Genetics and evolution

Question 1

Who is known as the father of evolution

Answer 1

Charles Darwin a scientist who lived in the 19th century

Question 2

What was the term coined by Charles Darwin for his theory of evolution?

Answer 2

Natural selection

Question 3

Explain the principles behind Darwin’s theory of evolution.

Answer 3

Evolution explains how different species can develop from one common ancestor over a period of millions of years.
Natural selection means that some individuals in a population who compete for resources are better adapted to the environment and are therefore more successful.
The individuals which are most highly adapted survive and reproduce, therefore their character traits are passed on the further generations.
Changes in an environment can mean that some individuals or some species which are less well adapted die out
Species which cannot compete can become extinct.
Adaptations lead to biodiversity.

Question 4

Define the term species

Answer 4

A species is a group which can breed with each other to provide fertile young.

Question 5

Explain the difference between the theories of creationism and evolution

Answer 5

Creationism is a religious belief that the earth was created by God over 7 days.

Evolution is the theory that life developed over billions of years with organisms adapting traits or characteristics in order to survive in their differing environments. The most well adapted survived to reproduce and new species were developed by natural selection over a long period of time.

Question 6

Identify forms of evidence which substantiate Darwins theory of evolution

Answer 6

1. Fossils - the remains of organisms found preserved in rocks
2. Genetic mapping of genomes
3. Antibiotic resistance in bacteria

Question 7

Explain the different ways in which fossils are formed

Answer 7

1. Fossils such as Tollund man are formed when the conditions prevent the decay of organsims. In this case the human body was preserved in a peat bog where there is no oxygen and a low pH. The acidic anaerobic conditions prevented microorganisms form breaking down the body.
2. When organisms are covered by layers of sand and silt on river or sea bed. The layers form over the organism pushing down or compressing it. The water is squeezed out leaving minerals which turn to stone as the organism decays.
3. An organism can leave tracks, eggs or burrows which become preserved in a similar way, dinosaur footprints and eggs have been found as fossils

Question 8

Explain how the fossil record proves the theory of evolution

Answer 8

Fossils can be dated by looking at the age of the rock in which they are found. The fossil record shows changes which have occurred in species over time.
A good example is the way that horses hooves have changed over the years. Horses had large hooves to stop them sinking into the marshes. As the marshes dried up horses hooves became smaller. Horses with smaller hooves could run away from predators more quickly and so had an advantage. Natural selection meant that the horses with the smaller hooves had adapted better to the conditions and so reproduced more. The fossil record shows the adaptation to smaller hooves.
There are gaps in the fossil record as not all species became fossils, especially those whose bodies were made from soft tissue.

Question 9

Explain how the development of antibiotic resistant bacteria provides evidence for evolution
Give an example.

Answer 9

1. A mutation occurs which makes the bacteria resistant to antibiotics.
2. The bacteria carrying the mutation survives antibiotic treatment and reproduces passing on its genetic advantage to the next generation
3. Eventually all of the bacteria are resistant to antibiotics and treatment no longer works.
4. The bacteria have evolved to become antibiotic resistant.

An example of this is MRSA which has evolved to become resistant to antibiotics. It is dangerous for hospital patients who have had surgery and so measures are in place to test patients for the bacteria before surgery, strict hygiene and isolation of vulnerable patients.

Question 10

Describe how overuse and misuse of antibiotics has lead to antiobiotic resistance in bacteria

Answer 10

1. Doctors used to prescribe antibiotics much more readily, this has been tightened up, the more antibiotics are used the more chance of resistant strains developing.
2. Animal feed contained antibiotics so the animals were given them even if they were not ill, this was to to promote growth and it was thought prevented disease. This has been banned in many countries including the UK.

Question 11

Explain why antibiotic resistance is a concern for doctors

Answer 11

1. Antibiotic resistant strains of bacteria are developing quickly
2. Producing new antibiotics is expensive and takes many years.
3. If bacteria become resistant to antibiotics many diseases which currently can be cured will not be able to be.

Question 12

Explain the term extinction

Answer 12

A species is extinct when there are no more of them left living.

Question 13

Explain the term mass extinction

Answer 13

A large number of extinctions happening at the same time usually caused by a catastrophe.

Eg an asteroid hit Mexico about 66 million years ago which forced a superheated cloud of dust and ash into the sky triggering global volcanic eruptions and earthquakes. Sunlight was blocked, cooling the earth and preventing photosynthesis. Many species including the dinosaurs became extinct due to lack of food.

Question 14

Identify causes of extinction

Answer 14

1. Natural disasters
2. Climate change
3. New diseases.
   4 Human activity such as deforestation, introduction of new preditative species, pollution, hunting etc

Question 15

What is a predator

Answer 15

An animal which hunts and kills other animals