Natural Selection And Genetic Modification Flashcards
What does natural selection mean
Survival of the fittest
What are selection pressures
Things that affect an organisms chance of surviving and reproducing
What are examples of selection pressures
Predation, competition for resources, disease
Why does antibiotic resistant bacteria support Darwin’s theory of evolution
It makes the bacteria better adapted to an environment in which antibiotics are present, as a result antibiotic resistance becomes more common in the population over time
What is Darwin’s theory of evolution by natural selection
If an organism develops a mutation in their dna it creates new alleles which change their characteristics, some of which can be big advantages such as bacteria being resistant to antibiotics, this organism is then better suited and adapted to the environment and better able to survive and so lives longer and reproduces passing on the specific allele for that characteristic advantage
What is a fossil
Any trace of an animal or plant that lived a long time ago
How do fossils provide evidence for evolution
It shows how species have changed and developed over billions of years
What are hominids
Human beings and their ancestors
What is an ardi and how old is she
A fossil of the species ardipithecus ramidus, 4.4 million years old
What characteristics does an ardi have
Ape-like big toe-climbed trees, long arms, short legs, brain size of a chimpanzees, walked upright and didn’t use her hands to walk
What is a Lucy and how old is she
Fossil of the species Australopithecus afarensis, 3.2 million years old
What features does a Lucy have
Arched feet more adapted to walking than climbing, arms and legs same size and apes and humans, brain slightly larger than an ardi but similar to chimp, walked upright-more efficiently that ardi
What did Richard Leakey organise
An expedition to Kenya to look for hominid fossils
What did Leakey find, what species was it and how old was it
Turkana boy, homo erectus, 1.6 million years old
Features of the Turkana boy fossil
Short arms and long legs-human like, brain size-larger than Lucy’s-human like, even better adapted to walking upright than Lucy
What stone tool did the homo habilis use
More simple tools called pebble tools, by hitting rocks together to make sharp flakes - used to scrape meat from bones or crack bones open
What stone tools did homo erectus use
Sculpted rocks into shapes to produce more complex tools like simple hand-axes - used to hunt, dig, chop and scrape meat from bones
What stone tools did the home Neanderthalensis use
More complex tools, evidence of flint tools, pointed tools and wooden spears
What tools did Homo sapiens use
Flint tools, pointed tools-arrowheads, fish hooks, needles appeared around 50,000 years ago
How old were homo habilis
2.5-1.5 million years ago
How old where the homo erectus species
2-0.3 million years ago
How old were the homo neanderthalensis
300,000-25,00 years ago
How old were the Homo sapiens
200,000 years ago
What are the 3 different ways scientists can work out how old a fossil tool is
Looking at the structural features(simpler tools=older), using stratigraphy -study of rock layers(older rock layers found under younger rock)-stones and tools found deeper in rock=older, carbon-14 dating can be used to date stone tools as they often contain carbon-containing material
What is classification
Organising living organisms into groups
How are organisms classified
On their characteristics, as technology improved, included things u can see with a microscope
What’s the system called to classify organisms
The five kingdom classification system
What are the 5 kingdoms
Animals, plants, fungi(mushrooms,yeasts,toadstools), prokaryotes, protists(eukaryotes)
What are the 5 kingdoms then subdivided into
Phylum, Class, order, family, genus, species
Who invented the three domain system
Carl Woese
What are the 3 domains
Archaea, bacteria, eukarya
Why was the 3 domain system introduced
Technology had developed further and our understanding about biochemical processes and genetics improved, we can now determine the sequence of DNA bases in organisms genes and compare them - more similar = more closely related
What is selective breeding
When humans artificially select the plants or animals that are going to breed so the genes for particular characteristics remain in the population
What are some disadvantages of selective breeding
Reduces the gene pool(no. Of different alleles in a population), inbreeding can cause health issues(more chance of the organism inheriting harmful genetic defects when the gene pool is limited), can be serious problems of a new disease appears(not much variation in the population so not many disease resistant organisms-all organisms are closely related to if 1 organism dies from a disease the rest are likely too)
What do restriction enzymes do
Recognise specific sequences of dna and cut the dna at these points - the pieces of dna are left with stick ends where they have been cut
What are ligase enzymes
Used to join 2 pieces of dna together at their sticky ends
What is recombinant dna
2 different bits of dna stuck together
What is a vector
Something that’s used to transfer dna into a cell
What are the 2 sorts of vectors
Plasmids, viruses
What are plasmids
Small, circular molecule of dna that can be transferred between bacteria
What do viruses do
Insert dna into the organisms they infect
What are the steps of genetic engineering
1) the dna u want to insert is cut out with restriction enzymes, the vector dna is then cut open using the same restriction enzyme
2) the vector dna and the dna you’re inserting are left with sticky ends. They are mixed together with ligase enzymes
3) ligases join the pieces of dna together to make recombinant dna
4) the recombinant dna is inserted into other cells
5) these cells can now use the gene u inserted to make the protein u want
Why is genetic engineering useful in agriculture
Crops can be genetically modified to be resistant to herbicides
Why is genetic engineering useful in medicine
Genetically engineered bacteria can produce insulin, human genes can be transferred into animals to produce useful proteins
What is the disadvantage of genetic engineering of animals
It’s hard to predict what effect modifying its genome will have on the organism
What is the concern of genetically modified crops
The transplanted genes may get out into the environment and may make weeds herbicide resistant, they could affect food chains or human health
What is genetic engineering
A process which involves modifying the genome of an organism to introduce desirable characteristics
What are the advantages of selective breeding for agriculture
Genetic variation means some cattle will have better characteristics and produce more meat
Why is selective breeding used in medical research
Using rats can investigate the reason behind alcoholism, rats with strain and weak preferences for alcohol are bred to compare the differences between the 2 different types of rats and the way their brains work
