4.) Topic 4 b: Evolution Flashcards
What is evolution and how does is occur?
Evolution is a gradual change in the inherited traits within a population over time
It occurs due to natural selection
Outline the theory of natural selection (6)
- Genetic variation exists due to spontaneous mutations
- Competition between organisms
- A mutation may give an organism a selective advantage
- Organism is better adapted to the environment and survives
- Organism reproduces, passing on its beneficial alleles
- Frequency of advantageous allele increase
Why does competition between organism in a habitat exist? Give examples
The resources within a habitat required for survival are limited
E.g. animals for food, shelter and mates
Why does competition between plants in a habitat exist? Give examples
Competition between plants for light, water and minerals
Describe the role of Darwin in the development of the theory of evolution by natural selection [4]
Studied a variety of organism whilst travelling on the HMS beagle
Noted that traits can passed from parents to offspring
Proposed the idea of ‘survival of the fittest’
Established the theory of natural selection and published his ideas in ‘On the Origin of Species’
Describe the role of Wallace in the development of the theory of evolution by natural selection
Proposed a theory of natural selection that was similar to Darwin’s although the mechanisms were different
Gathered greater evidence (e.g. studying warning colouration in butterflies) to support the theory
How can the effect of camouflage on predator-prey populations be modelled?
- Take a piece of blue paper
- Disperse an equal number of blue straws and white straws across the paper (straws represent population)
- Set a stopwatch for 30s and instruct a volunteer to collect as many straws as possible (volunteer represents predator)
- Record the number of blue straws and white straws remaining
- Repeat 3 times
Describe the limitations of this model
Model: straws do not move, extreme difference in straw colours, paper is one colour, potential bias by volunteer, not affected by other factors
Reality: Prey move - speed affects the likelihood of capture, prey more similar in colour, environment is not one colour, no bias and other factors affect survival
What does it mean by extinct?
All members of species have died
Why may some species become extinct (3)
Organisms not adapted to their environment
Organisms have not adapted rapidly enough to the changing environmental conditions
Outcompeted by better adapted species
Give 3 examples of modern day evolution
Antibiotic-resistant bacteria
Pesticide resistance
Warfarin-resistant rats
Describe how antibiotic resistance in bacteria illustrates the process of evolution
- Genetic variation exists due to spontaneous mutations
- A mutation may give a bacterium antibiotic-resistance
- If an antibiotic is administered, the bacterium is better adapted and survives, whilst the other bacteria are killed
- Bacterium reduces, passing on its resistant variant
- Frequency of antibiotic - resistant allele increases
Why is the development of antibiotic resistance in bacteria a good study for evolution
Bacteria reproduce very rapidly, allowing the first-hand observation of evolution
Why are bacteria becoming increasingly resistant to antibiotics?
Due to overprescription and antibiotic misuse e.g. not completing the entire course
How can we reduce the spread of antibiotic-resistant bacteria? [4]
. Prescribe antibiotics only when necessary
. Ensures patients complete their antibiotic courses
. Reduce the use of antibiotics in farming
. Improve hygiene in hospitals
