B5.2 Flashcards
What is evolution?
Evolution is the gradual change in inherited characteristics of a population over time, through the process of natural selection, which may result in the formation of a new species
How does natural selection effect phenotypes?
It’s increases advantageous phenotypes
How much genetic variation do populations of species show?
They show a lot of genetic variation, which means that there is a big mix of genetic variants (alleles) present in the population
How do variants (different alleles)arise?
When a DNA randomly mutates (and also sexual reproduction)
What does it mean by survival of the fittest
The resources living things need to survive are limited so individuals must compete for these resources to survive.
Describe the process of Natural Selection:
- organisms in a species show variation so these is a large mixture of gene variants/alleles present
- organisms with characteristics that are best adapted to the environment survive and reproduce. Others die.
- genes from successful organisms are passed to offspring in next generation so the offspring is more likely to possess characteristics that made their parents successful ( they have advantageous phenotype and more chances of breeding and passing on genes)
- greater proportion of individuals in next generation inherit the advantageous variants and so they have the phenotype to survive
- process repeated many times and after generations, characteristics increasing survival are more common and naturally selected = development of new species
What does the speed at which species evolve depend on?
It depends partly on how quickly it reproduces such as bacteria which reproduce in just 20 mins, whereas humans are more likely to reproduce after 20 - 30 years
What does it means if an organism if quick to reproduce?
- inherited characteristics are passed on to future generations more quickly
- time taken for the population to adapt to its environment is reduced
- we can monitor evolution as it’s occurring as it’s so fast = scientists can study evolution in action
- observe how advantageous characteristics (antibiotic resistance) become more common in population
How influence does evolution have on the phenotype?
Evolution can mean that a species’ phenotype changes so much that a new species is formed
What does it mean by a new species
The old and new version of the species can’t breed together to produce fertile offspring
How can a new species be formed?
- physical barrier separates two population of species
- conditions on each side of the barriers will be slightly different so the phenotype that are beneficial will be different for each population
- natural selection acts on each population to increase the proportion of advantageous phenotype
- until population are so different they can no longer breed together
Describe the evolution of peppered moths:
- before 19th cent = moths in Britain were plain coloured (camouflage against trees)
- mutations occurred in some mothers = dark coloured = more likely to be eaten by birds
- Industrial Revolution = trees covered in soot = black moths camouflaged = more of them survived
- after several years = dark pepper moths = more common in urban areas
Describe the evolution of antibiotic - resistant bacteria
- evolve in short time = rapid reproduction
- mutations can occur kill bacterium or to make it antibiotic resistant causing new variants and alleles to be introduced into the population
- bacterium reproduce and pass it on to offspring while antibiotics kill non resistant bacteria
- may result in whole species becoming antibiotic resistant
- scientists can observe this
What do scientists think we evolve from?
- complex organism evolved from simple ones around 3500 million years ago
- fossil records and antibiotic resistance in bacteria = evidence
What are fossils?
Any trace of an animal or plant that lived long ago. They are most commonly mineralised (changed into rocks)
What can fossils tell us?
- how organism looked
- how long ago they existed = deeper underground = older fossil
How is a fossil a record to evolution?
Arrange fossils in chronological order = gradual changes can be observed = evidence for evolution as shows how species changed and developed over time
What evidence shows that simple life forms gradually evolved into more complex ones?
- simple organisms fossils = oldest rocks and complex (vertebrates) = recent rocks so supports that simple life forms gradually evolved into more complex ones
What evidence shows that animals require plants to live?
- plant fossils before animal fossils = consistent with animals need plants to live
What evidence is there that closely related organisms have the evolved from the same ancestor?
- study similarities in anatomy (bone structure) = modern day species link to extinct species
- modern day horse evolved from Eohippus = dog sized animal in rainforest over 60m yrs ago —> multi toed feet for walking across forest floor evolved to single toes for running over grassland
What are there gaps in fossil record?
- not discovered
- many animals = soft bodied so decompose quickly before they fossilise
- many destroyed by volcanic eruptions
How is the Atlantic Tomcod evidence for evolution?
- over past 40 years it’s evolved resistance to PCB (type of industrial waste that is toxic to most living organisms)
What happens to species that don’t adapt to environmental changes?
- die out
- scientists estimate over 99% of all species that ever lived on earth = extinct
How is molecular comparison evidence for evolution?
- compare DNA and proteins of different species
- look at order of nuclei acid bases or amino acid order in a protein
- closely related species have most similar DNA and proteins
- distant related have fewer similarities
What theory did Darwin come up with?
The Theory Evolution by Natural Selection
How did Darwin come up with that theory?
- spent 5 years on a voyage while studying plants and animals
- noticed variation within members of the same species and those with characteristics most suited to the environment more likely to survive (e.g. finches’s beak shape is linked to food type)
- also noticed characteristics were passed on to offspring
- wrote theory of evolution to explain observations
How did Wallace contribute to the theory of evolution?
- Alfred = scientist working at the same time as Darwin
- Wallace’s observations = provided evidence
- ALSO came up with theory and worked on it with Darwin
- BUT Darwin’s ‘On the Origin of Species’ = made other scientists pay attention to Darwin so he’s more remembered than Wallace
Give an example Wallace’s observations:
- warning colours used by some species (butterfly) to deter predators from eating them (advantageous adaption that evolved from natural selection)
How have ideas about evolution influenced modern day biology?
- we understand that all life changes through the process of evolution and we all descend from a common ancestor
How has Darwin’s theory of evolution influenced classification, antibiotic resistance and conservation?
- classification = based on evolutionary relationships
- antibiotic resistance = understand importance of finishing a course of antibiotics to prevent it spreading and need to constantly produce them to stop constantly evolving bacteria
- conservation - understand importance of genetic variation and how it helps populations adapt to changing environments (led to conservation projects)
What did everyone think before Darwin’s theory and when did Darwin publish On the origin of species?
- many people believed all species on Earth were created by God
- 1859
How may plants become extinct?
- changes in environment = we need to evolve to adapt and some become extinct if they don’t evolve quickly enough
- seedbanks store & protect biodiversity (buried in ice to preserve)
What are the uses of seedbanks?
- store lots of seeds (this genetic material) from different species of plants (conserve biodiversity by storing wide variety of plants
- if plants extinct = stored seeds can grow new plants
- help conserve genetic variation = for some species see range of seeds from plants with diff characteristics (diff alleles)
Give an example of when seedbanks conserve genetic variation:
- modern agriculture = little genetic variation in crop species grown = so could easily be wiped out by a particular pest
- traditional versions of crop species may have alleles from pest resistant = if stored = their seeds can produce crops that cope with pests
What is classification?
- process of sorting living organisms into groups with similar features by looking at their similarities and differences
Why do scientists classify organisms?
- identify species
- predict characteristics
- find or show evolutionary links
What is artificial classification?
- uses observable features
- early classification only used observant features (lay eggs, fly)
- artificial classification system
- doesn’t consider evolutionary relationships
When is artificial classification used?
- used to make keys so scientists can identify and group organisms but not the best way
What is natural classification?
- system using evolutionary relationships
- use information about common ancestors and common structural features (bat and human hands are grouped together)
Which classification uses kingdoms to divide organisms and what are the 5 kingdoms?
- natural classification
- plant,animal,fungi, protoctista (amoeba and algae), prokaryotes (organisms with no nucleus)
What are the seven taxonomic groups arranged into their hierarchy?
The kingdom is further divided into
- phylum
- class
- order
- family
- genus
- species
How do you classify something as being in the same species and how many organisms does a species have?
- group that contains only one type of organism
- species is defined as a group of similar organisms that are able to reproduce to give fertile offspring
What is Phylogeny?
- the study of evolutionary links through the study of DNA
- looks at how similar the DNA is and puts it into family trees
How are new evolutionary relation apps being discovered through molecular phylogenetics?
- DNA sequencing = see how closely related organisms are
- compares the sequence of DNA bases for different species = the more similar the DNA sequence between species = the more closely related they are (base sequence for humans and chimpanzee = 94% same)
Describe how Deflex helps people sleep:
- Deflex = depressant.
- works on the synapse
- reduces the amount of neurotransmitters received and sent
- binds with the receptors in the synapse instead of neurotransmitters, so thus it can no longer bind
- also binds and breaks down released neurotransmitters
