International Baccalaureate students wishing to test out of Standard Level biology with Option G may find this useful.

1. Option G
Ecology and Conservation

2. Distribution of Plant Species
• Distribution of species is the range of
places a species inhabits
• Linked directly to abiotic factors
• Abiotic Factors:
– Temperature, water, light, soil pH, salinity and
mineral nutrients

3. Distribution of Animal Species
• Temperature: effects all animals, only some can
survive in extreme temperatures
• Water: animals vary in the amount of water they
require
• Breeding sites: all species breed at some stage in
their life cycle
• Food supply: many need specific foods and can
only live in areas where these foods are
obtainable
• Territory: some animals establish and defend
territories for feeding or breeding (creates an even
distribution)

4. Random Sampling Using Quadrats
• In a random sample, every individual in a
population has an equal chance of being
selected
• Quadrats: square frames used to mark out
sample areas

5. Transects and Distributions
• Transect: line marked out across a site
which indicates where to investigate
plant/animal distributions along
– Useful when there is a gradient in an abiotic
factor

6. The Niche Concept
• Ecological niche: the mode of existence of a
species in an ecosystem
– Habitat: where the species lives in an ecosystem
– Nutrition: how the species obtains its food
– Relationships: interactions with other species in the
ecosystem
• Two species with a similar niche will compete in
the overlapping parts, yet will most likely coexist
• Two species with exactly the same niche will
always compete and one will become superior
• Competitive exclusions principle: only one species
can occupy a niche in an ecosystem

7. Fundamental and Realized Niches
• Fundamental niche: potential mode of
existence, given the adaptations of the
species
• Realized niche: actual mode of existence,
results from its adaptations and
competition from other species
• Differences between the two niches are
due to competition

8. Interactions Between Species
• Herbivory: primary consumer feeding on a plant or other
producer
– relies on producer’s growth
• Predation: consumer feeding on another consumer
– relies on number of prey
• Parasitism: organism that lives on or in a host and obtains
food from it
– Host is always harmed
• Competition: two species using the same resource compete
– When one species uses more of a resource the other species
suffers
• Mutualism: members of different species that live together in a
close relationship
– Both benefit

9. Measuring Biomass
• Biomass: total dry mass of organic matter
in organisms or ecosystems
1. Representative samples are collected
2. Organisms are sorted into trophic levels
3. Organisms are dried in an oven from 60-80
Celcius
4. Mass is measured with an electronic balance
5. Drying and measuring may be repeated

10. Constructing Pyramids of Energy
• The lowest bar of a pyramid of energy is the gross
production (total amount of organic matter
produced by plants)
• Energy flow measured in kilojoules of energy per
square meter per year
• Net production: amount of gross production in an
ecosystem after subtracting the amount used by
plants in respiration
• Upper bars of a pyramid are the energy that flow
through groups of consumers; amount of energy in
the food they eat

11. Difficulties with Trophic Levels
• Many species exist partly in one trophic
level and partly in another
• Examples:
1. Chimpanzees eat fruit and plants, but also
termites and larger animals; both first and
second consumers
2. Oysters consume ultraplanktonic producers,
microplanktonic consumers, and dead
organic matter; first and second consumers
as well as detritivores

12. Ecological Succession
• Ecological Succession: series of changes to an
ecosystem
– Primary succession: starts in an environment where
living organisms have not previously existed
• New island created by volcanic activity
– Secondary succession: areas where an ecosystem is
present, but is replaced by other ecosystems,
because of a change in conditions
• Abandoned farmland developing into a forest
• Common changes: soil erosion is reduced due to
roots of large plants; amount of organic matter in
soil increases as plants/organisms release more
organic matter

13. Biomes and Biosphere
• Biome: a type of ecosystem
– Determined mainly by rainfall and
temperature of the area
• Biosphere: made up of the biomes of the
world together

14. Major Biomes of the World
• Desert: low rainfall, warm/hot days, cold nights, few plants
• Grassland: low rainfall, warm/hot summers, cold
winters, grasses/herbs
• Shrubland: cool wet winters, hot dry summers, fires, drought-
resistant shrubs and evergreen foliage
• Temperature deciduous forest: moderate rainfall, warm
summers, cool winters, trees that shed their leaves, shrubs
and herbs
• Tropical rainforest: High rainfall, hot in all seasons, huge
diversity of plants
• Tundra: low temps, little precipitation (mostly as snow), small
trees, few herbs, mosses and lichens are present

15. Biodiversity
• Abbreviation of the term “biological
diversity” from 1986
• Encompasses the diversity of ecosystems
on Earth, the diversity of species within
them, and genetic diversity of each
species

16. The Simpson Diversity Index
• Overall measure of species richness in an
ecosystem
1. Collect random sample for organisms
2. Identify each of the organisms found
3. Count total number
4. Calculate D (the index)
N = total number of organisms
n = number of individuals per species

17. Reasons to Conserve Rainforest
• Economic reasons: new commodities may be
found (medicine, raw materials), new crops or
farm animals, ecotourism
• Ecological reasons: fix large amounts of carbon
dioxide, damage can cause soil erosion, silting up
of rivers, flooding, change in weather patterns
• Ethical reasons: every species has a right to live,
cultural importance to indigenous humans, deprive
future humans the experience
• Aesthetic reasons: beautiful and enjoyable
species, artists find inspiration here

18. Biomagnification
• Biomagnification: the process by which
chemical substances become more
concentrated at each trophic level
• PCBs are chemicals that were used as
insulators used until 1970s that are now
detectable throughout the world;
Persistent and very toxic

19. Impacts of Alien Species
• Alien species: one that humans have
introduced to an area where it does not
naturally occur
• Causes interspecific competition and
species extinction
• Rats introduced to New Zealand killed off
bird species (Big South Cape Island)

20. Ozone and Ultra-Violet Radiation
• Ultra-violet radiation damage:
– Increases mutation rates by damaging DNA
– Causes cancer (especially skin cancer)
– Severe sunburns and cataracts of the eye
– Reduces photosynthesis rates and so affects
food chains
• Without the Ozone layer there would be a
greater amount of ultra-violet radiation
• CFCs are the main cause of ozone depletion