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.
