| Evolution of time - 17 Stages | 1) Archean Eon - About 3.5 B Years Ago - 1st Bacteria (Prokaryotes)
2) Proterozoic Eon - About 2 B Years ago - 1st Organelles (eukaryotes)
3) Proterozoic Eon - About 1 B Years ago - 1st Multicellular Organisms (algae, jellyfish, worms)
4) Palaeozoic Era - About 500 M Years ago - 1st fish
5) Palaeozoic Era - About 450 M Years ago - 1st land plants & Fungi
6) Palaeozoic Era - About 390 M Years ago - 1st Amphibians, insects & reptiles. Much of the land covered in fern forests (which later become coal)
7) Palaeozoic Era - About 250 M Years ago - 1st First mass extinction
8) Mesozoic Era - About 200 M Years ago - 1st mammals & Birds
9) Mesozoic Era - About 130 M Years ago - 1st flowering plants
10) Mesozoic Era - About 115 M Years ago - 1st dinosaurs
11) Cenozoic Era - About 65 M Years ago - 2nd Mass extinction, Dinosaurs die out
12) Cenozoic Era - About 55 M Years ago - 1st Modern mammals & birds
13) Cenozoic Era - About 35 M Years ago - 1st Grasses
14) Cenozoic Era - About 3 M Years ago - 1st Hominids
15) Cenozoic Era - About 200 K Years ago - Neanderthals & 1st Homo sapiens
16) Cenozoic Era - About 100 K Years ago - Humans colonise habitable land masses, 30 K Years ago - Neanderthals die out, leaving homo sapiens as only species of humans 17) Cenozoic Era - About 20 K Years ago - Agriculture begins |
| Jean-Baptiste Lamarck's theory | 19th Century, before Charles Darwin
1) A characteristic which is used more and more by an organism becomes bigger and stronger, and one that is not used eventually disappears
2) any feature of an organism that is improved through use, is passed to its offspring
EXAMPLE: Giraffes, he believed, had short necks, but by constantly stretching them, they elongated
HOWEVER: It is now commonly accepted that Lamarck's ideas were wrong. For example, simple organisms are still detected in all varieties of life, plus it is now known that mutations can create variation such as neck length |
| Darwin's Theory of Natural Selection | SUMMARY:
1) 5 year voyage, 19th Century, Studied variation of: plants, animals & fossils, on 4 continents on the HMS Beagle
2) observed many organisms including finches, tortoises and mocking bird (during his 5 week visit to the Galapagos Islands).
3) Published his scientific work 28 yrs after his voyage in the book On the Origin of Species, which was published in 1859. His observations were backed by many years of experimentation
PROPOSED THAT:
1) individual organisms within a particular species show a wide range of variation for a characteristic
2) individuals with characteristics most suited to the environment are more likely to survive to breed successfully
3) the characteristics that have enabled these individuals to survive are then passed on to the next generation
4) Eg, finches: diff beak/claw sizes depending on the local food source, because the islands were far from the mainland, the finches that had arrived changed over time
ISSSUES:
1) the theory challenged the idea that God made all animals and plants that live on Earth (creationism)
2) there was insufficient evidence when the theory was published to convince many scientists
3) the mechanism of inheritance and variation was not known until 50 years after the theory was published |
| What did Alfred Russel Wallace do? | 1) admirer of Darwin and a fellow naturalist
2) published scientific ideas jointly with Darwin in 1858
3) proposed a theory of evolution, which matched Darwin's unpublished ideas this encouraged Darwin to collect his scientific ideas and collaborate with Wallace
4) best known for studying warning colouration in animals (Eg, Golden Birdwing Butterfly & his theory of specification) |
| What are fossil fuels? | Fossil - The preserved remains of a dead organism from millions of years ago, found in rocks &can be formed from:
1) hard body parts, such as bones and shells, which do not decay easily or are replaced by minerals as they decay
2) preserved traces of organisms, such as footprints, burrows and rootlet traces, become covered by layers of sediment, which eventually become rock |
| How are animals preserved if conditions aren't correct for decay? | If conditions aren't correct for decay: dead animals and plants can be preserved in amber, peat bogs, tar pits, or in ice
AMBER: a substance that is formed from hardened tree sap or resin, allows the whole organism to be seen clearly
PEAT BOG: Eg, Lindow man. Acidic, oxygen-free conditions in the peat bog meant that the man's skin, hair and many of his internal organs were extremely well preserved (unusual process). Another eg of a body preserved in ice - Oetzi. Mummified ancient man found in 1991, near Australian-Italian border. 5,00 years old, extensively examined, his gut, bacteria, pollen contained in some clothes |
| How do Bacteria become Resistant? | ANTIBIOTIC RESISTANCE:
- Bacteria can evolve quickly because they reproduce at a fast rate. Mutations of bacteria produce new strains
- Some bacteria might become resistant to certain antibiotics, such as penicillin, (can't be destroyed by the antibiotic), bacteria evolution is an example of natural selection
Development of resistance:
1) random mutations occur in the genes of individual bacterial cells
2) some mutations protect the bacterial cell from the effects of the antibiotic
3) bacteria without the mutation die or cannot reproduce when the antibiotic is present
4) resistant bacteria can reproduce with less competition from normal bacterial strains |
| What is MRSA? | MRSA:
No. of resistant strains has increased, partly due to the misuse of antibiotics, resulting in more infections that are hard to control. Eg, MRSA is v/dangerous as its become resistant to most antibiotics. |
| What causes Extinction? | - animals aren't adapted to their environment
FACTORS CAUSING EXTINCTION:
- new diseases
- new predators
- new, more successful competitors
- changes to the environment over geological time, such as climate change
- a single catastrophic event, such as a massive volcanic eruption or a collision between an asteroid and the Earth
- specification
Fossils show evidence of extinction |
| What are Dodo's & how did they become extinct? | DODOS:
- Heavily-built, flightless bird (swan size)
- Lived on Mauritius (an island in the Indian ocean). Which was uninhabited & the birds had no natural predators
- Mauritius was colonised by the Dutch in 1638, dodos were hunted for food (easy to catch and new competitors were brought onto the island like pigs, cats, rats), they ate dodos' eggs & young
- Dodos became extinct within 80 years |
| What is Pencilin? | PENCILLIN:
- first antibiotic to be produced on a mass scale(1940's), its derived from Penicillium fungi. Many more discovered in 1950s and 1960s
- new discoveries have slowed down recently as many scientists felt it was unnecessary, also they're costly and very slow to develop
- Some scientists fear that we are fighting a losing battle as it may ultimately lead to people dying from simple infections (eg, following operations) |
| How do you reduce resistant strains of bacteria? | REDUCE RATE OF RESISTANT STRAINS BY:
- Doctors shouldn't prescribe antibiotics inappropriately (for the treatment of non-serious infections)
- Patients should always complete the full course of antibiotics to ensure all bacteria are killed and none survive to mutate and form resistant strains
- Agricultural use of antibiotics should be restricted |
| How do Fossil fuels show evidence of evolution & What are the flaws of using Fossil fuels as evidence for evolution | HOW IT WORKS - Fossils of the simplest organisms are found in the oldest rocks, and fossils of more complex organisms in the newest rocks (supports Darwin's theory of evolution that life forms eventually formed into complex ones)
FLAWS - There are gaps in the fossil record because many early forms of life were soft-bodied, which means that they have left few traces behind or traces destroyed due to geological activity |
| What are Causes of the Rising of New Species? | NEW SPECIES ARISING DUE TO:
1) genetic variation - each population has a wide range of alleles that can control their characteristics
2) natural selection - the alleles which help an organism to survive are selected in each population
3) speciation - the populations become extremely varied and successful interbreeding cannot happen anymore |
| How does Isolation Influence the rising of New Species? | NEW SPECIES ARISING DUE TO ISOLATION:
1) two populations of a species can become geographically separated because of the environment
2) isolation can prevent interbreeding and the combination of genes within a species
3) different mutations can take place in the isolated groups and create different phenotypes within a particular location
4) over time species may evolve to be different to each other, and they will not be able to interbreed |
| How does survival of the fittest work? | 1) Individuals in a species show a wide range of variation due to different genes
2) Individuals with characteristics most suited to their environment are more likely to survive and reproduce (survival of the fittest). Allowing them to be to be successful within their environment are passed on to their offspring, which results in these specific genes becoming more common(vice versa) |
| How can variation lead to 2 different species that can no longer interbreed? | 1) Over a period of time, a species will gradually evolve
2) Both genes and the environment can cause variation, but only genetic variation can be passed on to the next generation
3) If two populations of one species become increasingly different in phenotype that they can no longer interbreed to form fertile offspring, this can result in the formation of two species
EXAMPLE: Peacocks - females are more likely to mate males with more colourful tails, overtime peacocks have become more colourful, Bacteria - becoming resistant to antibiotics |
