Topic 4 - Natural Selection And Genetic Modification

Question 1

What is evolution?

Answer 1

The slow continuous change of organisms from one generation to the next.

Question 2

Darwin’s theory stage one (V)

Answer 2

Individuals in a population show genetic variation due to alleles or mutations

Question 3

Darwin’s theory stage 2 (O)

Answer 3

Organisms produce more offspring than survive

Question 4

Darwin’s theory stage 3 (S)

Answer 4

Survival / selection pressures. Limited resources cause competition between individuals eg food, finding a mate, water

Question 5

Darwin’s theory stage 4 (A)

Answer 5

Adaptations, species better adapted to the environment are more likely to survive

Question 6

Darwin’s theory stage 5 (R)

Answer 6

Reproduce, individuals that survive pass on their advantageous genes

Question 7

Explain how antibiotic resistance occurs in bacteria

Answer 7

Bacteria could develop mutation that makes them less affected by antibiotic. Ability to resist antibiotic is a big advantage. The resistant bacterium survives longer than non resistant so it reproduces. Leads to allele for antibiotic resistance to be passed on.

Question 8

Describe how ardi shows evolution from 4.4 million years ago

Answer 8

Structure of feet suggests she climbed trees. Ape like toes. Long arms and short legs like an ape. Brain size the same as chimpanzees. Structure of legs = walked upright. Structure of arms = walked on hands too

Question 9

Describe how Lucy shows evolution from 3.2 million years ago

Answer 9

Arched feet, more adapted to walking. Arms and legs size were between apes and humans. Brain was slightly larger than ardi. Walked upright and more efficiently

Question 10

Describe how leakey’s discovery of fossils from 1.6 million years ago show human evolution?

Answer 10

Fossil skeleton of homo erectus was a mixture of ape like but more human like than Lucy. Short arms and long legs were human like. Larger brain size. Walked upright

Question 11

How have tools developed over time to show human evolution?

Answer 11

Stone tools went from being blunt + pebble like to being sharp + arrowhead shaped. Means brains must’ve got larger

Question 12

How can stone tools be dated?

Answer 12

Looking at structural features, rock layers, carbon 14 dating can date material

Question 13

What are the 5 kingdoms?

Answer 13

Animals, plants, fungi, prokaryotes (single celled, no nucleus), protists (eukaryotic eg algae)

Question 14

How has genetic analysis lead to 3 domains rather than 5 kingdoms?

Answer 14

Technology improved, understanding of genetics increased. Using genetic analysis we found members of prokaryotic kingdom weren’t as closely related so he split it into 3 domains.

Question 15

What are the three domains?

Answer 15

Archaea - look like bacteria, found in hot springs + salt lakes
Bacteria - contains true bacteria eg E. coli
Eukarya - broad range of organisms: fungi, plants, animals, protists.

Question 16

What is selective breeding?

Answer 16

When humans artificially select plants or animals that will breed so genes for particular characteristics remain.

Question 17

What is the process for selective breeding?

Answer 17

Select livestock with characteristics you want.
Breed
Select best offspring + breed them
Continue over several generations + desirable trait gets stronger

Question 18

Explain why selective breeding is important in agriculture

Answer 18

Genetic variation means some have better characteristics for producing meat. Improve meat yields farmer selects cows + bulls and breed them etc

Question 19

How does selective breeding affect the gene pool?

Answer 19

Reduces number of different alleles in a population

Question 20

How does inbreeding cause health problems?

Answer 20

More chance of organisms inheriting harmful genetic defects when gene pool is limited.

Question 21

How are animals affected by selective breeding?

Answer 21

Some dogs are susceptible to certain defects due to inbreeding eg pugs have breathing problems.

Question 22

What happens if a new disease appears in selective breeding?

Answer 22

Not much variation so less chance of resistance alleles being present

Question 23

What is genetic engineering?

Answer 23

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

Question 24

What is a vector?

Answer 24

Something used to transfer DNA into a cell. Two types: plasmids + viruses

Question 25

Describe the stages of genetic engineering

Answer 25

1. Select DNA you want to insert (eg gene for human insulin) + cut out with restriction enzyme. Vector DNA then cut open using same restriction enzyme
2. Vector DNA + DNA inserted have sticky ends. Mixed with ligase enzymes.
3. Ligases join DNA together to make recombinant DNA
4. Recombinant DNA (vector with new DNA) inserted into other cells
5. Cells now use gene inserted to make protein you want. Eg bacteria with human insulin gene is grown in huge numbers in a fermenter to produce insulin for diabetes.

Question 26

Benefits of genetic engineering in agriculture

Answer 26

Crops GM to be resistant to chemicals that kills plants (herbicides). Farmers can now spray crops to kill weeds only. Increases crop yield.

Question 27

Benefits of genetic engineering in medicine

Answer 27

Produce insulin. Able to transfer human genes that produce useful proteins into sheep + cows that could prevent illnesses

Question 28

Risks of genetic engineering in animals

Answer 28

Hard to predict what effect modifying its genome will have on organism. Some could suffer from health problems.

Question 29

Risks of growing genetically modified crops

Answer 29

Transplanted genes could get out into environment + herbicide resistant gene picked up by weed causing super weed.
GM crops could adversely affect food chains or human health