The document provides information about Edexcel Geography Unit 3: Contested Planet. It discusses the six topics covered in the unit, including how they are linked and the suggested order to teach them. It also provides details about the exam structure, including the format and content of sections A and B. Additionally, it defines key terms related to biodiversity such as ecosystems, biomes, genetic diversity, species diversity, and ecosystem diversity. Finally, it discusses the importance of biodiversity and highlights biodiversity hotspots as areas of very high biodiversity values.
2. The 6 topics of Contested Planet
• The 6 topics in Contested Planet combine into a linked sequence.
• This firstly explores resources, then the differences between rich
and poor.
• Finally a range of solutions to global problems and inequalities are
examined in ‘Technological Fix’. This last topic is summative and
would benefit from being taught last.
3. Exam Unit 3
• Summer 2015
• Two and a half hours.
• Section A:
– Five topics from the six studied. Answer two
questions, each has a section a and b.
• Section B:
– Pre release booklet, 1 question, with three
parts, based on one of the six topics. Answer
all three parts
7. What is an ecosystem?
What is a biome?
An ecosystem is a biological environment consisting of all the organisms
living in a particular area, as well as all the nonliving, physical components
of the environment with which the organisms interact, such as air, soil,
water, and sunlight. It can be as small as a hedge or as large as a
rainforest.
Biomes are climatically and geographically defined similar climatic
conditions communities of plants, animals, and soil organisms over
normally a large area. E.g. Desert.
9. Defining biodiversity
• Biodiversity can be defined in a number
of ways. One of the most common ideas
is that it has three dimensions
• Species diversity is the most commonly
used definition.
Bio…?
•Biodiversity – the variety of genes,
species and ecosystems in an area.
•Biosphere – the thin veneer of living
material on the planet’s surface
•Biome – a global scale ecosystem
e.g. tropical forest
•Biomass - the total weight of living
matter per unit area (dry)
10. What is Biodiversity?
“The variety among living organisms from all
sources including, amongst other,
terrestrial, marine and other aquatic
ecosystems and the ecological complexes
of which they are part; this includes
diversity within species, between species
and of ecosystems.”
The Convention on Biological Diversity
11. Biodiversity Key Facts
• Since the beginning of the century about three-quarters of
the world's crop plant varieties have been lost, and around
50,000 varieties disappear every year.
• The world's population obtains about 90% of its calories
from 20 crop species.
• Tropical forests and woodlands contain at least 50% of all
known plant and animal species.
• Some 40% of the world's market economy is based on
biological products and processes.
• At least 7,000 medical compounds in Western pharmacies
from aspirin to birth control pills are drawn from plants,
mostly from less economically developed countries.
12. Why is Biodiversity Important?
Why biodiversity is
important?
Biodiversity supports
complex interactions
between plants,
animals and people
Biodiversity provides
essential goods and
services, e.g. food,
medicines, raw
materials
Biodiversity and natural
processes are environmental
regulators, e.g. flood control,
soil erosion, clean air etc.
Biodiversity has
aesthetic and spiritual
value – quality of live /
health is closely linked
to the environment
Biodiversity is
valuable for
recreation, e.g. in the
countryside and
urban natures areas
Genetic biodiversity
can control a agro-
ecosystem resistance
to pests / diseases
13. What is biodiversity? (p66 in text book)
Biodiversity
Species
diversity
Ecosystem
diversity
Genetic
diversity
Endemism
(Uniqueness)
Disparity
(Different
species)
Species Richness
(how many species)
Abundance of
species
Total no. of
species
14. A. What is genetic diversity?
Range of genes found within a species. The diversity will
often determine the degree of resistance to pests and
diseases.
In Agribusiness, breeding new varieties of cereals has
led to genetic erosion and genetic pollution. This can
weaken the plant’s resistance.
What impact could
this have in the
future on food
security?
15. B. What is species diversity?
This is the number of different species in a given area.
The ideas of ‘species richness’ and resilience to change.
Most common ‘definition’ of biodiversity.
Diversity is needed to enable the ecosystem to carry out
its functions such as carbon cycling.
What will removal of
species from trophic
levels have on energy
flows and nutrient cycles?
16. C. What is ecosystem diversity?
Range of ecosystem found within an area. The diversity will
often determine the degree of resistance to pests and
diseases. It is partly controlled by physical conditions, e.g.
climate. This includes both biotic (plants and animals) and
abiotic parts (soils, geology and climate).
ParaketsHumans can alter and eliminate ecosystems (e.g. …………….)
and this is an obvious threat to ecosystem diversity.
What local ecosystems are
under threat here from
humans?
17. Advantages Disadvantages
Genetic Diversity
Genetic variation
within species
Helps explain how
isolated groups (e.g.
Birds) have adapted to
new environments.
DNA has to be analysed
so needs high level
biological skills.
Species Diversity
Number of species in
given area
Good basic definition. Size of area can create
problems, larger area
means more species.
Need to compare like
for like.
Ecosystems diversity
Varity of ecosystems
within an area
A more complex measure
of interaction of species
with environment.
Has a wider focus
Where do you place the
boundaries?
Needs a constant set of
criteria to demarcate the
area.
What are the different advantages and disadvantages of using these three
different categories to help define Biodiversity?
Biodiversity is the sum of all three definitions. Whilst species richness is easy to measure,
biodiversity also clearly includes reactions between species and their environments.
18. Biodiversity hotspots – areas of
very high biodiversity values.
Combined area covers only 2.3% of the Earth's land
surface. Each hotspot has already lost at least 70% of
its natural vegetation. Over 50% of the world’s plant
species and 42% of all terrestrial vertebrate species are
endemic to the 34 biodiversity hotspots.
19. Homework
1. Make notes under title of Processes and
factors influencing biodiversity using the
handout (p67-68)
2. Highlight the other handout on What
factors influence Biodiversity? (p58-60)
You will also get a 10 mark quiz on this at
the start of next lesson!