Unit 4 - Natural selection and genetic modification Flashcards
Who was Alfred Russel Wallace?
A biologist who developed the theory of speciation
Give the process of speciation
- Variation exists because of mutation
- Desirable traits are selected through natural selection, and those with desirable traits will win competition
- Over time the selection of alleles will increase the genetic variation between populations
- When these differences are so big that the populations can’t have fertile offspring
Who was Charles Darwin?
A biologist who “invented” the theory of evolution and publihed ‘on the origin of species’ - 1859
Describe the theory of evolution
- Variation exists because of mutation
- Organisms with the best traits will be more likely to survive and have offspring (survival of the fittest)
- The beneficial characteristics are carried on to the next gen
- Over time this advantageous characteristic will be more common
Why was there controversy surrounding the theory of evolution
- It contradicted the idea of a creator
- There wasn’t enough evidence to back up this claim
- It was not understood how it works
When are bacteria labelled resistant
When they aren’t killed by bacteria which previously were used as cures against them
How do bacteria develop resistance to antibiotics
- Some bacteria will naturally have resistance
- They will not be killed by antibiotics
- If those antibiotics are stopped early, only those (strong) bacteria will survive
- They will reproduce
- This is a new strain, which is resistant to antibiotics
Give an example of a bacteria that has developed resistance
MRSA
How can we find the age of fossils?
- Relative dating with fossils
- Relative dating with rocks
- Radiometric dating
What is relative dating with fossils
Comparing other similar known fossils and estimating the age
What is relative dating with rocks
Seeing how far the rocks in which the fossil is down; the further down = the older
What is Ardi
A fossil set for the oldest known human ancestor, Ardipithicus Ramidus
How old was Ardi
~4.4 million years
Ardi is ____ between apes and humans
Phenotypically
How does the bone structure of Ardi’s feet & legs suggest that it climbed trees, but could also walk upright
It had a long curved toe coming out of its foot which was used to grab onto trees
It had a bone structure in the legs that suggested it did
What is Lucy
The set of bones discovered, belonging to the species Homo Habilis
How old is Lucy
~3.2 million years
Who discovered Lucy?
Louis and Mary Leaky
How do we know Homo Habilis was a tool-user?
Lucy was discovered with remnants of stone tools
How can we estimate how smart Lucy is
It had a chimp sized skull and brain, so was likely another ‘inbetweener’ between humans and apes
What tells archaeologists that Lucy could walk upright
Her bone structure
What tools did Homo Habilis use?
Basic unsophisticated pebble tools
How did Homo Habilis create these tools?
Smashing rocks together
Give a use of the simple tools Homo Habilis used
Cracking nuts open
What tools did Homo Neanderthalensis (Neanderthals) use?
More sophisticated tools such as pointed arrowheads, spears and hooks
When didHomo Neanderthalensis (Neanderthals) use these tools
40,000 years ago
Give a use of the tools Homo Neanderthalensis (Neanderthals) used
Catching fish
How can we date the age of tools
Radiometric carbon dating (by looking at the natural radioactive decay of carbon-14)
Relative dating
What is the pentadactyl limb
A limb with 5 digits
What does the pentadactyl limb in multiple animals show us
The organisms that have this limb all have a common ancestor
Why do species branch off?
- Speciation
- Differing selection pressures
What 2 ways can we classify similar organisms into groups
- The 5 kingdoms system
- The 3 domains system
What are the 5 kingdoms?
- Animals
- Plants
- Fungi
- Prokaryotes
- Protists
After the 5 kingdoms, how are the animals subdivided?
- Phylum
- Class
- Genus
- Order
- Species
What is the binomial naming system
The naming system we use for scientific names (genus, species, e.g. Homo (Genus) Sapien (Species))
Why was the three domain system developed?
Developments in science improved like the microscope and increased knowledge of biochemistry (such as RNA sequence analysis) proved the 5 kingdom system inefficient
Who made the 3 domain system
Carl Woese
What are the 3 domains, and what seperate them
- Archaea - single cell organism, no nucleus, non-coding sections of DNA
- Bacteria - single cell organism, no nucleus, NO non-coding sections of DNA
- Eukaryota - Organisms with a nucleus
What is selective breeding
When humans choose which organisms to breed to produce offspring with a desirable characteristic
Give an example of a desirable characteristic that people may selectively breed for
Animals with more meat
How does selective breeding happen
- Parents with desirable characteristics
- They are bred
- Pick offspring with desired characteristic
- Repeat until all offspring have characteristic
What problems are there with selective breeding
- Inbreeding
- Reduction of gene pool
Why is it bad if a new disease is exposed to a selectively bred population
If the population is vulnerable to that disease they can be wiped out
What is tissue culture
The method of culturing living tissue, e.g. making it grow outside of an organism, within a growth medium
Give 3 benefits to tissue culture
- Produces alot of the offspring with a desirable feature
- Increases the number of crops resistant to bad weather
- Can help endangered species
Give 3 risks of tissue culture
- Gene pool reduced
- Clones have a low survival rate
- It may lead to human cloning
What is genetic engineering
Modifying the genome of an organism by introducing a gene from anotther organism to give a desired characteristic
Give an example of how genetic engineering has been used to benefit humans
The production of artificial insulin for diabeties treatment
What is stage 1 of making insulin
The gene for making human insulin is identified and cut out with a restriction enzyme, leading sticky ends
What is stage 2 of making insulin
A plasmid is taken from a bacterium
What is stage 3 of making insulin
The SAME restriction enzyme is used to cut open the plasmid (known as the vector) leaving sticky ends
What is stage 4 of making insulin
The human insulin gene is inserted into the plasmid
What is stage 5 of making insulin
DNA Ligase, an enzyme joins the complimentary sticky ends of together making a recombinant plasmid
What is stage 6 of making insulin
The recombinant plasmid is inserted into bacteria
Give stage 7 of making insulin
- The genetically modified bacteria are cultured in fermentered
What is stage 1 of tissue culture for plants
Take the plant you want to grow
What is stage 2 of tissue culture for plants
With tweezers remove a piece of tissue from the fast-growing region of the plant such as the root
What is stage 3 of tissue culture for plants
Using asepctic technique, place the tissue on a special growth medium (with nutrients and hormones)
What is stage 4 of tissue culture for plants
When the tissue is developed enough, transfer to compost for further growth
What are crops engineered to be resistant to
Insects
Herbicides
How can genetic modification be used in medicine
- It may be possible to cure inherited disorders
Give 3 benefits of genetic engineering
- It can be useful for medicinal use
- Crops with extra vitamins can be produced where they’re difficult to obtain
- Greater yields can help solve world hunger
Give 3 ways in which GE can be used to improve crop yields
- Improving growth rates
- Introducing mods that allow crops to grow in different conditions
- Intoducing mods that allow plants to make their own pesticides
Give 3 risks / disadvantages of GE
- GM crops can have bad effects on wild flowers and therefore insects
- People are worried we don’t understand the effects of GM on crops
- GE in agriculture could lead to GE in humans
How can we use GE to increase crop yields & profits
We can use crops that have been modified with Bacillius thuringiensis, similarly to how we make insulin. This bacteria produced toxins that kill insect larvae
How can we use fertilisers to cope with the growing demands of humans
Fertilisers provide nitrates and phosphates (useful nutrientes) to plants, which allow crops to grow faster & larger. But they can run off into rivers, killing fish.
How can we use biological control to cope witht the demands of humans
We can introduce species that would be predators to a species we want gone, which sometimes works. e.g.the aphid killer wasp has been used ot control the populations of aphids, which feeds on crops
Give 2 advantages of selective breeding
- It is possible to greatly increas the yield of a particular crop
- Individual plants / animals can be bred to be resistant to specific diseases
