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]
