1. Unit 3 Life on Earth
1. Biodiversity and Human Impacts Sampling Techniques Energy Flow Evolution

2. Biodiversity and Human Impacts
Topic 1

3. Biodiversity Key Terms
Definition
Biodiversity
Variety of living organisms on Earth.
Biomes
Regions of our planet as distinguished by their similar climate, flora and fauna e.g. tundra
Habitat
Place an organism lives.
Ecosystem
Habitat + Community
Community
All the living organisms in an area.
Population
A group of living organisms of the one type e.g. dogs
Species
A group of living organisms which are able to interbreed to produce fertile offspring.
Niche
Description of organisms lifestyle/ Role it plays.
Biodiversity match cards for these terms and definitions should be made by students during this first lesson.

4. Biodiversity
Biodiversity is the term used to describe the variety of living things in an ecosystem.
Various factors can affect the biodiversity within an ecosystem, some of which include;
- Abiotic factors
- Biotic factors
- Human influences
Natural hazards
It is important that Biologists keep a close eye on Biodiversity as ecosystems are delicately balanced.

5. Understanding Biomes
Earth is divided into distinct climate zones called BIOMES.
Each biomes contains it’s own animals (fauna), plants (flora) and climate (temperature and rainfall).
Plants and animals within these biomes are specially adapted to survive in their surroundings.
THINK! What animals/plants do you find in the tropical rainforest? Are these the same in the desert or the polar regions on earth? Discuss why!
Research and poster activity for a particular biomes

6. Niches
A NICHE is the term used to describe the lifestyle/ role that an organism plays within its ecosystem.
Factors to consider when describing a niche include: - How that particular organism affects/is affected by other things around it - How it survives/competes
NICHES OFTEN COME UP AS EXAM MCQs
Unit 3 revision question booklet should be used at this point to highlight the MCQ style questions.

7. Human Influences: Air Pollution
Car exhaust fumes contain sulphur dioxide and nitrogen oxides (NOx gases) which combine with rain water to form acid rain.
THINK! Why is acid rain problematic? Discuss.

8. Human Influences: Deforestation
Deforestation is the clearing of vast areas of natural forest without replanting replacement forests.
There are many severe consequences of deforestation: - habitat destruction for many organisms - low-lying downstream areas become flooded - reduced soil fertility of hillsides - higher levels of CO2 contribute to greenhouse effect (climate change)

9. Human Influences: Intensive Agriculture
Farmers create conditions that favour one or two chosen kind of crop plants and thus reduce the natural biodiversity.
Farmers will do this by using:
Herbicides to kill other plants
Pesticides to kill pests that reduce crop value
Fertilisers that favour the chosen crop
Planting GM Crops
Remove hedges for easier harvesting
This lesson could link into research of GM Crops and fertilisers for the assignment task.

10. Effect of Human Influences
Human activities, e.g. pollution, habitat destruction and over hunting, are to blame for the current wave of extinctions.
Currently, extinction is happening x400 than the natural rate
There are several different species threatened with extinction today including;
The killing of lions recently in Africa could be used as a discussion and class debate?

11. Black Rhino

12. Endangered
Californian Condor
California Condor

13. Giant Panda
Endangered

14. Endangered
Snow Leopard

15. Endangered
Blue Whale

16. Tiger
Endangered

17. Mountain Gorilla Endangered
Conservation fact file or ecological footprint calculating activity on the WWF web page.

18. Sampling Techniques
Topic 2

19. Sampling Key Terms Abiotic Factors (Non-living factors)
Biotic Factors (Living factors)
Temperature
Predation
Light Intensity
Disease
Soil Moisture
Grazing
pH of Soil
Food Availability
Match card activity to understand Abiotic and Biotic factors.

20. Abiotic Sampling
Abiotic factors are the NON-LIVING components of any ecosystem.
Experimental sampling of abiotic factors requires good technique to avoid errors whilst using the equipment.
Just as with any experiment it is fundamental that the readings are Repeated for Reliable Results.

21. Abiotic Sampling: Equipment and Errors
Abiotic Factor
Equipment Required
Avoiding Error
Temperature
Thermometer
Leave thermometer to settle for a few minutes before taking a reading.
Light Intensity
Light Intensity Meter
Do not cast a shadow over the solar panel. Stand to the side when taking readings.
pH of Soil
Soil pH Meter
Wipe the probe clean between samples to prevent any cross contamination.
Soil Moisture
Soil Moisture Meter
Wipe the probe clean between samples to prevent cross contamination.
Experiment 1: Abiotic Sampling Take equipment into grounds and sample 3 different areas for comparison. Note your results in your jotters.
ERRORS/ PREVENTIONS OFTEN EXAM QUESTIONS

22. Biotic Sampling: Equipment and Errors
Biotic factors are the LIVING components of any ecosystem. The method used to sample the organisms depends on the type of species being studied.
Experimental sampling of biotic factors requires good technique and set up of equipment to avoid errors.

23. Biotic Sampling: Pitfall Traps
Pitfall traps are a simple method which is used to sample small invertebrates such as insects found in leaf litter/on the floor of woodland etc.
It is essential that the cup is buried level with the soil surface and is well camouflaged with leafs.
THINK! Why is it important to camouflage the top of the cup? What other problems might arise? Are there any types of insects which this method is NOT suitable for sampling? Discuss.
Experiment 2: Biotic Sampling Take equipment into grounds and set up your pitfall traps in various areas. We will return to them tomorrow for the results.

24. Biotic Sampling: Quadrats
For plants and animals which don't move much (i.e. limpets) quadrats are normally used to sample their numbers in an area.
Quadrats must be repeatedly thrown RANDOMLY in the area for reliable results.
Sources of error include the difficulty in identifying the species present and deciding whether or not to include a plant which is partially present in the grid.
Experiment 3: Biotic Sampling Take equipment into grounds* and sample the field with your quadrat. Note any findings in your jotters. *Weather depending

25. Biotic Sampling: Other Methods
Other ways of sampling living organisms that you should be aware of include; - Tree Beating - Tulgren Funnel - Transect - Water Net

26. Energy Flow in Ecosystems
Topic 3

27. Energy Flow Key Terms Term Definition Herbivore
Animal which only eats plants
Omnivore
Animal which eats both plants and other animals
Carnivore
Animal which only eats other animals
Intraspecific Competition
Competition between the SAME species
Interspecific Competition
Competition between DIFFERENT species
Pyramid of Numbers
Pictorial diagram showing the relative numbers of each organism in a food chain.
Pyramid of Biomass
Pictorial diagram showing the relative DRY MASS of each organism in a food chain.
Pyramid of Energy
Pictorial diagram showing the relative energy at each level in the food chain.

28. Energy Flow: Food Chains
Food chains show the DIRECTION of energy flow from producer (green plants) to consumer.
Only 10% of energy is passed on at each level in a food chain.
The other 90% is used in cellular processes, movement, homeostasis (temperature regulation) and excreted as waste.

29. Energy Flow: Food Webs
Food webs are different from food chains as they show intraspecific competition over food sources thus providing a more complete picture of the energy flow.
Experiment 4: Owl Pellet Dissection Tease apart the owl pellet to find out what it has eaten!
Practice questions for food webs unit 3 revision book! Owl pellet dissection.
FOOD WEB EXAM QUs WILL ALWAYS ASK HOW ONE SPECIES AFFECT ANOTHER (BALANCE)

30. Working with Pyramids
Pyramids are used by Biologists to highlight in a pictorial fashion what information they can gather about food chains.
Pyramids of numbers represent how many of each organism there are in one food chain whilst Pyramids of Biomass show the DRY mass of each organism in a food chain.
The shape of these pyramids often form a classic triangle however there are exceptions for number pyramids e.g. when parasites are present or when a large tree is the initial producer.

31. Pyramid Shape Examples
1. Parasites Present
2. Tree as Producer
3. Classic Example

32. Energy Flow: Nitrogen Cycle
It is essential that Nitrogen is recycled between food webs and the ecosystem (Circle of Life).
Nitrogen is needed to make PROTEINS but cannot be absorbed in gaseous form by plants or animals.
Plants must absorb Nitrogen in the form of NITRATES from the soil as shown in the Nitrogen cycle on the next slide.

33. The Nitrogen Cycle
Experiment 5: Root Nodules Prove that nitrifying bacteria can be found in root nodules by growing them on nitrogen free agar plates!
Root Nodule Experiment

34. Convert ammonium into nitrites and then into nitrates
Type of Bacteria
Role in Nitrogen Cycle
Decomposers
Decompose (breakdown) the nitrogen found in dead bodies and waste into ammonium
Nitrifying
Convert ammonium into nitrites and then into nitrates
Denitrifying
Breakdown nitrates releasing nitrogen gas into the air
Nitrogen Fixing
‘Fix’ nitrogen gas from the air into nitrates or protein

35. Over Use of Fertilisers
Farmers often use fertilisers to increase the nutrients in their soil; particularly Nitrogen.
Many problems can arise due to fertiliser over-use; in particular EUTROPHICATION due to nutrients feeding bacteria and causing ALGAL BLOOMS which lead to DECREASED BIODIVERSITY.
4 MARK EXAM QU. MAKE SURE YOU KNOW THE NITROGEN CYCLE AND PROBLEMS!!
Possible pause for research for assignment task on fertilisers?

36. Adaptation, Natural Selection and Evolution
Topic 4

37. Adapt, Nat Selection & Evolution Key Terms
Definition
Mutation
A random change to genetic material (DNA)
Adaptation
An inherited characteristic that makes an organism suited to its environment
Natural Selection
Favourable alleles (genes) are passed on to the next generation.
Evolution
Changes which have occurred over long periods of time to develop new species from one common ancestor.

38. Adaptations
THINK! What are the ADAPTATIONS on the following examples? Are they STRUCTURAL/ BEHAVIOURAL?
Example 1: Cactus
Example 2: Polar Bear

39. Adaptations
Adaptations can arise from a mutation which covets survival.
Mutations can be advantageous, neutral or disadvantageous.
The rate at which mutations appear can be affected by : 1. Exposure to high temperatures 2. Exposure to radiation 3. Exposure to chemicals.
THINK! Can you think of any mutations in humans which are advantageous/neutral or disadvantageous? Discuss.

40. Natural Selection
Natural selection is when alleles (genes) which are favorable to the survival of the species are passed on to the next generation.
The classic example is the peppered moth in Britain:
- White form original (1800s) - Industrial revolution - Soot covered trees - Mutation for colour arose - Black form survived predation - Decrease in pollution means both forms exist today

41. Evolution (Speciation)
There are 4 key stages to the evolution of a species.