⭐️SB4 - Natural Selection And Genetic Modification Flashcards
What is evolution?
The gradual change in the characteristics of a species over time
How has skull volume changed with human evolution?
It has increased
Name the most recent human like species
Homo erectus
How can you differentiate between an older stone tool and a newer one?
Older ones are more simple but newer ones are more pointy with sharper details and edges
What is genetic variation?
Where the characteristics of individuals vary due to differences in genes
What are the stages in Darwin’s theory of evolution?
- There’s variation in a species
- Environmental change : There becomes competition for food/space/mates
- Natural selection: The better adapted members survive
- inheritance: Survivors pass on the beneficial genes to their offspring
- Evolution: Beneficial characteristic increases in a population over time
What is a common ancestor?
The animal that two different animals have evolved from
What can cause bacteria to form an antibiotic resistantce
Natural selection and evolution as they evolve to become able to survive antibiotics
Describe the stages of bacteria developing an antibiotic resistance
- Bacteria in a population already show variation (some are more resistant than others)
- When antibiotic course begins, more and more bacteria are killed and the resistant ones take the longest to die
- The course of antibiotics is finished to early leaving more resistant bacteria still alive
- These bacteria then reproduce and the new population are all resistant to the antibiotic
What causes resistance to develop in a species of bacterium?
Stopping antibiotics too early
Why did Darwin take time to produce his evidence?
As he knew his theory was controversial as it went against religious ideas of that time
Why was the evolution of characteristics in fossils not gradual?
Because there was a lack of fossil dicivert
Describe Wallace’s role in developing the theory of evolution by natural selection [2]
Wallace provided evidence for natural selection [1] and worked with Darwin to develop the theory [1]
How did Darwin come up with the idea of natural selection?
He studied birds in the Galápagos Islands and took them back to London to study them, he also read an essay by Thomas Malthus giving him the idea that organisms produce more offspring than can survive and only those with best suited characteristics will continue
How does the pentadactyl limb provide evidence for evolution?
Many species have a pentedactyl limb that all have different uses. This provides evidence that species with a pentedactyl limb have evolved from a common ancestor and that the bones have not been designed for a specific purpose among each species
Why aren’t the five kingdoms organised based on characteristics?
Because of evolution, some organisms have evolved similar characteristics but are not closely related
How did scientists alter the five kingdoms so they weren’t classified based on characteristics?
By making sure each organism in each group had evolved from a recent common ancestor
Name each of the five kingdoms
Animals, plants, fungi, protists and prokaryotes
What’re the main characteristics of animals
They are multicellular (cells arranged in tissues and organs) the cells have nucleus and no cell walls
Give the main characteristics of plants
Multicellular, have chloroplasts for photosynthesise cells have nuclei, cellulose cell walls
Give the main characteristics of fungi
Multicellular (except yeasts), live in dead matter, cells have nuclei, cell walls contain chitin instead of cellulose
Give the main characteristics of protists
Mostly unicellular, cells have nuclei, some have cell walls made of various substances (not chitin)
Give the main characteristics of prokaryotes
Unicellular, cells have no nuclei, cell walls are flexible
What did the development of genetic analysis show in terms of unused dna?
All organisms except prokaryotes have unused sections of dna
State the three domains organisms should be divided into
Archaea, bacteria and eukarya
State the characteristics of archea
Cells with no nucleus, genes contain unused sections of dna
State the characteristics of bacteria
Cells with no nucleus, no unused sections in genes
State the characteristics of eukarya
Cells with a nucleus, there are unused sections in genes
What domain of classification do animals, plants and fungi fit into?
Eukarya
Explain how looking at changes in dna is beneficial to scientists?
As they can work out how closely related two organisms are. This is because the more dna two organisms have in common, the more recently they evolved from a common ancestor and the more closely related they are
How did scientists come to more conclusions on archea genes? What were these conclusions?
Through genetic analysis, they realised archea genes are more similar to plant and animal genes than to prokaryotic genes as archea genes were found to have unused sections of dna
What is artificial selection?
When humans choose certain organisms because they have useful characteristics
What is selective breeding?
When humans choose an organism that has certain characteristic and breeding more of these organisms making that chosen characteristic more obvious
Why are plants and animals selectively bred?
To increase disease resistance To increase yeild To cope with certain environmental conditions Faster growth A certain flavour
What ways can we create new breeds and varieties?
Genetic engineering, selective breeding and artificial selection
What happens in genetic engineering?
Where the DNA of an organism is changed by inserting into it genes from another
Why may someone choose genetic engineering over artificial selection? What’s the downside?
It’s much faster however costs more
Why do we genetically engineer organisms?
As we can make them resistant to diseases, make them grow much faster, in crops, improve their health benefits and create organs for transplants
What is tissue culture?
The growing of cells or tissues in a liquid containing nutrients or on a solid medium (e.g. nutrient agar)
What is a callus?
A clump of undifferentiated cells
What can tissue culture be used for in plants?
To create plants of vary rare species at risk of extinction, to clone gm plants, to grow plants that are hard to grow from a seed.
What are the steps to carrying out tissue culture in a plant without creating a callus?
- A piece of plant is sterilised in bleach solution
- A small piece of the plant is cut of and placed on sterile nutrient agar to grow
- The plant piece is treated with hormones so it grows roots and shoot.
- Once large enough, the plant is put into soil or compost
What are the steps to carrying out tissue culture in a plant by producing a callus?
- Plant is sterilised with solution
- A few cells are cut off and placed in sterile nutrient medium to grow into a callus
- Callus is treated with hormones so the plant lets develop with shoots and roots
- The plantlets are separated and grown on a nutrient medium in sterile conditions
- Once large enough, the plant is placed into compost or soil
What are the uses of tissue culture in medicine?
- to study how cells communicate to each other by culturing a thin layer of cells on a solid medium
- to study viruses that can’t replicate outside of cells
- to study how cancers develop and spread
- to investigate how infected cells respond to new medicine without risking harm to humans or animals
- to create organs that could be used for transplants
What is a pest?
An organism that damages the yield of a crop
How can insect pests be controlled?
By spraying the crop with insecticides
Give a disadvantage of insecticides?
They only kill the insect when it touches it and you need different insecticides for different insects
What produces Bt toxin? what is it?
A soil bacterium and and is a natural insecticide protein
How were plants genetically modified to produce the Bt toxin?
By having the genes that control the production of the insecticide in the bacterium be inserted into plants
Give some advantages of GM plants that produce their own insecticides
- The crops themselves become resistant to pests
- only pests that chew the plants are affected as that’s what breaks the cells and releases the chemical. This means insect predators like ladybirds are unharmed
- increase the yield of the crops
Give some disadvantages of GM crops
- Farmers may still need to spray crops to remove pests that don’t actually chew the plant like aphids
- insects can become resistant to the toxins
- GM crop seeds are more expensive
- some are concerned GM foods could harm their health
How can insect resistance to insecticides from GM Plants be overcome
The GM crop can be developed to replace the varieties that pests are resistant to.
What are the disadvantages of selective breeding?
- Only certain alleles are selected, others that could become rare or disappeared, making alleles that may be needed in the future not available
- organisms will also all be similar and lack much variation making them more likely to all be effected by a change in environment
Why is insulin extracted from bacteria instead of pigs?
As gm bacteria is cheaper and suitable for vegans or people who don’t eat pork for religious reasons
Give the steps involved in genetic engineering of bacteria to produce insulin
- A section of human dna containing the insulin making gene is cut using restriction enzymes which make staggered cuts in the dna molecule leaving unpaired bases at each end called sticky ends.
- The same restriction enzymes are then used to cut plasmids so that they are left with the same sticky ends
- Sections of dna containing the insulin gene are mixed with the cut plasmids so the complimentary bases on the sticky ends pair up. These are joined with the enzyme ligase
- The plasmids are inserted back into the bacteria where they are grown in huge tanks so the insulin they make can be easily extracted
What is the vector in the process of genetically engineering bacteria to produce insulin?
The dna molecule used to carry new DNA into another cell
What is the role of fertilisers?
They speed up and improve plant/crop growth by replacing nutrients in the soil
What’s biological control ?
Releasing organisms into a controlled area to kill pests and eradicate them
Give an advantage of pesticides
They are cheap
Give 2 advantages of fertilisers
They can increase the yield and growth
They make healthy new cells in the plant
Give 2 disadvantages of fertilisers
They can pollute lakes and rivers
They can cause health issues for humans and animals If they drink water polluted by the fertilisers
Give 4 advantages of biological control
It can control weeds
They can increase the yield
They are self sustainable
It means pests can be eradicated by another organism eating them rather than using external chemicals
Give 4 disadvantages of biological control
It can take some time to be effective
It can be expensive depending
on the type of biological control used
The predator may not stay in the area needed
Removing a pest could cause knock on issues in the ecosystem
