1. Changes in beaks of finches on Daphne Major
5.2 Natural Selection
Understanding:
Natural Selection can only occur if there is variation amongst members of the same species
Mutation, meiosis and sexual reproduction cause variation between individuals in a species
Adaptations are characteristics that make an individual suited to its environment and way of life
Species tend to produce more offspring than the environment can support
Individuals that are better adapted tend to survive and produce more offspring while the less well adapted tend to die or produce fewer offspring
Individuals that reproduce pass on characteristics to their offspring
Natural selection increases the frequency of characteristics that make individuals better adapted and decreases the frequency of other characteristics leading to changes within the species
Applications
Changes in beaks of finches on Daphne Major
Evolution of antibiotic resistance in bacteria
Nature of science:
- Use theories to explain natural phenomena: the theory of evolution by natural selection can explain the development of antibiotic resistance in bacteria

2. Extension: Add on 3 more characteristics you can think of
Prior learning…
Use the words below to create a spectrum of inherited to environmental characteristics
Extension: Add on 3 more characteristics you can think of
INHERITED
ENVIRONMENTAL
Eye colour
Tongue rolling
Hair colour
Accent
Weight
Scars
Tattoos

3. Variation Organisms of the same species with different characteristics
Variation can be affected by the environment or genes
(or both!)
Understanding:
Natural Selection can only occur if there is variation amongst members of the same species

4. Asexual organisms only have genetic mutation to produce variation.
Causes of variation
Genetic mutations in DNA
Meiosis: makes genetically different daughter cells
Sexual reproduction: fusion of male and female gametes (different parents)
Asexual organisms only have genetic mutation to produce variation.
Slow evolution.
Understanding:
Mutation, meiosis and sexual reproduction cause variation between individuals in a species

5. Variation Experiment Collect data. Choose one example of variation.
Draw a bar chart for your data.
Graph paper, rulers and pencils at the front.
Extension: change your height data into data suitable for a bar chart then plot a new graph.
Understanding:
Natural Selection can only occur if there is variation amongst members of the same species

6. To make continuous into discontinuous
Create specific categories. i.e , , etc starting with the lowest in the range and ending in the highest.
Make a tally table:
Draw a bar chart to now show this information as discontinuous.
Height cm
etc
Number of pupils II
IIII

7. Dimples Gender Male or Female Tongue Roll √ if you can or
X if you can’t
Eye Colour
Hair Colour,
Is it natural
or dyed?
Dimples

8. Lobe None Thumbs curved or straight ?
Hair on the middle bit of your fingers (just above knuckles) or none?
Do your little fingers tips bend away from each other?
Lobe
None

9. Showing data

10. …this polar bear was bright pink?
What would happen if…
…this cactus didn’t have spikes?
…this polar bear was bright pink?

12. Adaptations Species adapt to suit their environment
Those that are not well adapted to their surroundings will die.
Those that are well adapted will survive and reproduce
Adaptations are passed on to the next generation
This is survival of the fittest
Understanding:
Adaptations are characteristics that make an individual suited to its environment and way of life

13. Evolution by Natural Selection
Understanding:
Individuals that are better adapted tend to survive and produce more offspring while the less well adapted tend to die or produce fewer offspring
Individuals that reproduce pass on characteristics to their offspring
Natural selection increases the frequency of characteristics that make individuals better adapted and decreases the frequency of other characteristics leading to changes within the species
Evolution by Natural Selection
Charles Darwin

14. They are all adults with different neck lengths!
Once upon a time…
Note: these are NOT baby giraffes
They are all adults with different neck lengths!
Giraffes once had variation in neck lengths

15. Giraffes compete to eat leaves from the trees and bushes

16. Over time the leaves start to thin out on the lower branches…

17. …to the point where the short-necked giraffes can no longer reach

18. The short-necked giraffes can no longer eat so die

19. The long-necked giraffes survive and reproduce to pass on their genes

20. The population of giraffes slowly change to all have long necks.
They have adapted to their environment

21. Different selection pressures
Darwin observed natural selection in the finches of the Galapagos Islands
Different islands
Different selection pressures
Different beaks
Applications
Changes in beaks of finches on Daphne Major

22. Natural Selection: Finches
Which beak will survive and reproduce?
Each person will have a different shape ‘beak’
Each person has to pick up as many bits of food as possible in 1 min with their beak.
All beaks go at the same time in your group: competition (you cannot bat food out of someone's beak!)
Only one piece of food at a time. No scooping.
Record the amount of food each beak picked up at the end of your minute (place into your beakers then count)
Repeat the experiment 3x and find an average for each beak
Sketch a bar chart to show and compare results.
What do your results show? Which bird would most likely survive in this environment? Why?
Applications
Changes in beaks of finches on Daphne Major

23. Darwin's Finches: Natural Selection
Conclusion: Which bird would survive?
Why?
Describe the experiment:
Sketch graph of results:
Extension: Describe the theory of Natural Selection by creating a comic strip (on the back of this page)
Use the following key words:
Natural selection
Variation
Competition
Genes
Survive
Reproduce
Adaptation
Beak 1 2 3
Average

24. Natural Selection Comic Strip
Describe the theory of Natural Selection by creating a comic strip
Use the following key words:
Natural selection
Selection pressure
Variation
Competition
Genes
Generation
Survive
Reproduce
Adaptation
Applications
Changes in beaks of finches on Daphne Major

25. Natural selection - Giraffe

26. Explain how natural selection leads to evolution
Exam Question
Explain how natural selection leads to evolution
6 marks

27. 6 marks variation in a population;
example of an environmental condition/selection pressure;
some are better adapted than others to the environment;
these tend to survive to reproduce themselves;
characteristics are inherited;
so the new generation has these characteristics too;
this leads to changes in the population as a whole;
these changes constitute evolution (by natural selection);

28. Overproduction Huge variations in breeding rates between species
Hornbill: 1 offspring every 3 years
Coconut palm: 60 coconuts per year
Overall trend that organisms produce more offspring than an environment can support
Competition for resources = not all survive and reproduce
Understanding:
Species tend to produce more offspring than the environment can support

29. Antibiotics Chemicals that inhibit the growth of microorganisms
Block processes that occur in prokaryotes (but not eukaryotes)
Do not cause harm to human cells
Cannot treat viral diseases as they lack a metabolism
(viruses only reproduce inside other cells)

30. Antibiotic Resistance

31. A natural population of bacteria has some that are susceptible and some that are more resistant

32. You start taking an antibiotic…

33. And the susceptible (weak) bacteria die first

34. You keep taking the antibiotic, more bacteria die

35. Until eventually only the most resistant bacteria are left

36. You stop taking the antibiotic

37. The more resistant bacteria reproduce and are likely to mutate

38. The more resistant bacteria reproduce and are likely to mutate

39. Now there are lots of more resistant bacteria

40. If I take the antibiotic again, what happens?

41. Nothing! All the bacteria are resistant!

42. Antibiotic Resistance
The danger posed by growing resistance to antibiotics should be ranked along with terrorism on a list of threats nations.
Sally Davies – England Government’s chief medical officer

43. Antibiotic Resistance
When were antibiotics first introduced?
Give examples of antibiotic resistant bacteria
What makes them resistant to antibiotics?
Why is that a problem?
Applications
Evolution of antibiotic resistance in bacteria
Nature of science:
- Use theories to explain natural phenomena: the theory of evolution by natural selection can explain the development of antibiotic resistance in bacteria

44. Exam Question
Explain how natural selection can lead to evolution using antibiotic resistance in bacteria as an example.
9 marks

45. 9 marks members of a population of the same species show variation;
some organisms are more likely to survive due to selective advantage / survival of the fittest;
some organisms have a reproductive advantage;
these variations may be genetically controlled/heritable;
these genes are most likely to be passed on to offspring;
this can change the characteristic of the population;
bacteria can normally be killed with antibiotics;
antibiotics impose a selection pressure;
if a few bacteria have natural resistance to the antibiotic they will survive;
if the resistance is heritable they will pass it on to their offspring;
they will reproduce/evolve to form bacterial colonies resistant to the antibiotic;
example of organism selected by use of antibiotic; (e.g. MRSA bacteria / resistant TB bacteria)