332 Understand how resistance to antibiotics can increase in bacterial populations natural selection Natural Selection Darwin put forward the theory of natural selection It can be ID: 540577
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3.30 Describe the process of evolution by means of natural selection. 3.32 Understand how resistance to antibiotics can increase in bacterial populations (natural selection).
Natural SelectionSlide2
Darwin put forward the theory of ‘natural selection’.It can be summarised by the following points:Variation
Over-production
Struggle for existenceSurvival of the fittestAdvantageous characteristics passed on to offspringGradual change
Natural selection Slide3
VariationOrganisms are genetically different, they have different characteristicsSome may be slightly better adapted to their environment than others.
Variation Slide4
Over-ProductionMore offspring are produced than will survive.
Over-productionSlide5
Struggle for ExistenceThere will be competition between organisms for resources e.g. food, water, light, shelter and mates.
Struggle for existenceSlide6
Survival of the FittestOnly those who are best adapted to their environment will survive and reproduce (the strongest).
Survival of the fittestSlide7
ReproduceBeneficial genes and characteristics will be past onto offspring when these organisms reproduceThis is the theory of natural selection - when nature selects which organisms will survive and reproduce. Those that are best-adapted to their environment will pass their genes onto their offspring.
Reproduce Slide8
Some bacteria can become resistant to antibiotics, such as penicillin.Antibiotic resistance