B15-Genetics and evolution Flashcards
What is a fossil?
The remains of a plant or animal from millions of years ago that have been preserved
What are the 3 main ways fossils can form?
1-preserved traces(footprints/burrows/rootlet traces)
2-when parts of the organism doesn’t decay because one or more of the conditions for decay are absent
3-when parts of the organism are replaced by minerals as decay happens
What are the criteria for decay to occur?
Oxygen, bacteria(decomposers), correct temperatures
Why are fossils important?
To look at the anatomy of animals
How animals develop
All cells have a very similar chemistry-enzymes, DNA, ribsosomes etc.
Some organisms can be obseved evolving eg bacteria
Name the person who first discovered inherited characteristics are determined by ‘units’ passed on unchanged
Gregor Mendel
Why were Mendel’s ideas of inheritance not accepted during his time?
As chromosomes weren’t discovered
Who published the double helix structure of DNA?
Watson and Crick
Watson and Crick used whose work to find out the structure of DNA?
Franklin and Wilkins(but without Franklin’s permission)
Name the person who proposed the theory of evolution
Charles Darwin
Name the person who suggested changes that occur in an organism during its lifetime can be inherited
Jean-Baptiste Lamarck
On what mechanism is Darwin’s theory of evolution based on?
Natural selection
What is Darwin’s theory of evolution by natural selection?
All species have evolved from simple life forms
State 3 reasons why Darwin’s ideas were only slowly accepted
1-conflict with the wild belief that God made all living things
2-insufficient evidence
3-no mechanism to explain variation and inheritance
Who worked with Darwin to develop the theory of evolution?
Alfred Russel Wallace
Apart from evolution what are 2 other studies Wallace worked on?
Warning colouration in animals+theory of speciation
What is speciation?
The process by which 2 species evolve from a single original species by natural selection
Give the 6 steps in the process of speciation(how does a new species arise)
1-geographical isolation(eg flood divides an island in 2)
2-different selection pressures/conditions in the new environments
3-genetic variation(bc of mutations) within the groups
4-best adapted individuals to the new conditions survive, reproduce and pass on these favourable alleles
5-no interbreeding over time, groups become more different to each other
6-after a large amount of time, unable to interbreed successfully-they’re now separate species
Describe the 5 steps of fossilisation by mineralisation
1-organism dies and falls to the ground
2-flesh decays, leaving skeleton behind
3-bones are covered in sand/soil
4-bones become mineralised and turns into rock(fossil)
5-rock with fossil emerges due to geological movement(earthquake) and erosion occurs to reveal fossil
Give 4 reasons why the fossil record is incomplete
1-many earliest life forms are soft-bodied
2-most organisms didn’t become fossilised
3-most early fossils were destroyed by geological activity
4-many fossils are not yet found
How is the fossil record helpful?
Shows how much organisms have changed and developed over time and can show the environment and climate then
Define extinction
Permanent loss of all members of a species
State 3 causes of extinction
New predators, new diseases/pathogens, new successful competitors
What causes mass extinction? Suggest 2 examples of this cause
Single catastrophic event that also affects climate over a long period(eg asteroid collision, volcanic eruption)
Suggest a chain of events initiated by an asteroid collision that could lead to the extinction of dinosaurs
Asteroid impact causes huge fires and earthquakes–>volcanic eruptions–>dust/ash cloud covers atmosphere–>less sunlight reaches the Earth surface–>temp drop massively+plants die–>loss of food source led to other animals’ extinction
What is antibiotic resistance?
Bacteria becoming resistant means it cant be killed by a certain antibiotic
What causes antiobiotic resistance?
Random mutations in bacteria/bacteria sharing resistant genes
Describe the steps in which a bacteria strain develops resistance to an antibiotic
1-mutation occurs in an individual bacterium within a population
2-it survives and reproduces rapidly, making more bacteria with its resistant gene
3-overtime all bacteria within the population have that gene
Why can bacteria evolve quicker than other organisms?
Because bacteria can reproduce at a quick rate
What is a genome?
The entire set of genes for an organism
GIve 2 advantages of understanding the human genome
Identifying genes linked with inherited diseases , understanding human migration and evolution
How 2 species of aniamls could have arisen from a common ancestor(speciation 6 marker)
Geographical separation; environmental differences, random mutation/variation, best adaptted in each aea survive breed and pass on allelses and genes, eventually the different populations can no longer succeessful breed with each other to produce fertile offspring
Suggest 3 methods to prevent and slow down the development of antibiotic-resistant strains
1) Do not overuse antibiotics
2)patients finish anitbiotic course every time
3) restrict agricultural use of antibiotics
Why must patients finish their course of antibiotics every time?
To ensure all bacteria are killed by the antibiotic so none can survive to mutate and develop resistance
Suggest 3 ways in which a hospital can reduce the spread of antibiotic-resistant strains
Only use antibiotics if really needed, use strain-specific antibiotics, maintain high hygiene standards(wash hands between patient visits), isolate patients infected with resistant strain, vistors wash hands as they enter and leave
Why is it difficult to develop new antibiotics to combat the appearance of new antibiotic-resistant strains of bacteria?
The development of new antibiotics is expensive and slow(won’t be able to keep up)
What does classification of organisms mean?
Organisation of living things into groups based on thier similarities
Name the person who developed the classification system
Carl Linnaeus
State the 7 hierachical levels of the Linnaean classification system
Kingdom, phylum, class, order, family, genus, species
Every organism has a scientific name using a binomial system-what does binomial mean?
2 names
Which language does the binomial naming system use?
Latin
The binomial name of an organism is made up of 2 words-what does each word represent of that organism?
The 1st word is the genus; 2nd word is the species
What are the 3 rules of writing a binomial scientific name of species?
1st letter of the genus should be in capital; 1st letter of the species should be in lower case letter; both need to be in italics when printed or underlined when hand-written
Why do we use the binomial naming system?
Every organisms’ names would vary in different language, but Latin is considered to be the old common language in which everyone can use/understand
How many domains and kingdoms do scientists now consider in classifications?
3 domains, 6 kingdoms
Based on what knowledge were the 3 domains set?
Different biochemistry of cell and ribosomes, and how cells reproduce differently
What are the 3 domains?
Archaea, bacteria, eukaryota
What are the 6 kingdoms?
Archaebacteria, eubacteria, protista, fungi, plants, animals
How is classification helpful?
Helps us to understand evolutionary and ecological relationships, makes them easier to study, helps us recognise biodiversity and gives scientists a common language in which to talk about it
Name the type of models that are used to show how different organisms are related
Evolutionary trees
What aspects of knowledge would be considered when suggesting evolutionary relationships?
Similarities and differences in physical structures, genetics and biochemistry
