Topic 4

Explain Darwin's theory of evolution by natural selection

Natural selection: variations of some individuals make them better at coping with the change than others and are more likely to survive-survival of fittest.

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2) Explain Darwin's theory of evolution by natural selection

inheritance:the survivors breed-pass on their variations to their offspring.Next generation contains more individuals have better adapted variations

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3) Explain Darwin's theory of evolution by natural selection

Evolution:if environmental conditions remained changed-natural selection occurs again-new species evolves with all individuals having better adapted variations.

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Emergence of resistant organisms supports Darwin's theory of evolution including antibiotic resistance in bacteria.

In a population of bacteria,some bacteria more resistant than others & take longer to be killed.People who take antibiotics to treat infection often stop taking it early as they fell better.

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2)Emergence of resistant organisms supports Darwin's theory of evolution including antibiotic resistance in bacteria.

It leaves resistant bacteria alive and reproduces and spread causing infections that cannot be treated with the antibiotic because bacteria are now resistant.

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Human evolution based on fossils for Ardi

4.4 million year old fossilised bones from female-extinct-human like species. 1.2 m tall and 50kg .leg bones suggest she may have been able to walk upright.long arms big toes that stuck out allowed her to climb trees.

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Human evolution based on fossils for Lucy

lived 3.2 million years ago. 1.07m tall . probably walk upright.toes were curved compared to humans today

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Leakey discovery of fossils 1.6 million years ago

Almost complete skeleton was found by Leakey in Kenya providing evidence humans were evolved in Africa.This species was tall-1.79m- and strongly built.

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Human evolution based on stone tools: a) development of stone tools over time.

Oldest tools are very simple - helped skin an animal or cut meat Tools found in more recent rock are much more sophisticated.

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Human evolution based on stone tools: b) dated from their environment.

earliest evidence-3.3 million years ago. Work out the different ages of different layers of rock. Assume stone tool is about the same age as that layer of rock.

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Describe how genetic analysis led to suggestions of 3 kingdoms rather than 5.

Archaea were found to have unused sections. This led to propose that all organisms should be divided into 3 domains.

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What is Selective Breeding?

When humans choose an organism that has a certain characteristic and breed more of these organism making sure the characteristic is more obvious.

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Selective Breeding's impact on food plants and on domesticated animals.

They are both often selectively bred for: 1) disease resistance(how well they cope with disease) 2) Yield(how much useful product they make) 3) Coping with certain environmental conditions. 4) Fast growth 5) Flavour

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What is Genetic Engineering?

A process which involves modifying the genome of an organism to introduce desirable features.

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1)Describe main stages of Gentic Engineering

Scientists use restriction enzymes to cut a useful gene out of an organisms DNA.This cutting leaves strands of DNA with jagged ends called sticky ends. If two sticky ends match they can be joined together by the enzyme called ligase.

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2)Describe main stages of Gentic Engineering

Any DNA molecule used to carry new DNA into another cell is called a vector.

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Benefits and risks of Genetic Engineering

being able to produce organisms with desired features quickly. On the other hand, it has some potential risks, for example, the inserted genes may have unexpected harmful effects.

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Ethical implications

some people are concerned about the health risk of genetically modified food. Others think it is wrong to create new life forms, or to move genes between different species, especially if this causes harm.

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What is selective breeding?

process by which humans use animal breeding and plant breeding to selectively develop particular phenotypic traits (characteristics) by choosing which typically animal or plant males and females will sexually reproduce and have offspring together.

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Steps in selective breeding?

1) Decide which characteristics are important. 2) Choose parents that show these characteristics. 3) Select the best offspring from parents to breed the next generation. 4) Repeat the process continuously

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Benefits and Risks of selective breeding-Risks

Future generations of selectively bred organisms will all share very similar genes. This could make some diseases more dangerous as all the organisms would be affected. Also there's increased risk of genetic disease caused by recessive genes.

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Benefits and Risks of selective breeding-Benefits

Selective breeding can produce fitter and stronger animals that are of a higher yield of milk, meat or eggs for example some cows are been breed to produce more meat .

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2) Benefits and Risks of selective breeding-Benefits

This can be good as we can produce animals better suited to survive in poor climates or marginal conditions and this can preserve human food supplies and can save life.

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