1. Human Impact on the environment

2. KA 5 Success Criteria
I can state that increasing human populations require increased food yield
I can explain the impact of using fertilisers can have in freshwater ecosystems
I can describe how pesticides can accumulate in a food chain and its effects.
I can state some examples of indicator species and state how their presence or absence indicate environmental quality/levels of pollution.
I can explain how GM crops may be an alternative to the use of fertilisers and biological control may be an alternative to the use of pesticides.

3. Learning Intentions I can:
state that increasing human populations require increased food yield
explain the impact of using fertilisers can have in freshwater ecosystems

4. Ways of increasing food yield
What does intensive farming mean to you?

5. Chicken battery farm
Discuss the reasons why farmers keep their animals confined in small spaces

6. Pig battery farm

7. Monocultures
Discuss with pupils what they think a monoculture is?

8. Advantages Crop is grown to soil type and climate
Machinery used so labour costs are low and speeds up planting and harvesting
More than one harvest a year.
All have increased crop yield.

9. Agriculture tend to grow monocultures
Monoculture: one plant species grown over a large area. Grown to increase food yield for growing human population. (Add to glossary)
In a meadow consisting of a variety of plant species normal competition will control pests and weeds.
Problems
In a monoculture, you have to control hungry pests and weeds artificially. (PESTICIDES , FUNGICIDES and HERBICIDES)
Over time the same plant grown in the same area will deplete the soil of nutrients, therefore you need fertiliser.

10. Main Disadvantages
Large risk of disease as crops genetically identical. Increased risk of pests and damage to crops due to the close planting.
Large scale use of fertilisers and potential for pollution problems.
Machinery compacts soil so less oxygen available to crops. Decrease crop yield
Hedgerows removed to increase field size but reduces biodiversity.

11. Fancy a swim? – Where has all that algae come from?

12. Algae block out the light and prevent green plants below the surface getting enough light for photosynthesis.
When the algae die they become organic waste (just like sewage) and provide food for micro-organisms (bacteria).
Bacteria feed on the algae and reproduce causing an increase in numbers.
The increased numbers of bacteria use up more oxygen in respiration and reduce the oxygen available to other organisms.
As a result many water organisms die and the number of different species decreases. i.e. biodiversity decreases.

13. Can you explain why all these fish have died?

14. To get an excellent presentation of the process of Eutrophication click here

15. Less availability of oxygen for other organisms!!!
Aquatic plant and algae die
eaten by increasing numbers of bacteria
Large quantities of oxygen used up by bacteria
Algal bloom
decreases
Light level
Fertilisers leach into freshwater
increases
Algal blooms
Do past paper Q10c on page 40
Less availability of oxygen for other organisms!!!
Do specimen paper Q10c on page 40

16. L.I To describe ways of increasing crop yield without fertilisers.
Prior KU
Negative Impact fertilisers have on a fresh water ecosystem.
State the process that occurs when excess fertiliser leaches into freshwater ecosystems
Eutrophication
Now add key word and definition to glossary

17. Reducing the problem caused by fertilisers
Farmers could use natural fertilisers such as manure and compost to stop the risk of algal blooms.
They could also use less fertilisers by using crop rotation.
Use Genetically modified (GM) crops as an alternative. GM seeds may produce plants which can grow in lower concentrations of soil nitrogen or grow plants that require less water.
S.C: I can explain how GM crops may be an
alternative to the use of fertilisers
Click above for clip on benefits of using GM seeds

18. learning intentions
Name a pesticide which will not break down in the environment.
Describe how pesticides can kill other organisms.
Explain advantages of using biological control over pesticides.

19. Types of Pesticides
These are chemicals sprayed onto crops to reduce competition from other organisms.
Herbicide: kill _______________
Fungicide: kill ______________
Insecticide : to kill ____________
Bactericide : kill ______________

20. Research Activity
DDT, a useful pesticide in 1945, was found to have lots of toxic effects on the environment, especially birds.
DDT is not easily broken down by the environment.
Bioaccumulation occurred in the top carnivores of a food chain
Research the consequences of using DDT on birds. (Include your source
from website and state why you
think it is a reliable source.)
Research Optional if time -write notes an appropriate title using information from slide to introduce what DDT is

21. Using Processing skills to explain bioaccumulation

22. Using Processing skills to explain bioaccumulation
Each leaf receives one “dose” of DDT when sprayed.
Each worm eats 3 leaves.
Each robin eats 2 worms.
Each sparrow hawk eats 2 robins.
How many doses of DDT does the sparrow hawk eat?

23. 12
2. If they eat enough DDT, birds lay eggs with very thin shells, which break before they are ready to hatch. How might this effect the sparrow hawk population, and the other members of the food chain?

24. Review of research Was the information you gathered relevant?
Was your source reliable ?
E.g.
Information gathered was from a NAT 5 revision website which is an aid pupils use to improve their chances at performing well in the final exam. The information is at the appropriate level and linked to SQA mandatory knowledge.
Wikipedia is not a reliable source as anyone can access the information and alter it.

25. Summary
Pesticides sprayed onto crops can accumulate in the bodies
of organisms over time. As they are passed along food
chains toxicity increases and can reach lethal levels.

26. Biological control as an alternative to the use of pesticides
The practice or process by which an undesirable organism is controlled by means of another (beneficial) organism.
Ladybirds significantly reduces aphid (greenfly) numbers which would normally feed on the sap of the growing plant causing it to wilt.

27. Indicator species
An indicator species if present or absent indicate environmental quality/levels of pollution.

28. Lichens Lichens are an indicator species which give information
about the levels of sulphur dioxide pollution in the air
Sulphur dioxide is a pollutant produced by the burning of fossil fuels such as coal, oil and gas

29. Level of pollution indicated
Type of Lichen
Level of pollution indicated
Leafy
Crusty
Powdery
None
Draw a table with the following headings to show the different types of
lichens and what level of pollution they indicate.

30. High sulphur dioxide pollution
Indicator lichen type
None

31. Low sulphur dioxide pollution
Indicator lichen type
Crusty

32. No sulphur dioxide pollution
Indicator lichen type
Leafy

33. Moderate sulphur dioxide pollution
Indicator lichen type
Powdery

34. An indicator species if present or absent indicate environmental quality/levels of pollution. (add to glossary)
Several Indicator species can be used identify the levels of pollution in river

35. Sewage Works Direction of Flow Caddis Fly Larva Fresh Water Shrimp
Stonefly Nymph
Mayfly Nymph
Stonefly Nymph
Mayfly Nymph
Sludge Worm
Rat Tailed Maggot
Water Louse
Blood Worm
Direction of Flow
Very low levels of organic material
Very low levels of Bacteria
Very high levels of Oxygen
Very high levels of organic material
Very high levels of Bacteria
Very low levels of Oxygen
High levels of organic material
High levels of Bacteria
Low levels of Oxygen
Low levels of organic material
Low levels of Bacterial
High levels of Oxygen
Very low levels of organic material
Very low levels of Bacteria
Very high levels of Oxygen
Task complete cut out work sheet with this slide

36. Testing river water samples
Methylene blue dye tests for oxygen in water.
The darker the colour, the more oxygen there is. Which of these tubes contains yeast?
Lets test 2 samples A)unpolluted and C)polluted river water for oxygen availability
Sample B) is the control
Practical opportunity

37. Pollution & bacteria levels
Analyse this graph and draw a valid conclusion.

38. Pollution & bacteria levels
As the bacterial level increases the O2 level decreases because the bacteria use it up in respiration.

39. KA 5 Success Criteria
I can state that increasing human populations require increased food yield
I can explain the impact of using fertilisers can have in freshwater ecosystems
I can describe how pesticides can accumulate in a food chain and its effects.
I can state some examples of indicator species and state how their presence or absence indicate environmental quality/levels of pollution.
I can explain how GM crops may be an alternative to the use of fertilisers and biological control may be an alternative to the use of pesticides.

40. N5: Revise key areas for Unit 3 Nab
1. Biodiversity and Ecosystems 2. Energy in Ecosystems 3. Sampling techniques and measurement of abiotic and biotic factors 4. Adaptation, natural selection and evolution of a species. 5. Human impact on the environment