B15 - Genetics And Evolution Flashcards
Evidence of evolution
Fossils
What does archaea mean?
• one of the three domains, containing primitive forms of bacteria that can live in many of the extreme environments
Definition of classification
The organisation of living organisms into groups according to their similarities
Domain definition
The highest level of classification. There are three domains - Archaea, bacteria and eukaryota
Evolutionary trees definition
• models used to explain the evolutionary links between groups of organisms
Extinction definition
The permenant loss of all members of a species from an area or from the world
Species definition
The smallest group of clearly identified organisms in Linnaeus’s classification system, often described as a group of organisms that can breed together and produce fertile offspring
What are fossils?
Fossils are the remains of organisms from millions of years ago that can be found in rocks, ice, and other places.
Fossils give us information about organisms that lived millions of years ago.
• It is very difficult for scientists to know exactly how life on Earth began because there is little valid evidence. Early forms of life were soft bodied so left few traces behind and many traces of early life have been destroyed by geological activity.
Three fossil types
Gradual replacement by minerals/sediment
Casts and impressions
Preservation
Gradual replacement by minerals/sediment
• Hard body parts are eventually replaced by minerals as they decay.
This forms a fossilised substance just like the original hard part
Examples: bones, teeth, shells
Casts and impressions
This is when footprints become buried in clay which is a soft material. The material then hardens, leaving the impression
Eg footprints
Preservation
This happens when there is no oxygen or water for microbes to survive. Also, places might be too air-tight or dry for decay to happen.
Peat bogs, glaciers, sap/amber, tar pits
Causes of extinction
• climate change - animals can’t adapt quick enough
• destroying habitat - species have lots their homes
• poached - for food, fur, coats, jewellery
• pollution - species harmed by pesticides, pollutants
• competition - species forced out of habitat
Causes of extinction
• climate change - animals can’t adapt quick enough
• destroying habitat - species have lots their homes
• poached - for food, fur, coats, jewellery
• pollution - species harmed by pesticides, pollutants
• competition - species forced out of habitat
Antibiotic resistance
Bacteria can evolve rapidly because they reproduce at a fast rate.
• Mutations of bacterial pathogens produce new strains.
• Some strains might be resistant to antibiotics and so are not killed.
They survive and reproduce, so the population of the resistant strain increases by natural selection. The resistant strain will then spread because people are not immune to it and there is no effective treatment.
• MRSA is resistant to antibiotics.
• To reduce the rate of development of antibiotic resistant strains, it is important that doctors do not prescribe antibiotics inappropriately, patients use the correct antibiotics prescribed, and patients complete each course of antibiotics.
• The development of new antibiotics is costly and slow and is unlikely to keep up with the emergence of new resistant strains.
Reasons/causes of antibiotic resistance
• overuse of antibiotics - increases risk of mutation
• failing to complete full course
• use of antibiotics in farming
Who was Carl Linnaeus?
• developed system of classification by looking at characteristics and structure
The 5 kingdoms
• plant - produces food by photosynthesis, don’t move, have a cellulose cell wall
• prokaryotes - single cell with no nucleus
• protists - single cells, some chloroplasts, no cell wall
• animal - consume food, move and have a nervous system
• fungus - do not move or photosynthesise, have chitin cell wall and grow by producing spores
Taxonomy
Classification of species allowed the subdivision of living organisms into smaller and more specialised groups
What are binomial names?
• a system of naming plants and animals giving a name consisting of the genus (with a capital letter) then the species
Homosapien
• wise man
• the species must be in italics or underlined (sapien)
Elements of classification
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
How did new ways of classifying come about?
Traditionally, living things have been classified into groups depending on their structures and characteristics in a system described by Carl Linnaeus.
• Linnaeus classified organisms into kingdom, phylum, class, order, family, genus, and species.
• Organisms are named by the binomial system of genus and species.
• As evidence of the internal structures of organisms became more developed due to improvements in microscopes, and the understanding of biochemical processes progressed, new models of classification were proposed.
What do evolutionary trees show ?
• evolutionary relationships between different species or groups
• show common ancestors, eg apes and humans
• when a line splits into two - splitting into a different species
Who was Carl Woese?
• 1990 - created the three domain system
• evidence gathered from new technologies
• bacteria, archaea, eukaryota
What is bacteria?
True bacteria
Have rigid cell walls
What are eukaryota?
Any species with a nucleus
Why have evolutionary trees changed?
Better microscopes/understanding of DNA and RNA
Darwin’s theory of evolution
• there is natural variation (different alleles) between organisms
• organisms compete for limited resources, such as food
• those better adapted to their environment will survive - this is survival of the fittest
• alleles for ‘successful’ adaptations are then inherited by offspring
Lamark
• had the theory that characteristics were aquired
• eg, a giraffe neck stretches
Why do we need classification?
• to organise and study organisms effectively
• to understand evolutionary relationships
• to analyse biodiversity
• to predict characteristics
