Topic 4 - Genetic Diversity And Adaption Flashcards
What is genetic diversity?
The total umber of different alleles in a population.
What is a population?
A group of individuals of the same species living in the same place and capable of breeding with one another.
What is the importance of genetic diversity?
- greater genetic diversity increases the chance of survival if there are environmental changes
- populations with a wider range of alleles have a higher likelihood of including individuals with advantageous traits for survival
What is a niche?
The role or function a species has within its environment including its interaction with other species and its habitat.
Species with overlapping niches compete, and the better-adapted species outcompetes others.
What is natural selection?
The process where individuals with favourable characteristics are more likely to survive in their environment and reproduce and pass on advantageous alleles to the next generation.
What is evolution?
The change in allele frequencies in a populations gene pool over time.
Why are logarithms used?
When investigating bacterial growth, numbers can increase rapidly, reaching very large values.
Using logarithms simplifies these large values, making them easier to interpret and analyse.
Data is often plotted on a logarithmic scale to visualise patterns and trends clearly.
What is exponential growth?
Population size doubles over a fixed period.
What are the key stages of evolution via natural selection?
- Variation in the phenotypes caused by genetic mutations meiosis and sexual reproduction.
- Environmental change introduces selection pressures such as food availability predators or climate.
- Selective advantage, individuals possessing advantageous alleles provide a selective advantage and are more likely to survive and reproduce.
- Advantageous alleles are inherited to the next generation increasing their frequency.
- This causes a change in the frequency of the alleles over time.
What is directional selection?
Occurs when environmental conditions change, favouring individuals with phenotypes that are suited to the new conditions.
What is the effect of directional selection?
Mean phenotype shifts towards the favoured traits.
What is an example of directional selection?
Antibiotic resistance in bacteria:
- A mutation in some bacteria allows them to produce the enzyme penicillinase, which breaks down penicillin.
- These resistant bacteria survive, reproduce, and pass on the advantageous allele.
- Over generations, the population becomes increasingly resistant to penicillin.
What is stabilising selection?
Occurs when environmental conditions remain stable, favouring individuals with phenotypes closest to the mean.
What is the effect of stabilising selection?
Reduces variation within the population and selects against extremes.
Give an example of stabilising selection
Human birth weights:
Babies with a birth weight around 3–4 kg are more likely to survive.
Those with very low or very high weights are less likely to survive, and these extremes are selected against.
What steps would you take to investigate microbial growth?
- Prepare of the culture medium
- Sterilisation
- Inoculation
- Incubation
- Observation and measurement.
What are the 4 key factors affecting microbial growth?
Temperature: affects enzyme activity
pH: effect enzymes
Nutrient availability: for metabolism and reproduction.
Oxygen availability: aerobic organisms require oxygen for respiration.
What are aseptic techniques?
Flaming inoculation flips and sealing Petrie dishes.
Sterilise surfaces.
Dispose of micro animal waste appropriate to avoid environmental contamination.
