6.3 Genetics & Evolution Flashcards
State two kinds of evidence used to show evolution.
- Fossils
- Antibiotic resistance in bacteria
How are fossils formed?
- Parts of organisms that have not decayed due to conditions needed for decay being absent
- Parts of organisms that have been replaced by minerals as they decayed e.g. bones
- Traces of organisms are preserved, covered in sediment and becoming rock.
Why are there few traces of early life-forms left behind?
They are mostly soft-bodied.
How do fossils act as evidence for evolution?
Scientists can identity the ages of the fossils and use them to show how organisms change over time.
What do branches in evolutionary trees indicate?
Where speciation has occured.
What is extinction?
Where there are no individuals of a species still alive.
State the factors that may lead to extinctions.
- New disease
- Predation
- Competition
- Changes to the environment
- Catastrophic events
What enables bacteria to evolve quickly?
The fast rate of their reproduction.
Outline the process of antibiotic resistance bacteria evolving.
- Mutations occur in bacteria producing genetic variation.
- Certain strains are resistant to antibiotics and are not killed when antibiotic is applied.
- Resistant strains survive and reproduce
- Overtime, the population of a resistant strains increase
Why are resistant strains of bacteria dangerous?
People have no immunity to them and there is no effective treatment.
State an example of a resistant strains of bacteria.
MRSA
What can be done to reduce the rate of development of antibiotic resistant bacteria?
- Refrain from inappropriately prescribing antibiotics e.g. for viral diseases.
- Patients should compete the prescribed course of antibiotics.
- Restrict agricultural uses of antibiotics
Why is is so difficult to keep up with emerging resistance strains
Developing antibiotics have a high cost and take a long time to develop.
