Unit 4 - Natural Selection And Genetic Modification Flashcards
What is evolution
To gradual change in characteristics of a species over time
Why do you fossils is not show smooth changes over time
Because not all have been discovered
What is the name of the most complete set of fossils
Ardi
What species is Ardi from
Ardipithecus ramidus
Give three characteristics of Ardi
About 1.2 m tall, very long arms, may have been able to walk right
What species is Lucy
Australopithecus afarensis
What is the species name for modern humans
Homo sapiens
What species did Homo sapiens evolve from
Homo neanderthalensis
How can scientists work out the ages of stone tools
Using the different layers of rock. The stone tool is about the same age as the layer of rock
What could the oldest stone tools be used for
Skinning an animal or cutting up meat
Which two scientists came up with the idea of evolution
Charles Darwin and Alfred Russell Wallace
What does genetic variation mean
When the characteristics of individuals vary
What is environmental change
When conditions in an area change. For example, the lack of resaws such as food
What is natural selection
Sometimes the variations of some individuals make them better at coping with changes and are more likely to survive
How does evolution happen
If the environmental conditions remain changed, natural selection occurs over and over again, and a new species evolve with all the individuals having the better adapted variations
Given examples of how a species could have evolved
The environment could be getting cold so for some animals who may have been hairier would have survived against the cold. These animals would have bred and overtime the animals became hairier and hairier forming a new species
What was warfarin used for
Poison rats
How did the rats become resistant to warfarin
Due to genetic variation they had always been rats that were resistant. As the poison killed the non-resistant, the only ones left to breed were resistant
Give two examples where species had become resistant to poisons
Rats to warfarin and bacteria to antibiotics
How can stopping an antibiotic early develop a species resistant to the antibiotic
Some bacteria would be more resistant to the antibiotic. When the antibiotic course is started, the less resistant bacteria are killed. If the course is finished early, the more resistant bacteria would still be alive and would also breed. This creates a new population of bacteria that are resistant to the antibiotic
Why did scientists used to think that the Earth species could not evolve
They thought that God had created all of species and their characteristics could not change
How did Darwin begin to think about evolution
He noticed differences between mockingbirds on different islands and wondered whether a species could change form if it moved into a different area
What explanation did Darwin have for evolution
Organisms normally produce more of offspring than what could survive. Only the individuals best suited to the surroundings would survive and reproduce to pass on their characteristics
What organisms had Wallace studied
The tiger beatles, he noticed that in Indonesia they were different colours depending on where they live to camouflage them. Natural selection allowed him to explain it
What is a pentadactyl limb
A limb with five fingers
What does the pentadactyl limb suggest
There was evolution from a common ancestor and not that all bones were designed for specific purposes independently of one another
What is classification
Dividing organisms into groups based on what they look like
What the 5 kingdoms
Animals, plants, fungi, protists and prokaryotes
What does the last group contain of classification
One type of organism
How did Lennaeus give each organism binomial name
Using the two last groups, genus and species
Why might there be problems using characteristics for classification
Some organisms have evolved similar characteristics but are not closely related
How did modern scientist alter the classification system
They made it so that the smaller groups contained organisms that have evolved from recent common ancestors
What is Archaea?
A group found in the prokaryote kingdom where the organisms are single celled that have no nuclei
What is the three domain system of classification
This was created by call roads and all organisms should be divided into archaea bacteria, eukarya.
How can you tell how closely related organisms are
The more DNA two organisms have in common, the more recently they evolved from a common ancestor so the more closely related they are
What is natural selection
When by chance, some individuals inherit characteristics that allows them to survive better than others in a certain area
What is artificial selection
When humans choose organisms because they have useful characteristics, such as sheep with thick wool
What is selective breeding
When people bred organisms that have useful characteristics to humans. This results in offsprings that inherit the characteristics so by repeating this process, you would eventually get organisms with the most useful characteristics
What is selective breeding used today for
To produce new breeds of animals and new varieties of plants species
Give two examples of how people have used selective breeding
When farmers selectively bred wild wheat plants. When people selectively bred hairier sheep
Give five reasons why plants and animals are often selectively bred
Disease resistance, yield (quantity), coping with certain environmental conditions, fast growth, flavour
What is genetic engineering
Changing the DNA of an organism, it’s genome, often by inserting genes from another which creates genetically modified organisms
Give a positive and negative of genetic engineering compared to selective breeding
Positive: much faster
Negative: much more expensive
Give an example of a GMO and why it is useful to humans
Golden rice which has two jeans inserted into it Gino, one from a daffodil and one from a bacteria. It makes the rice produce beta-carotene in its grains. This makes vitamin A to stop the cause of blindness
Why are GMO is used today
Resistant to disease causing organisms
In goats and sheep, to produce proteins in their milk that can treat human diseases
GM pigs with human like organs to use in organ transplants
Salmon that grow much faster
What is tissue culture
The growing of cells all tissues in a liquid containing nutrients or on a solid medium
What is a callus
A clump of undifferentiated cells
What is tissue culture used for
To produce new plants of very rare species which are at risk of extinction
To produce new individuals of plant species that may be difficult to grow from seed
To produce clones of GM plants
Why are some undifferentiated cells in a callus treated
To make them differentiate, to become specialised
Give the steps of tissue culture
A piece of plant in placed in bleach solution to sterilise it
Only a few cells are cut off and placed on sterile nutrient medium to grow into a callus
The callus is treated with hormones so that the plantlets develop with shoots and roots
The plantlets are separated and grown on nutrient medium in sterile conditions
When the plants are large enough they are planted into soil or compost
Why is tissue culture used in medicine
Cutting a thin-layer of cells makes it easier to study how the cells communicate with each other
To study for viruses which cannot replicate outside of cells
To study how cancer spreads
How infected cells respond to new medicines without receiving harm to animals or humans
What are alleles
The different forms of genes
What happens to alleles during selective breeding
Certain alleles are selected however others become rare or disappear. This means that alleles that might be useful in the future are no longer available
Give some negatives of selective breeding
If a change in a condition occurs, all organisms are affected. For example a new disease
Animal welfare. For example some selectively bred chickens produce so much breast meat they can hardly stand up
Why have GM crops been produced
To be resistant to some insects so less insecticide is needed
To be resistant to certain herbicides so it kills weeds but not the crop
What might happen if GM plants reproduce with wild plant varieties
The genes may have unknown consequences in wild plants
State a benefit of golden rice
It produces vitamin a which helps with the cause of blindness
Why might GM bacteria be produced
To produce useful substances such as insulin
Give a positive and negative about insulin produced by GM bacteria
It is cheaper and suitable for vegans or religious people
It is slightly different to insulin from mammals so not all diabetics can use it
State the process of genetic engineering of bacteria
Restriction enzymes makes staggered cuts in DNA molecules, containing the gene, producing sections with a few unpaired bases at each end called sticky ends
Restriction enzymes also cut plasmids in the same way so they also have sticky ends
The sections of DNA or mixed with the cut plasmids. The complimentary bases on the sticky ends are paired up and an enzyme called ligase is you used to join the ends together
The plasmids are inserted back into bacteria which of then grown in huge tanks
What are plasmids
Small circles of DNA found in a bacterium
What is recombinant DNA
When DNA is combined in a new way
What is a vector
A DNA molecule used to carry new DNA into another cell
What is the yield
The amount of the crop we can use
What is Bt toxin
A natural insecticide protein
Give an advantage of GM Bt toxin
It only affects insects that chew on the plant tissues so insect predators are not harmed for example ladybirds
Why might other pests not be affected by Bt toxin
Aphids suck sap from the plant but do not chew the plant tissue
Why is having different varieties of Bt toxin bacteria a positive
When the pests develop resistance to the toxin the GM crop plants can be developed in the new varieties
What is biological control
Using organisms to control pests
Give an example of biological control
Using Weaver and nests as they remove some insect pests
What are fertilisers
Chemical compounds use to increase food production
How can pollution be caused by fertilisers
If not all of the fertiliser is absorbed by a crop some make it into a nearby stream, lake or river
What impact can water pollution have on other organisms
It can lead to the death of organisms in the water and also cause health problems for humans and animals if they drink the water
