ecosystems

A change in salinity at the ventilation areas could lead to a reduction in the current changes in climate.A decrease in surface temperature means less CO2 is trapped

Climate change – is it happening?

Athabasca glacier

Previous ice level

Food resources scarcer so bears are looking after cubs for 2 years, instead of 1 breed every 3rd year instead of every 2nd year

Average rainfall decreasing

Healthy pines

More pines are affected by pine beetle – winters not cold enough to kill off adult beetles

Lake Louise – May 26th 2008 (last month of spring) – still frozen

Pines affected by pine beetle

Deterioration of the ozone layer• Main causes

CFC’s, halons & methyl bromine (& jet planes) destroy ozone in atmosphere

• Main effects

Ozone (O3) absorbs UV radiation.

If ozone is reduced more radiation gets through

This leads to increased temperature

Higher radiation increase risk of skin cancers & eye problems in people, higher risk of mutation & damage in unicellular organisms

Damage to algae may cause loss of biomass/ ecosystem collapse in marine ecosystems

• Possible solutions

Reduce use of CFC’s

Care with disposal of gases (eg old refrigerators, servicing air conditioners

Normal Ozone prevents most of UV radiation from entering

Ozone depletionLess ozone means more UV radiation can enter

Ozone depletion

Ozone depletion over south poleDobson units measure amount of ozone present

Desertification

• Main causes clearing for houses, farms, mining etc

• Main effects loss of soil fertility, loss of habitat, soil erosion, salinity, damage to waterways – fertilizers & pesticides

• Possible solutions clear less, plant more trees, use less water, fertilizers & pesticides

Effects of increased human population

Settlement patterns

More people living in cities, cities become larger

Resource use:

Energy

Water

Food

Increases – leading to scarcity in fuel, water & food supply more land cleared for farming, increased use of pesticides & fertilizers

The environment:

Desertification

Eutrophication

Pollution

More land is cleared for farming desertification

More fertilizers are used eutrophication

More people more pollution (sewage, combustion, industrial pollution)

Short answer TEE 2002 33a, b, cOne of the biggest threats to urban and agricultural

bushland areas is invasion by introduced plants, particularly grasses. This can be seen in comparable transect sketches made at different locations in a jarrah forest in South Western Australia.

a) Name four ways that humans may have introduced non-native plants to bushland areas.

b) One of the most obvious ways that introduced grasses would affect native species is by competition. Name four things that the grasses and native plants would compete for.

c) The transect diagrams show three layers in the forest, the canopy, the understorey and the ground storey. Predict which layer would be most severely affected by competition from introduced grasses and give two reasons why.

Short answer TEE 2002 33a, b, cOne of the biggest threats to urban and agricultural bushland

areas is invasion by introduced plants, particularly grasses. This can be seen in comparable transect sketches made at different locations in a jarrah forest in South Western Australia.

a) Name four ways that humans may have introduced non-native plants to bushland areas.

Seed escape from agriculture or horticulture, bushwalking, pets, vehicles, animals, animal droppings, dumping, revegetation, restoration, discarded food, camping waste, deliberate planting, waterways transport.

1 mark each, maximum 4

b) One of the most obvious ways that introduced grasses would affect native species is by competition. Name four things that the grasses and native plants would compete for.

Water, mineral nutrients (but only 1 nutrient counts), light (suppressing seedlings), root anchorage, soil oxygen, pollination opportunities, dispersal agents for seed.

1 mark each, maximum 4

c) The transect diagrams show three layers in the forest, the canopy, the understorey and the ground storey. Predict which layer would be most severely affected by competition from introduced grasses and give two reasons why. Any storey will be accepted as prediction, but reasons and explanations must relate to prediction. e.g., ground storey, more likely to be smothered, compete for water e.g., canopy, seedlings are smothered and out competed for water by grass1 mark for each reason 1 mark for each explanation

Short answer TEE 2002 33d, ed) Fire is a regular event in natural bushland. Significant grass cover in these areas

can change the intensity of the fire and cause great long-term damage to the ecosystem.

i) Describe one way in which fire can be beneficial to natural Australian bushland ecosystems.

ii) Describe one way in which a fire in a heavily grass infested area might be

harmful to the ecosystem.

e) For some introduced species biological control has been used. Name one example of biological control used in Australia and state three important conditions that must be met in any biological control programme.

Short answer TEE 2002 33d, e

d) Fire is a regular event in natural bushland. Significant grass cover in these areas can change the intensity of the fire and cause great long-term damage to the ecosystem.

i) Describe one way in which fire can be beneficial to natural Australian bushland ecosystems.

Benefit from seed germination, ash bed provision, regenerate from lignotuber, epicormic growth. Animals may be used as well as plants, with points including: promotes vegetation mosaic, promotes tree hollows, kills parasites in roosts. Destroys non-native species not fire adapted. 1 described benefit 2 marks

i) Describe one way in which a fire in a heavily grass infested area might be harmful to the ecosystem.

Intense fire may kill plants, which are resistant to mild fire or give fast colonising grasses a chance to take over. Grasses may increase fuel loads, causing hotter, more destructive fires. Animal examples are destruction of habitat, animals killed directly. Fire reduces food/biomass/productivity for grazers. 1 described problem 2 mark

ii) e) For some introduced species biological control has been used. Name one example of biological control used in Australia and state three important conditions that must be met in any biological control programme.

Must name the pest and the biological control. E.g., Dung beetle and bush fly, Cactoblastis and prickly pear, cane beetle and cane toad, myxomatosis/calici virus and rabbits, sterile male fruit fly. 1 mark for example

Controls must have host specificity, breed/survive well in Australian conditions, not become pests themselves, not be toxic to native species and not introduce any pathogen.

1 mark for each quality, maximum 3

Extended answerGive examples to illustrate how the action of selective forces can lead

to extinction.

Give examples to illustrate how humans can contribute to extinction.

Extended answerGive examples to illustrate how the action of selective forces can lead to

extinction.Selection involves: Variation due to differences in allele combinations Overpopulation struggle for existenceSelection pressures survival of the fittest inheritance of successful

alleles/variations gene frequency changesIf the selection pressures are too severe, or changes occur too fast, or a variation

doesn’t exist that is capable of coping with the selection pressure, not enough organisms will survive to continue the species.

Examples include – Disasters that destroy habitats eg volcanoes, meteor strikes eg dinosaur

extinctionEnvironmental changes – eg global warming, ice ages, sea level changes – that

may affect habitat eg mammoths disappeared after the planet warmed up & their habitat disappeared

Extended answerGive examples to illustrate how humans can contribute to extinction.Humans can contribute to extinction by:Habitat destruction eg clearing, removal of hollow logs nowhere for the

organisms to live or breed eg panda, orang utan, elephantsPredation/hunting – removal of organisms eg dodo, Tasmanian tigerIntroduced species – compete or predate eg rabbits, foxes Spread of diseases eg Jarrah diebackDisruption of natural cycles eg fires – may disrupt ecosystemsEnvironmental changes• Changes in flows of rivers – dams, irrigation may interrupt breeding/migration

eg salmon• Draining of swamps – loss of breeding sites & migration stops eg frogs,

tortoise• Water pollution eg fertilizers, pesticides, heavy metals – may kill species,

cause algal blooms eg native fish• Air pollution eg acid rain, greenhouse, ozone depletion - kills organisms eg

frogs or destroys habitatHuman changes are usually more rapid than natural changes, so species don’t

have time to adapt.

Extended answer 2002 37a Over the next few decades several missions by spacecraft will look for evidence of life elsewhere in the

solar system. Two places that will be explored by spacecraft landers are the planet Mars and Europa, a satellite of the planet Jupiter.

Mars is known to have a thin atmosphere of carbon dioxide and nitrogen. Although water vapour is present in the atmosphere and water ice is present in polar regions, there are no oceans, rivers or lakes. Temperatures on Mars vary from -128°C at the poles in winter to 37°C at the equator in summer. Scientists believe liquid water may be found somewhere beneath the surface of the planet.

Europa is much further from the sun. It has no atmosphere and its surface is covered mostly by ice several kilometres thick. There is good evidence that oceans of liquid water lie beneath the ice. The average surface temperature of Europa is - 180°C but it is thought that the oceans underneath are warmed by tidal forces and may have temperatures similar to those on Earth.

What particular difficulties would be faced by Earth-like organisms living on (i) Mars, and (ii) Europa?

In terms of the requirements of living organisms, explain why the conditions on Mars and Europa may be too hostile for life forms as we know them on Earth.

Extended answer 2002 37aOver the next few decades several missions by spacecraft will look for evidence of life elsewhere in the

solar system. Two places that will be explored by spacecraft landers are the planet Mars and Europa, a satellite of the planet Jupiter.

Mars is known to have a thin atmosphere of carbon dioxide and nitrogen. Although water vapour is present in the atmosphere and water ice is present in polar regions, there are no oceans, rivers or lakes. Temperatures on Mars vary from -128°C at the poles in winter to 37°C at the equator in summer. Scientists believe liquid water may be found somewhere beneath the surface of the planet.

Europa is much further from the sun. It has no atmosphere and its surface is covered mostly by ice several kilometres thick. There is good evidence that oceans of liquid water lie beneath the ice. The average surface temperature of Europa is - 180°C but it is thought that the oceans underneath are warmed by tidal forces and may have temperatures similar to those on Earth.

What particular difficulties would be faced by Earth-like organisms living on (i) Mars, and (ii) Europa?

In terms of the requirements of living organisms, explain why the conditions on Mars and Europa may be too hostile for life forms as we know them on Earth.

Particular difficulties (max 4 marks):

• Low temperatures • Lack of oxygen

• CO2 absent on Europa • CO2 levels too high / too low on Mars

• Lack of water on Mars • Low light intensities

• High UV incidence

Explanations for conditions being too hostile (2 marks per good explanation):

• Effects of low temperature / heat levels • Effects of lack of water

• Effects of low oxygen • Effects of low / high CO2

• Effects of low light intensity • Effects of UV light