4.2: Practical: Investigate the Population Size of an Organism in Two Different Areas using Quadrats

QUADRATS: Rectangular frames of known dimensions that can be used to establish population densities by counting and identifying organisms within frame

MEASURING POPULATION OF ORGANISM:

ESTIMATING POPULATION SIZE OF ORGANISM

Diagram showing How Quadrats are Utilised in the Field

METHOD: Place quadrat randomly within sampling area Count the number of members of the same specieswithin the quadrat Repeat this numerous times within sampling area using the same size quadrat Repeat the process in another area to compare results

CALCULATION: Equation to Calculate the Approximate Population Size of an Organism:

4.1: Understand the Terms Population, Community, Habitat and Ecosystem

DEFINITIONS:

TERM	DEFINITION
POPULATION	All members of single species living in the same area at the same time
COMMUNITY	Groups of populations living and interacting with each other in an area
HABITAT	Environment in which species normally live in
ECOSYSTEM	Community and abiotic environment

4.5: Understand How Abiotic and Biotic Factors Affect the Population Size and Distribution of Organisms

ABIOTIC FACTORS: Non-living environmental factors that can affect organism in ecosystem

• Abiotic Factors can affect a range of Species as each organism is adapted to certain environments

EXAMPLES:

EXAMPLES
Light Intensity	Soil pH	Carbon Dioxide Levels
Soil Moisture Level	Availability of Minerals and Nutrients	Availability of Water
Temperature	Oxygen Levels

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BIOTIC FACTORS: Interactions between living organisms

• Biotic Factors will affect all Species as they have the vulnerability of being food to Predators or being a host to diseases that can affect Population of Species

EXAMPLES:

EXAMPLES
Grazing	Competition for Food	Fungi
Diseases	Competition for Shelter
Predation	Bacteria

4.4B: Practical: Investigate the Distribution of Organisms in their Habitats and Measure Biodiversity Using Quadrats

QUADRANTS: Square Made of Wires that is Divided into Smaller Areas in which Organisms underneath are Identified and Counted

QUADRATS: Rectangular frames of known dimensions that can be used to establish population densities by counting and identifying organisms within frame

MEASURING DISTRIBUTION AND BIODIVERSITY OF ORGANISM:

MEASURING DISTRIBUTION AND BIODIVERSITY OF ORGANISM

Diagram showing How Quadrats are Utilised in the Field

METHOD: Place quadrat randomly within sampling area Count the number of members of the same specieswithin the quadrat Repeat this numerous times within sampling area using the same size quadrat Repeat the process in another area to compare results Additionally, results can be shown on a map of sampled area, displaying which areas are densely populated by certain species and vice versa

INCREASING RELIABILITY OF RESULTS: Randomly place Quadrat Use Quadrat of same size with each repeat Take more samples to collect larger data size

4.3B: Understand the Term Biodiversity

BIODIVERSITY: Measure of the variety of different species living in a habitat (the greater number of different species in a habitat, the greater the biodiversity)

Example:

                    

Picture showing a Forest exhibiting biodiversity as it is home to numerous species of organisms

4.7: Understand the Concepts of Food Chains, Food Webs, Pyramids of Number, Pyramids of Biomass and Pyramids of Energy Transfer

FOOD CHAINS: Shows the feeding relationships between living organisms

FOOD CHAINS

Diagram showing an Example of a Food Chain

EXPLANATION: The Flower is the Producer as it produces their own organic nutrients (Glucose) via Photosynthesis As the Flowers (Producer) will be eaten by Snails, these are the Primary Consumers As the Snails (Primary Consumer) will be eaten by Frogs, these are Secondary Consumers As the Frogs (Secondary Consumer) will be eaten by Foxes, these are Tertiary Consumers at the top of the food chain

FOOD WEBS: Shows how food chains are linked together into more complex feeding relationships

FOOD WEBS

Diagram showing an Example of a Food Web

EXPLANATION:     Food web shows the numerous food chains joined together: Leaf litter → Earthworm → Shrew → Owl Oak tree → Squirrel → Fox Oak tree → Caterpillar → Shrew → Owl     Food Webs show the Interdependence between organisms - change in population of one organism will affect the population of another organism If population of Earthworms decrease, population of Wood mouse may decrease as well as they will have less Earthworms to feed on, leading to starvation and death If population of Shrews increase, population of Owl may increase as well as they will have more Shrews to feed on, increasing chances of survival

PYRAMIDS OF NUMBERS: Shows the population of each organism at each trophic level in a food chain

PYRAMIDS OF NUMBERS

Diagram showing an Example of Pyramid of Numbers

EXPLANATION: In the diagram, the bars represent the population of the organism at each trophic level - the wider the bar, the larger the population As energy is lost to the surroundings from one trophic level to the next, there are usually fewer organisms with each trophic level due to decreasing chances of survival However, some diagrams may not resemble a pyramid as one large producer can feed many small consumers (e.g one Oaktree can feed many Insects)

PYRAMIDS OF BIOMASS: Shows the biomass (amount of living material) of organisms in each trophic level

PYRAMIDS OF BIOMASS

Diagram showing an Example of Pyramid of Biomass

EXPLANATION: In the diagram, the bars represent the biomass of a population of organisms (calculated by multiplying individual biomass by population) Pyramids of biomass will commonly be upright in shape, as the amount of food available (biomass) decreases with each trophic level as energy may be lost via respiration, incomplete digestion, or excretion/egestion

PYRAMIDS OF ENERGY TRANSFER: Shows the transfer of energy with each trophic level

PYRAMIDS OF ENERGY TRANSFER

Diagram showing an Example of Pyramid of Energy Transfer

EXPLANATION: In the diagram, the bar shows the amount of energy available for the next trophic level As energy is lost via respiration, incomplete digestion, or egestion/excretion, only 10% of energy is passed on from one trophic level to the next As a result, this limits the trophic level in a food chain

4.6: Understand the Names Given to Different Trophic Levels, Including Producers, Primary, Secondary and Tertiary Consumers and Decomposers

TROPHIC LEVELS: Position an organism occupies within feeding sequence

DEFINITION:

TERM	DEFINITION
PRODUCERS	Organisms that produce their own organic Nutrients (e.g Plants produce Glucose via Photosynthesis)
PRIMARY CONSUMERS	Herbivores that feed on Plants (Producers)
SECONDARY CONSUMERS	Predators that feed on primary consumers
TERTIARY CONSUMERS	Predators that feed on secondary consumers
DECOMPOSERS	Organisms that release digestive enzymes on dead organisms or non-living organic matter for energy