B17 Evolution (not quite finished) Flashcards
evolution
the gradual change in the inherited characteristics of a population over time
- occurs through process of natural selection
process of natural selection
- there will randomly mutations in a population (leading to variation)
- some traits are more favourable a- individuals with these traits are more likely to survive & reproduce
- in the next generation, a relatively higher proportion of the population have these traits
- over many generations, this can lead to evolution
what did Charles Darwin do
proposes theory of evolution by natural selection - states that all living species evolved from a common ancestor that first developed over 3B years ago
why were darwin’s ideas controversial
they challenged the idea that god made all of the earths animals and plants
insufficient evidence at the time
mechanisms of inheritance and variation were not known
there were other theories (Jean-Baptiste Lamarck - “inheritance of acquired characteristics” - changes that occur over an organisms lifetime are passed on to offspring - we now know this can’t happen)
evidence of evolution
shown that characteristics are passed on to offspring in genes
evidence from the fossil record
evolution of antibiotic resistance in bacteria
speciation (definition + who came up with it)
gradual for mario of a new species as a result of evolution
Alfred Russel Wallace (who also independently proposed theory of evolution by natural selection)
speciation process
1) two populations of one species are isolated (river, mountain range etc)
2) natural selection occurs so better adapted individuals survive/reproduce and pass on these characteristics
3. the populations have an increasing number of genetic mutations as they adapt to their different environments
4. eventually the two populations are so genetically different they can’t breed together to produce fertile offspring
extinction
when there are no remaining individuals of a species still alive
factors causing extinction
new predators
new diseases/pathogens
increased competition
catastrophic events (asteroid impacts, volcanic eruptions, earthquakes)
changes to the environment (climate change, destruction of habitats)
fossilisation process
- organism dies and falls to the ground
- flesh decays, leaving skeleton covered in sand/soil/clay before it is damaged
- protected, over 10000000s of years skeleton becomes mineralised and turns to rock. rocks shift in the earth with the fossil trapped inside
- eventually the fossil emerges as rocks move and erosion takes place
fossil (and what are they formed from?)
remains of organisms from millions of years ago, found in rocks
formed from:
parts of an organism that do not decay
hard parts (eg bones) when replaced by minerals
preservation of the traces of organisms (eg burrows, footprints, rootlet traces)
why is the fossil record good
- can tell scientists how individual species have changed over time
- fossils allow us to understand how life developed over earth’s history
- fossils can be used to track the movement of a species or its ancestors across the world
problems with the fossil record
many early organisms were softbodied - so most decayed before producing fossils (only hard materials mineralise)
geological activity (volcanic activity, erosion, mountains forming) contributed to loss of fossils.
Linnaeus’ system of classification
kingdom
phylum
class
order
family
genus
species
(king phillip came over for good soup)
how are organisms named
binomial system of genus and species
three-domain system
developed by Carl Woese
higher level of classification called a domain
divides organisms into:
archaea - primitive bacteria (including extremophiles that can live in extreme conditions)
has one kingdom - archaebacteria
bacteria - true bacteria + cyanobacteria which can photosynthesise.
has one kingdom - eubacteria
eukaryota - all have cells that contain a nucleus enclosing the genetic information
four kingdoms - protista, fungi, plants, animals
evolutionary trees (purpose)
can be drawn to show relationships between different groups of organisms
why can new pathogens spread rapidly
people are not immune to it
there is no effective treatment
antibiotic resistance
bacteria reproduce v quickly - evolve rapidly
when antibiotics are used, some bacteria survive
these have (through mutation) antibiotic resistance
these bacteria reproduce, increasing the population of resistant bacteria
over time, the whole population become descended from the antiobiotic-resistant bacteria (MRSA)
how to deal with antibiotic resistance (not just for humans)
can’t keep up by developing new antibiotics - expensive and slow
so:
doctors should only prescribe antibiotics for serious bacterial infections
patients should complete their course of antibiotics so all bacteria are killed and none survive to form resistant strains
use of antibiotics in farming and agriculture should be restricted
species
organisms that can breed to produce fertile offspring
exam question! (hard)
overfishing in the north sea significantly depleted fish stocks. so the government made it so large mesh fishing nets with larger holes had to be used.
explain why? (3)
large holes allow small fish to escape
which allows them to grow large enough to reproduce
replacing larger fish caught for human consumption / so
fish population remains constant
exam question!
overfishing in the north sea significantly depleted fish stocks. so the government made it so large mesh fishing nets with larger holes had to be used.
fish species started to breed even when they were still small.
explain why (6)
