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35 Cards in this Set
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Natural selection |
4 main points of darwins theory of evolution: * in any population, there are variations * in any generation, there are some individuals that do not reach maturity and produce - these individuals are removed from the population * individuals that survive and produce are well adapted to the environment (survival of the fittest) * favourable conditions passed on to offspring, becoming more and more common in the population |
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Evidence for crustal plates moving overtime |
- continents and oceans are carried on the large crustal plates of the earths surface, moving on top of the semi - molten interior - evidence: age of the sea floor around mid ocean ridges, matching edges of continents and fossils or similar organisms found in different parts of the world |
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Evidence that Australia was once part of a landmass called Gondwana |
Alfred wegner: one large land mass called Pangea - continental drift hypothesis * Gondwana and Laurasia Gondwana: Australia, Africa, Madagascar, NZ, South America Laurasia: Asia, North America, Europe - 60 million years ago, Australia split from Gondwana Geological evidence: - the rock strata around continental margins match exactly in many places, South Australia and Australia West Africa and east South America - spreading zones - new rock formed
Biological evidence: - fossil record and present day organisms provide evidence that Australia was part of Gondwana |
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Mid ocean ridges |
Sites where 2 crystal plates meet or move apart. The theory of continental drift suggests that as the continents drift apart magma wells up through the spreading floor and new crust is formed - radiometric dating - rocks towards edges of these mid ocean ridges are younger than those further in the margins - supporting the idea that rock near the edges of the spreading zones are newly laid down |
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Subduction zones |
Plates collide and fold, or one plate slides beneath the other, the formation of mountains and the continued movement of present day continents provides evidence to support the theory of plate tectonics Himalayan mountain range - India is sliding under the Asian plate |
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Fossil evidence |
The glossopterids are fossil plants found in rocks of the same age in Australia, Africa, India, South America, Antarctica and New Zealand Fossils of marsupials have been found on all the continents that were part of Gondwana - continents wrrr once joined |
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Extant organisms |
Southern beach recess areas found in forests of australia, New Guinea, New Zealand and South America - many plants and animals exist only where the nothifagus still live eg. Parasitic fungus, moss, bugs depending on the moss - many groups of animals in Australia have close relatives in South America, Africa, India and New Zealand but not in northern Asia, Europe or North America - animals include parrots - ratites - flightless birds (emus, ostrich) , marsupial mammals, geckos, earthworms, molluscs Proraeceae (Australian plants - Waratah and banksia) |
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Megafauna |
Animals similar to present day organisms but much bigger: large kangaroos, wombats, giant python - megafauna are not the ancestors of present animals - rather they both evolved from a common ancestor - over the last 50k years many species have evolved and become extinct |
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Why have most of the worlds megafauna become extinct? |
Climate change: suited to glacial conditions - died put snd animals more adapted to forest began to thrive. In Australia, temp changed from cold dry to warm dry and water sources began to dry up - many animals losing their habitat Human expansion: megafauna are large and slow which makes them susceptible to hunting. |
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The platypus |
Described with koala, kangaroo, wombat and emu - due to little technology. * primitive monotreme: lays eggs, absence of true teeth, no mammary glands but it has special glands able to secrete milk, has fur but also has a Horny beak - like a duck, webbed feet and a short tail * 1884 scientist were able to capture female eggs * highly tuned receptor able to pick up the weak electric fields of shrimp and worms - acute magnetic detectors |
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Monotremes? |
An egg laying mammal |
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Discuss examples of variations within a species |
* the small differences between organisms relating to the same species are called variations. These include feature such as eye colour, size, of biochemical differences Eg. The common Heath: this flower shows remarkable variations in the colour of the flowers, from pure white, to pink, to deep red |
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Variations? |
Variations occur due to genetic mutations or environmental adaptations |
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Variation within a species and the chances of survival of species when environmental change occurs |
heory of natural selection - there will always be variations within species - when environmental change occurs, the individuals that have a variation allow them to live in the new environment - survive will those without the variation eventually die out - the greater the variation within a species, the greater the chance that it will be able to survive in a situation of environmental change |
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Variation? |
Variation is caused by random segregation of chromosomes during meiosis - offspring is not identical to either parent because it involves the union of two gametes |
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Heredity |
The transfer of similar characteristics from parent to offspring |
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Theory of natural selection |
1. Variation 2. Natural selection - selective pressure 3. Survival of the fittest 4. Isolation - speciation - new species formed |
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Identify and describe evidence of changing environments in Australia over millions of years |
Evidence of glaciation: * glaciers leave a permanent mark on the landscape
Evidence of swamps: * coastal areas around east coast became swamps - sea levels began to rise - plant fossils
Evidence of warmer climate: * changing plant life after climates warmed |
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Areas within Australia that experience significant variations in temperature and water availability |
* temp variations inland deserts and grasslands can be very great. In the day the temp can be 40 degrees but fall very quickly at night. * temps can go from 20 degrees to below freezing in winter * most bodies of water are unreliable and fluctuate greatly |
Climate change * sclerophyll plants are adapted to dry conditions and poor soils - increased carbon in fossils shows an increase in fires - dry conditions - eucalyptus (regrow buds) |
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Changes in distribution of Australian species |
* as Australia became warmer and drier, rainforests shrank, grasslands and sclerophyll communities increased. Organisms well suited to these conditions undertook 'adaptive radiation' - sclerophykk family: eucalypts and acacias - both adapted to survive in dry hot conditions - placentals died out - except bats |
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Current theories that provide a model to account for these changes - climate |
Climate change (increasing aridity and frequency of fires) |
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Human impact |
Megafauna were hunted and killed Species evolved to become smaller - dingos were oredators Increased fires - farming techniques |
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Darwins observations of Australia flora and fauna, related to theory of evolution |
* when Darwin travelled around the world in the ship, the beagle, the similarities between organisms that he observed convinced him that an evolutionary tree existed * many Australia flora and fauna had similar counterparts from other parts of the world - organisms could evolve to become similar (convergent evolution) |
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Mitosis |
* cell division where 2 daughter cells are produced that are identical to the parent cell * is used for growth and repair * cells produced are diploid (same number of chromosomes to parent cell) * interphase, prophase, anaphase, metaphase, telophase |
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Meiosis |
* cell division that produces 4 cells with half the number of chromosomes compared to parent cell (haploid) * sex cells also called gametes * fuse together to form a zygote * 23 chromosomes in each haploid cell * similar chromosomes paired up - homologous |
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Variation during meiosis |
Crossing over - genetic variation (homologous chromosomes) Fertilisation - many combinations of chromosomes possible in gametes - resulting in a variety of gametes forming - haploid gametes |
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External fertilisation |
* process of gametes fusing to form diploid zygote - takes place outside body - aquatic animals - male and female gametes shot into the water in the hopes of fertilisation - millions are released to increase successfulness - cyclical reproductive behaviours - synchronised timing of gamete production and release - developments of courtship and mating behaviours |
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Internal fertilisation |
* inside body * male gamete transferred directly to female gamete * number of female gametes is reduced greatly * protected and safe within female body * copulation |
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Relative success of fertilisation forms |
* external fertilisation is successful in water as the gametes can spread very far and wide in the water increasing the chances of meeting other gametes encouraging fertilisation - zygotes are able to spread to large areas - internal fertilisation enabled the colonisation of land as the watery environment needed is provided by the females physiology - driest environments could be colonised |
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Pollination |
* transfer of pollen from an anther to a stigma in flowering plants (angiosperms) and from male to female cones in conifers (gymnosperms) - self pollination - daisy - pollen matures and anther splits open releasing pollen on stigma - cross pollination - grasses - pollen from a flowers anther pollinates a flowers stigma from a different plant: cross - pollination (Wind) |
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Insect pollination |
Insect and plant dependant on each other: plant needs a pollinator and insect needs food - bees go to the stigma and deposit pollen from the last flower they visited - bottle brush or eucalypts |
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Bird pollination |
Birds pollinate red flowers - Waratah - nectar feeding honey eaters |
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Mammal pollinatikn |
Mammals - bats and possums move over flowers |
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Seed dispersal |
* the spreading of seeds away from the parent plant - species are more likely to survive fire, disease, environmental change |
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Asexual reproduction advantageous? |
* small mating population * if the environment is unchanging, and the characterises are well suited to the environment, asexual reproduction would be advantageous * relatively quick |
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