4.5(a&b) Food Chains and Food Webs

4.5a Food Chains 



Food Chains link together:
Producer ----> Primary Consumer ------> Secondary Consumer -----> Tertiary Consumer

• Only one organism per trophic level
• You cannot show an organism being an omnivore / cannot show organisms feeding at more than 2 trophic levels
• Food Chains show the flow of matter and flow of energy

4.5b Food Webs




The food web allows us to provide a better description of the ecosystem (ecosystems are community of organisms interacting) In this case interacting = feeding

Feeding at different trophic levels:
consequences
- organisms can have multiple predators
- may be feeding on multiple pray
- resulting to the food chains becoming linked.

4.2 Quadrates

Sand-dune Ecosystem - it is made up of a number of populations which form the community and the habitat

The fence line running in the middle splits the sand-dune area into: GRAZED and UN-GRAZED by cattle. Therefore, there are two different areas within an ecosystem.

How to study the populations in the different sides: Count the number of individuals in the population.

Quadrating - when you separate land into squares using metal, wood and string (From 0.25m x 0.25m up to 1m x 1m)

It is used to sample the area and count the number of individuals inside the grid. This will be repeated a number of times = Estimate of the population size

"Quadates are a method of sampling different locations so that populations can be compared in the two different locations"

4.1 Ecosystems

Ecosystem: 

Community of organisms:

It is made up of population of difference species and they are interacting.

Population: Number of individuals of a particular species

Species: Organisms that reproduce to give fertile offspring

Habitat (Abiotic - non biological factors):
1. Daylight / Dark
2. Temperature
3. Rainfall
4. Humidity
5. Slope of the land

All of these factors are non biological factors.


- the common interaction is feeding


"A ecosystem is a community of organisms in a particular habitat. Community is made up of different populations of the different species interacting within that habitat"