Investigating Selection (AQA A-Level Biology): Flashcards
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Directional selection
Directional selection
Selection favouring one extreme; shifts population to that end
Stabilising selection
Stabilising selection
Selection favouring average characteristics; reduces extremes
Example of directional selection in bacteria
Example of directional selection in bacteria
Antibiotic resistance
Example of stabilising selection in humans
Example of stabilising selection in humans
Birth weight
Inhibition zone
Inhibition zone
Clear patch around effective antibiotic on agar plate
Purpose of aseptic techniques
Purpose of aseptic techniques
Prevent contamination by unwanted microorganisms
Negative control in antibiotic test
Negative control in antibiotic test
Disc soaked in sterile water only
Incubation temperature & time for bacterial plates
Incubation temperature & time for bacterial plates
25°C for 48 hours
Bunsen burner role in aseptic work
Bunsen burner role in aseptic work
Creates sterile air currents drawing contaminants away
Effect of natural selection on populations
Effect of natural selection on populations
Modifies allele frequency over time