Download Module 4: Genetics

Option G:
Ecology and Conservation
G.1 Community Ecology
What are abiotic factors?
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Temperature
Soil pH
Salinity
Mineral components
Water light
Humidity
Amount of precipitation
Etc.
G.1.1 Outline the factors that affect the distribution of plant
species, including temperature, water, light, soil pH, salinity and
mineral nutrients
Abiotic factor
Explanation
Temperature
Organisms can only survive within a
narrow range from which it is adapted to
Light
Light intensity/wavelength/duration and
quality is important for photosynthesis
Soil pH
Most plants only tolerate a narrow pH
range
Salinity
Most plants can’t tolerate high
fluctuations in salinity
Mineral nutrients
Affects plant fertility, soil structure, and
water retention
Water
Limiting factor in most terrestrial
ecosystems and plants are classified
according to their ability to tolerate water
shortage
G.1.2 Explain the factors that affect the distribution of animal
species, including temperature, water, breeding sites, food supply
and territory
Abiotic/biotic
factor
Explanation
Temperature
Must be within viable range of adapted animal
Water
Must be species-specific quantities
Breeding sites
Maintenance of species
Food supply
Right kind for species
Territory
• Breeding or feeding
• Dissolved oxygen affects aquatic species
• Salinity may affect some species
G.1.3 Describe one method of random sampling based on quadrat
methods, that is used to compare the population size of two plant
or two animal species
The Quadrat Method
• Squares of a certain size are made
• Randomly choose a square
• Organisms within the square are counted
• This number is used to determine the population size
Why is this method better used for plants
rather than animals?
Using the quadrat method, find out how many there are of the
following:
Venus flytraps
Roses
Orchids
Why is this method better used for plants
rather than animals?
G.1.4 Outline the use of a transect to correlate the distribution of
plant or animal species with an abiotic variable
G.1.5 Explain what is meant by the niche concept, including an
organism’s spatial habitat, its feeding activities and its interactions
with other species
Spatial habitat: area inhabited by organism
Feeding activities: affects ecosystem by keeping other
organisms in check
Interactions:
• Competition
• Herbivory
• Predation
• Parasitism
• Mutualism
G.1.6 Outline the following interactions between species, giving
two examples of each: competition, herbivory, predation,
parasitism and mutualism
Jigsaw task: You will randomly be placed in expert groups for
one type of interaction and you will quickly research and find
two examples of it. After you will get back to your home groups
and share your findings with them.
1. Competition
2. Herbivory
3. Predation
4. Parasitism
5. Mutualism
G.1.7 Explain the principle of competitive exclusion
No two species in a community can occupy the same niche
G.1.8 Distinguish between fundamental and realized niches*
Fundamental niche:
• The potential niche of an organism under ideal conditions
with its adaptations
Realised niche:
• The actual niche of an organism which is restricted by the
environment and competition
G.1.9 Define biomass
The total dry organic matter of organisms/ecosystems (g m-2yr-1)
G.1.10 Describe one method for measurement of biomass of
different trophic levels of the ecosystem
• Measure total area of ecosystem (e.g. a forest)
• Divide ecosystem into small areas (e.g. grids or plots marked
with a stake carrying a number)
• Choose one sample plot
• Measure size of each plant species (height and diameter).
Extract all vegetation from plot.
• Dry all samples in circulating drying oven at 90°C
• Use mathematical model to show relationship between
weight and height of each plant species and its biomass
• Sample other plots (size and height only)
• For animals, trap them and weight and measure them. Use
tables to determine their biomass
• Average data for all species per plot
• Multiply the average per plot by the number of plots in
ecosystem