Topic 4- Natural Selection And Genetic Modification

Question 1

What is evolution by natural selection?

Answer 1

Darwin came up with the theory of evolution by natural selection.
Evolution- the slow and continuous change of organisms from one generation to the next.
Natural selection- the process by which a characteristic gradually becomes more (or less) common in a population.
1. Species show wider genetic variation, selections pressures (E.g competition for resources).
2. Organisms better adapted to selection pressures more likely to survive and reproduce.
3. Alleles for characteristics that make organisms better adapted more likely to be passed on.
4. Beneficial characteristics gradually become more common in the population

Question 2

What is antibiotic-resistant bacteria?

Answer 2

Antibiotic resistance in bacteria supports Darwin’s Theory of evolution.
1.Random mutations mean some bacteria develop allele for antibiotic resistance.
2. Resistant bacteria survive the antibiotic and reproduce.
3. Resistance allele more common in population.
The emergence of other resistance organisms (E.g rats resistant to poison) also support Darwin’s theory.

Question 3

What are three fossils that provide evidence for human evolution?

Answer 3

1. Ardi (Ardipithecus ramidus)- 4.4 million years ago found in Ethiopia
2. Lucy (Australopithecus afarnsis)- 3.2 million years ago found in Ethiopia
3. Turkana Boy (Homo erectus) - 1.6 million years ago found in Kenya

Question 4

What stone tools did homo species use?

Answer 4

Simple pebble tools, tools from sculpted rocks and flint tools and pointed.

Question 5

What are three ways to date tools?

Answer 5

1. Structural features E.g simple tools are usually older.
2. Rock layers if they are deeper in the layer they are older.
3. Carbon-14 dating- used to date carbon- containing material found with tool.

Question 6

What is classification?

Answer 6

Classification- organising living organisms into groups bases on their features.
Originally, organisms were classified based in observable characteristics.
They are split into 5 kingdoms:
1. Animals
2. Plants
3. Fungi
4. Protists
5. Prokaryotes

Question 7

What domains are organisms split into?

Answer 7

1. Bacteria- true bacteria
2. Archaea- different type of prokaryotic cell first found in extreme places
3. Eukarya- including protists and animals.

Question 8

What is selective breeding?

Answer 8

Selective breeding- breeding plants or animals for particular characteristics.
1. Individuals with desired characteristics are bred together.
2. Repeated over generations.
3. Eventually all offspring have desired characteristics.
Benefits:
Agriculture and medical research
Risks:
Less genetic variation
Inbreeding can cause health problems

Question 9

What is the genetic engineering process?

Answer 9

Genetic engineering- transfer of a gene responsible for a desirable characteristic from one organisms genome into another organism.
It produces genetically modified organisms.
1. Restriction enzyme cuts out gene and cuts open vector DNA
2. Genes and vector are joined by ligase enzymes
3. Vector introduced to a new cell
4. New cell replicates, so many cells produce desired protein

Question 10

What are benefits and risks of genetic engineering?

Answer 10

Benefits:
Agriculture can make crops resistant to drought
Medicine treating infections
Risks:
Some GM animals have health problems
Affect food chains