Topic 4 Natural Selection and Genetic Modification

Question 1

Evolution

Answer 1

Gradual change in the characteristics of a species over time

Question 2

How does evolution work?

Answer 2

Variation causes it because some organisms outcompete others due to better adaptations. Therefore they are more likely to survive due to natural selection and pass on their genes

Question 3

How does antibiotic resistance in bacteria/resistant organisms prove Darwin’s Theory of Evolution?

Answer 3

Variation exists in the population of bacteria in the body (some are more or less resistant to antibiotics)
Antibiotics kill less resistant bacteria first.
More resistant bacteria have an advantage and survive longer due to natural selection.
If course of antibiotics isn’t finished properly then the resistant bacteria start to reproduce again and advantageous characteristics are passed on

Question 4

Homo sapiens

Answer 4

Time: Present
Brain volume: 1500cm^3
Height: 180cm
Tools: flint tools, pointed tools (arrow heads), fish hooks and needles 50,000 years ago

Question 5

Homo erectus (upright man)

Answer 5

Time: 0.5 to 0.8 million years ago
Brain volume: 850cm^3
Height: 179cm
Tools: Sculpted rocks into shapes to produce tools like and axes to hunt/dig/chop/scrape meat off bones

Question 6

Homo habilis (discovered by Leakey)

Answer 6

Time: 1.6 million years ago
Brain volume: 500-600cm^3
Height: 130cm
Tools: Simple stone tools - pebble tools made by hitting rocks together

Question 7

Australopithecus afarensis

Answer 7

Time: 3.2 million years ago
Brain volume: 400cm^3
Height: 107cm
Tools: Simple stone tools - pebble tools made by hitting rocks together

Question 8

Ardipithecus ramidus (Ardi)

Answer 8

Time: 4.4 million years ago
Brain volume: 350cm^3
Height: 120cm
Tools: None

Question 9

Change in humans over time - evidence from fossils

Answer 9

Larger cranial cavity (bones don’t decay) therefore a bigger brain overtime
Humans were getting taller, found by checking bone length

Question 10

Change in humans over time - evidence from stone tools

Answer 10

Can check how deep the stone tool is in the rock layer to find the age of the tool. Deeper = older tool
Can use radioactive/carbon dating to check the age of the rocks/fossils around the tool or the actual tool
Simper tool = older tool because earlier humans had less brain volume and could only construct basic tools
More complex tools needed larger brains and were used for hunting, skinning, preparing food

Question 11

All classification groups

Answer 11

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

Question 12

Binomal name

Answer 12

Genus + species e.g Homo sapien

Question 13

5 kingdom names

Answer 13

Animals, Plants, Protist, Prokaryotes, Fungi

Question 14

Prokaryote

Answer 14

Singled-celled organisms without a nucleus

Question 15

Protist

Answer 15

Eukaryotic single-celled organisms

Question 16

Why was the Domain system created?

Answer 16

Scientists compared the sequences of DNA/RNA bases in different organisms - more similar = more closely related
More accurate than kingdoms

Question 17

All three domains

Answer 17

Archaea, Bacteria, Eukarya

Question 18

Archaea

Answer 18

Organisms in this domain look similar to bacteria but are different because of differences in their DNA/RNA sequences - found in hot springs and salt lakes

Question 19

Bacteria

Answer 19

True bacteria like E.coli

Question 20

Eukarya

Answer 20

Fungi, animals, plants, protists

Question 21

Selective breeding

Answer 21

People select features they desire in plants/animals and breed them to make another organism they desire.
Produces breeds in species

Question 22

Process of selective breeding

Answer 22

Choose male and female with desired characteristics.
Breed them.
Look at offspring and choose 2 with best characteristics and breed them together.
Repeat over several generations and eventually all offspring will have desirable offspring.

Question 23

Advantages to selective breeding

Answer 23

Increase yield/quality of harvest increased.
Plants that look more appealing can be made naturally
Higher profits for farmers
Can eliminate diseases in a species by choosing only offspring with best characteristics (resistance)
Medical research and investigation between different types of organisms in same species in behaviour.

Question 24

Disadvantages to selective breeding

Answer 24

Inbreeding causes reduction in gene pool so if a disease comes all of them would not be resistant
Genes are lost so less variation
Health problems as genetic defects are inherited
Animals made for increased yield (meat or milk) could suffer
Can’t control random mutations

Question 25

Genetic engineering

Answer 25

Process which involves modifying genome of an organism to introduce desirable characteristics

Question 26

Process of genetic engineering (in bacteria for insulin)

Answer 26

Identify the insulin gene in a human cell.
Remove insulin gene with restriction enzyme.
Remove plasmid from bacteria and use it as a vector to introduce the insulin gene.
Open up plasmid with same restriction enzyme, leaving sticky ends where the insulin gene can be introduced and use DNA ligase to seal the gene
Put plasmid back into bacteria and it will start producing insulin.
You only have to do this to one bacteria and it will reproduce

Question 27

Advantages to genetic engineering

Answer 27

Crops can be made herbicide resistant meaning farmers can spray their crops to kill weed without affecting actual crop
Bacteria can be engineered to produce insulin
Useful proteins can be genetically engineered to be produced by animals and extracted (from milk)

Question 28

Disadvantages to genetic engineering

Answer 28

Transplanted genes (for herbicide resistance) could get out into the environment and picked up by weeds, creating a superweed.
GM crops could affect food chain or human health (not much evidence)
Many GM embryos don't survive as results are difficult to predict in genetic engineering - ethical

Question 29

Vector

Answer 29

Something used to transfer DNA to a cell

Plasmid and virus