B14- evolution 🦕 Flashcards
What are fossils ?
Hint: found in
- fossils are the remains of organisms from millions of years ago, which are found in rocks
Name the three ways fossils can form
Hint: absent
- fossils can form from parts of organisms that have not decayed, because one or more of the conditions needed for decay are absent
- fossils may form, when parts of organisms are [slowly] replaced by minerals as they decay
- and, fossils may form as preserved traces of organisms such as: footprints, burrows and rootlet traces [preserved spaces where roots where]
Why might decay be absent ?
Hint: water
- the temperature may be too cold
- there may not be enough oxygen
- and, there may not be enough water
Why can’t scientists be certain about how life began on Earth ?
- many early forms of life were soft-bodied organisms [didn’t have a shell or skeleton], which means they left few traces [few fossils] behind
- and most of the few traces that did form as fossils, have mainly been destroyed by geological activity, as there are changes to rocks in the Earth’s crust
- [so as there are very few fossils of the early forms of life, scientists cannot be certain about how life on Earth began]
What does it mean for a species to be ‘extinct’ ?
Hint: remaining
- a species is extinct, when there are no remaining individuals of that species still alive
Name the three factors that may contribute to the extinction of a species
- species can become extinct due to a catastrophic event [such as an asteroid colliding with the Earth, which eventually lead to the extinction of the dinosaurs]
- a species can become extinct if the environment changes [e.g- changes to weather patterns]
- and, a species can become extinct due to a new disease or a new predator, which kills all of the individuals of a species
- and a species can also become extinct, if a new more successful species evolves and competes with it [due to scare food or scare water]
Why do bacteria evolve rapidly ?
- bacteria evolve rapidly because, they reproduce at a fast rate
What are antibiotics used in ?
- antibiotics are widely used in medicine- to treat bacterial diseases
- antibiotics are also used in farming
Why are antibiotics used in farming ? 🐖
- antibiotics are used in farming, to prevent animals from developing bacterial diseases
How does antibiotic resistance happen ?
- a colony of bacteria have mutations of bacterial pathogens, which produce new strains
- some of these strains are resistant to antibiotics, so these strains survive and are not killed.
- these strains of bacteria now reproduce, so the population of the resistant strain rises.
- the resistant strain then spreads because, people are not immune to it and there is no effective treatment
What is the first step of antibiotic resistance ?
- a colony of bacteria have mutations of bacterial pathogens, which produce new strains
In antibiotic resistance, what happens to the new strains from mutations ?
- some of these strains are resistant to antibiotics, so these strains survive and are not killed.
What happens to the resistant strain of bacteria, that are not killed ?
- these strains of bacteria now reproduce [without any competition from other bacteria] so the population of the resistant strain rises.
What happens after the population of the resistant strain of bacteria rises ?
- the resistant strain then spreads because, people are not immune to it and there is no effective treatment
How can the rate of development of antibiotic resistant strains of bacteria, being reduced ?
- doctors should not prescribe antibiotics inappropriately [e.g- to treat viral infections, as antibiotics only kill bacteria]
- patients should complete their course of antibiotics, so all bacteria are killed and none survive to mutate and form resistant strains
- and, the agricultural use of antibiotics should be restricted [to prevent the spread of antibiotic resistance from animal to human pathogens]
Why can’t researchers keep up with the emergence of new antibiotic resistant strains ?
- the development of new antibiotics is costly and slow, which means it is unlikely to keep up with the emergence of new resistant strains
Who classified species into different categories, based on their structure and characteristics ?
- In the 1800s, the biologist Carl Linnaeus classified species into different categories, based on their structure and characteristics
How were living things originally classified ?
- living things were originally classified [by Carl Linnaeus] into: kingdom, phylum, class, order, family, genus and species
- [remember the mnemonic: kids prefer cheese over fried green spinach]
What two kingdoms were all living things originally divided into ?
- Carl Linnaeus divided all living organisms into two kingdoms: plant and animal kingdoms
- and he then divided each kingdom into smaller categories, which is known as his classification system
How are organisms named ?
- organisms are named by the binomial [two names] system of genus and species
- [this means a species first name will be its genus, and its second name will be its species]
Why have new models of classification be proposed ?
- new models of classification have been proposed because:
- internal structures have become developed due to an improvement in microscopes.
- and the understanding of biochemical processes have progressed [as an organisms’ DNA can be analysed]
What is the three domain system ?
- the three domain system, is a new classification system developed by Carl Woese, who compared the biochemistry of different organisms
- Carl Woese, divided organisms into: archaea, bacteria and eukaryota
In the three domain system, what are archaea ?
- archaea, are primitive bacteria typically living in extreme conditions [such as hot springs and salt lakes]
In the three domain system, what are bacteria ?
- the bacteria domain contains ‘true bacteria’, such as E.coli and they can live in the human digestive system
- true bacteria look similar to archaea [primitive bacteria]; there are multiple biochemical differences between them
In the three domain system, what are eukaryota ?
- the eukaryota domain includes protists [e.g- amoeba], fungi, plants and animals.
What are evolutionary trees ?
- evolutionary trees are a method used by scientists, to show how closely related organisms are to each other
How are evolutionary trees made ?
- to make an evolutionary tree, scientists can use their classification data on living organisms [e.g- DNA]
- ; for extinct organisms, scientists have to use fossils, which present a promblem
When making evolutionary trees, why are using fossils a promblem ?
- the fossil records of many species are incomplete because, there are very few fossils of the early forms of life
