natural selection and genetic modification Flashcards
topic 4
explain Charles Darwin’s theory of evolution by natural selection
- individuals in a population show genetic variation due to differences in their alleles
- predation and competition for resources and disease act as selection pressures
- better adapted characteristic to the selection pressures in their environment give the individuals a better chance of survival
- breed successfully and alleles (+genes) are passed on
- organisms evolve
Explain how the emergence of resistant organisms supports
Charles Darwin’s theory of evolution including antibiotic
resistance in bacteria
- makes the bacteria better adapted to an environment
- where antibiotics (selection pressure) are present
- so antibiotic resistance becomes more common in the population over time
another example of a resistant organism
rats resistant to poison
what is a selection pressure
- something that affects an organisms chance of surviving and reproducing
- ex predation, competition, disease
- some bacteria in population are more resistant to antibiotics
- antibiotic is added to the population of bacteria (selection pressure)
- some survive
- survivors reproduce and pass on resistant alleles/genes
describe the evidence for human evolution based on fossils
a) Ardi from 4.4 million years ago
- big toe to climb trees
- long arms and short legs
- brain size like a chimpanzees
- structure of legs = walked upright
- structure of hand bones = didn’t use hands to walk
describe the evidence for human evolution based on fossils-
b) Lucy from 3.2 million years ago
- arched feet for walking not climbing
- no ape like big toe
- size of arms and legs between an apes and a humans
- brain slightly larger than Ardi’s - still similar to a chimps brain
- structure of leg bones and feet = walked upright and more efficiently to Ardi
describe the evidence for human evolution based on fossils
c) Richard Leakey’s discovery of fossils from 1.6 million years ago
found fossils of homo erectus
- short arms and long legs = more human
- larger brain size and more similar to humans that Lucy’s
- structure of legs and feet = better at walking upright than lucy
who came first Ardi or Lucy or Homo erectus
oldest = Ardi
middles = Lucy
youngest = homo erectus
describe the evidence for human evolution based on stone tools
a) the development of stone tools over time => HOMO HABILIS (1)
- simple stone tools by hitting rocks together
- could scrape meat from bones or crack bones open
describe the evidence for human evolution based on stone tools
a) the development of stone tools over time =>
HOMO ERECTUS (2)
- sculpted rock s into shapes
- more complex
- hunt dig chop scrape meat
describe the evidence for human evolution based on stone tools
a) the development of stone tools over time =>
HOMO NEANDERTHALENSIS (3)
- more complex
- flint tools, pointed tools and wooden spears
describe the evidence for human evolution based on stone tools
a) the development of stone tools over time =>
HOMO SAPIENS
- flint tools
- pointed tools including arrow heads, fish hooks and needles
describe the evidence for human evolution based on stone tools
b) how these can be dated from their environment
- looking at structural features - simpler likely to be older
- stratigraphy - study of rock layers - older rock layers found below younger layers (tools or fossils found in deeper layers = older)
- carbon-containing material - Carbon-14 dating used to date the material
Describe how genetic analysis has led to the suggestion of the three domains rather than the five kingdoms classification method
- technology developed
- Woese found that some members of Prokaryote Kingdom were not as closest related using genetic analysis
- he suggested all organisms divided into 3 groups “domains” = archaea, bacteria, eukarya
- then the 3 domains are split into smaller groups used in the five kingdom system
what are the 5 kingdom domains
- animals
- plants
- fungi
- prokaryotes
- protists
and then split into smaller groups - phylum, class, order , family, genus, SPECIES
what are the 3 domains
- archaea
- bacteria
- eukarya
explain selective breeding
- select characteristics you want from existing stock
- breed them with each other
- select best offspring and breed them together
- continue over several generations - eventually all offspring will have the characteristic
explain selective breeding’s impact on food, plants and domesticated animals (disadvantages of selected breeding)
- reduces the gene pool of alleles ( number of different alleles
- inbreeding can cause health problems
- little variation is bad for if a new disease appears
explain how selective breeding reduces the gene pool
- reduces number of different alleles
- as the “best” animals or plants are used for breeding - and are closely related
- = inbreeding
how does inbreeding cause health problems
- there’s more chance of organisms inheriting harmful genetic defects when the gene pool is limited
how does selective breeding cause serious health problems if a new disease appears
- not much variation so less chance of resistance alleles being present
- all stock are closely related to each other
- so if one dies to disease they likely will all die
advantages of selective breeding in agriculture
- genetic variation means some cattl ehave better characteristics for proudcing meat
- to improve meat the farmer may breed best cows together
- to get the best offspring
advantages of selective breeding in medical research
- investigating reasons behind alcoholism
- rats bred with strong or weak preference to alcohol
- researchers compare differences in the rats like behaviour and way their brains work
