Evolution Flashcards
What is evolution?
The gradual change in the inherited characteristics of a population over time
How does evolution occur?
Through the process of natural selection, which may result in the formation of new species
What was Darwin’s work?
Proposed theory of evolution by natural selection after gathering evidence from travelling the world, experimentation and discussion.
States that all species evolved from a common ancestor that developed > 3 billion years ago
Why were Darwin’s ideas considered controversial?
1859 Darwin published his theory in On the Origin of species
Challenged the idea that God made all Earth’s animals and plants
Insufficient evidence at the time
Mechanisms of inheritance and variation weren’t known at the time
Other theories e.g Lamarck suggested that changes that occur in an organism over its lifetime are passed on to offspring
What evidence is there for evolution?
Fossil records
Evolution of antibiotic resistance in bacteria
Shown that characteristics are passed on to offspring in genes
What is natural selection?
Organism show a wide range of variation
Individuals with characteristics that are more suited to the environment are more likely to survive and breed successfully
These characteristics are then passed on to
What is speciation?
Alfred Russel Wallace independently proposed evolution by natural selection
He published joint writings with Darwin
Gradual formation of a new species as a result of evolution. Two populations of one species are isolated, natural selection occurs. Populations have an increasing number of genetic mutations as they adapt to different environments
Eventually the two populations are so genetically different that they cannot breed to produce fertile offspring
What is extinction?
Extinction is where thee are no remaining individuals of a species still alive
What factors contribute to extinction?
New predators
New diseases
Increased competition
Catastrophic events
Changes to the environment
How are fossils formed?
The reptile dies and falls to the ground
The flesh decays leaving the skeleton to be covered in sand or soil and clay before it is damaged
Over millions of years, the skeleton becomes mineralised and turns to rock
Rocks shift and the fossil emerges as the rock moves and erosion takes place
What are fossils?
Remains of organisms from millions of years ago, found in rocks
What are fossils formed from?
Parts of an organism that do not decay because one or more of the conditions needed for decay are absent
Hard parts of an organism when replaced by minerals
Preservations of the traces of organisms
Benefits of fossil records
Can tell scientists how individual species have changed over time
Allow us to understand how life developed over Earth’s history
Fossils can be used to track movement of species
Problems with fossil record
Early organisms were often soft bodied and decayed
Gaps in fossil record as some fossils destroyed by geological activity
How are organisms named?
Binomial system of genus and species
Who developed the classification system?
Carl Linnaeus
What is classification based on?
Based on structure and characteristics
Why were new models of classification proposed?
Understanding of biochemical processes developed and improvements in microscopes led to discoveries of internal structures
Who developed the three domain system?
Carl Woese
What are the three domains?
Archaea (extremophiles/ primitive bacteria)
Bacteria (true bacteria)
Eukaryota (protists, fungi, plants, animals)
What is the order of classification?
Kingdom
Phylum
Class
Order
Family
Genus
Species
What are evolutionary trees?
Current classification data for living organisms to demonstrate how organisms are related to
What is resistant bacteria?
Bacteria evolve rapidly because they reproduce really quickly
Strains of bacteria gain antibiotic resistance e.g MRSA
Theory of evolution by natural selection
How do we reduce the risk of antibiotic strains?
Doctors should only prescribe antibiotics for serious bacterial infections
Complete course of antibiotics so all bacteria are killed
Restrict use of antibiotics in agriculture and farming
Who carried out breeding experiments in the nineteenth century?
Gregor Mendel
What plants did Gregor Mendel use?
Pea plants with either green peas or yellow peas
What did Mendel discover?
Each characteristic is determined by units passed on to offspring
Genes can be dominant or recessive
Why was the significance of Mendel’s work not discovered until after his death?
Most scientists believed in blended inheritance
He published his work in an obscure journal
He was a monk, not a scientist
What is the gene theory?
Late C19 - behaviour of chromosomes during cell division observed
Early C20 - genes and chromosomes were observed to behave similarly, leading to discovery of genes located on chromosomes
Mid C20 - structure of DNA and gene function determined
What is a species?
A group of organisms with similar characteristics that can breed together to make fertile offspring
How do we write the Latin name?
Genus species
Why is it important to have a universal naming system?
Otherwise the same organism could have different names, making it hard to share discoveries
