Topic 4 - Natural selection and genetic modification

Question 1

Describe role of Darwin in development of theory of evolution by natural selection

Answer 1

• Studied variety of organisms whilst travelling around world on HMS beagle
• Noted traits can be passed from parents to offspring
• Proposed idea of ‘survival of the fittest’
• Established theory of natural selectin and published his ideas in ‘On the Origin of Species’

Question 2

Describe role of Wallace in development of theory of evolution by natural selection

Answer 2

• Proposed theory of natural selection that was similar to Darwin’s, although mechanisms were different
• Gathered greater evidence (e.g. studying warning colouration in butterflies) to support theory

Question 3

Outline the theory of natural selection

Answer 3

• Genetic mutation results in variation in the population
• Selection pressure is … (e.g. competition, disease)
• Selection pressure favours individuals with the advantageous allele
• Individuals with the advantageous allele survive, preproduce, and pass on the allele to their offspring
• Increasing allele frequency

Question 4

Describe how antibiotic resistance in bacteria can be used as example to illustrate process of evolution

Answer 4

• Genetic mutation results in variation in the population
• Selection pressure is use of antibiotics
• Selection pressure favours individuals with the advantageous allele (in this case the allele for antiniotic resistance)
• Individuals with the advantageous allele are able to survive, reproduce and pass on the allele to their offspring
• Increasing allele frequency in the population over time

Question 5

What fossils provided evidence for human evolution

Answer 5

• Ardi - 4.4 million years old
• Lucy - 3.2 million years old
• Turkana boy - 1.6 million years old

Question 6

Explain how the study of human fossils provides proof for evolution

(6 marks)

Answer 6

• Oldest known human fossil is Ardi, dating back 4.4 million years ago. Could probably walk upright but had longer arms to move through trees, brain volume of 350cm³
• Lucy is another fossil dating back ti 3.2 million years ago. Could walk upright and had feet more similar to modern humans compared to Ardi. Brain volume of 400 cm³
• Turkana boy is another fossil dating vack to 1.6 million years ago. Has larger brain volume compared to Ardi and Lucy. Brain volume of 850 cm³
• Comparison of fossils indicates how humans changed over time

Question 7

Describe the evidence for human evolution based on stone tools

Answer 7

Age of tools
* Location in rock layer - younger rock layers towards top, older rock layers deeper
* Rocks and substrate in which tools were found can be dated by radiometric dating
* Tools can be compared with age of fossils found in location
Quality of tools
* Tools become more sophisticated/more specialised with time
Skills and intelligence
* Tools show greater human skill/ more complex manufacturing
* Higher intelligence in more recent species of humans

Question 8

Describe how the anatomy of the pentadactyl limb provides scientists with evidence for evolution

Answer 8

• Many vertebrates have a pentadactyl limb including humans
• They all have similar bone structure
• The pentadactyl limb has 5 digits
• It has wrist bones - carpels, one upper limb bone - humerus, and two lower limb bones - ulna and radius
• This suggests that. they evolved from a common ancestor but adapted for different functions and that mutations resulted in different features favoured by different envirnoments
• For example, a bat has an extended first digit to support wing and horses have reduced/missing digits

Question 9

What is speciation

Answer 9

Speciation is the formation of a new species - two populations of the same species have become reproductively isolated and are no longer able to interbreed to produce fertile offspring

Question 10

What is a species

Answer 10

Organisims that can interbreed to produce fertile offspring

Question 11

What are the two types of speciation

Answer 11

Sympatric - No geographical barrier
Allopatric - There is a geographical barrier

Question 12

What is classification

Answer 12

Organisation of organisms into groups

Question 13

Name the 5 kingdoms

Answer 13

• Animals
• Plants
• Fungi
• Protists
• Prokaryotes

Question 14

Organisims used to be grouped based on similarities and differences in their anatomy and behaviour, what is the problem with this

Answer 14

• Organisims that are not closely related may look alike and behave similarly if they live in same environment e.g. sharks and dolphins
• Some closely related species may look very different if they live in different habitats e.g. queen ants, worker ants

Question 15

What advancements in science have led to scientists to reconsider five kingdoms classification system

Answer 15

• Microscopes
• Biochemistry
• DNA and RNA analysis

Question 16

Describe the three domains system of classification

Answer 16

Organisms are initially divided into extra three group: Archaea, Bacteriam Eukarya

Question 17

What are the 5 classification groups and what organisims are in them? What are the 2 features of an organisims scientific name?

Answer 17

• Kingdom - animal
• Phylum - chordate
• Class - mammal
• Order - primate
• Family - hominid
• Genus and Species

King Phillip Came Over For Great Sea

Question 18

Which domain do eukaryotic organisims belong to

Answer 18

Eukarya

Question 19

What domains do prokaryotic organisims belong to

Answer 19

Archaea and Bacteria

Question 20

What is selective breeding

Answer 20

Process by which humans artificially select organisms with desirable characteristics and breed them to produce offspring with similar phenotypes

Question 21

Outline main steps involved in selective breeding

Answer 21

• Select and breed together parents with desired characteristics
• Select offspring that have desired characteristics and breed them
• Repeat over several generations until all offspring have desired characteristics

Question 22

What are the positive impacts of selective breeding

Answer 22

Plants
* Improved crop yield
* Improved disease resistance
* Large or unusual flowers
Animals
* Improved quality of meat
* Increased milk production
* Increased meat production
* Sociable domesticated animals
* Large eggs

Question 23

What are the negative impacts of selective breeding

Answer 23

• Lack of genetic variation; if there is selection pressure, species becomes susceptible - endangered or extinct
• Lack of genetic variation would restrict ability to produce new varieties in future, species will not evolve
• Inbreeding can lead to genetic defects or susceptibility to disease (inbreeding depression)

Question 24

What is tissue culture

Answer 24

Growth of tissues or cells seperate from an animal or plant

Question 25

What is the method for tissue culture

Answer 25

* Tissue sample is scraped from parent plant * Tissue sample is placed in agar growth medium containing nutrents and auxins * Samples develop into tiny plantlets * Plantlets are planted into compost

Question 26

What are advantages of growing plants by using tissue culture

Answer 26

* Fast and simple process * Requires little space * Enables growth of many plant clones with same desirable characteristics * Useful in preservation of endangered plant species

Question 27

What are advantages of anumal tissue culturing

Answer 27

* Useful in preparation of tissue samples for medical research * Enables investigation of how different factors may affect specific animal tissue without harming animal itself

Question 28

Describe how animal tissue cultures are prepared

Answer 28

* Extract sample of tissue from animal * Use enzymes to seperate cells within sample * Grow in culture vessel containing growth medium * Once grown, store sample

Question 29

What is genetic engineering

Answer 29

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

Question 30

What is the process of genetic engineering

Answer 30

* Cut out gene of interest using restriction enzyme * Cut open plasmid using same restriction enzyme to prodice complementary sticky ends * Use DNA ligase to insert gene of interest into plasmid * Uptake of plasmid by organism and gene expression

Question 31

What are advantages of genetic engineering to produce GM organisms

Answer 31

* Crop produces toxin that kills insects so increased crop yield (in bacillus thuringiensis) * Useful in medicine * GM crops produce scarce resources

Question 32

What are disadvantages of genetic engineering

Answer 32

* Cross pollination with other plants (species), produce weeds that grow out of control * GM seeds are expensive, not all farmers can afford them * Concerns about possible effects on health * Ethical concerns - is it right to move genes between species?

Question 33

What are agricultural methods of increasing food production

Answer 33

* Intensive farming - use of fertilisers * Biological control

Question 34

What are methods of intensive farming

Answer 34

Herbicide spray - removes competing plants and weeds from growing area. (increased crop yield) However reduces biodiversity and has harmful effects on health Pesticide spray - Removes pests that feed on crops ( Increased crop yield ) However reduces biodiversity and pests may become resistant

Question 35

What is biological control

Answer 35

Using predators to control pests

Question 36

What are advantages of biological control

Answer 36

* Doesn't use pesticides preventing pests from becoming resistant * Specific to pests so other beneficial organisms not affected

Question 37

What is disadvantages of using biological control

Answer 37

Risk of predator becoming pest itself