Year 11 Biology Study Notes

Resource Description

Preliminary Biology Study Notes

A Local Ecosystem

Ecology:
Study of living things and their environment

Ecosystem:
Comprises of all abiotic and biotic features and environment of an area

Community:
All the living things within an ecosystem, all the different types and individual organisms

Population:
All the individuals of a particular species living within the same ecosystem

Transect Study:
Cross-section through a study area to analyse the distribution of organisms in that area
Used for stationary organisms such as plants

Quadrat Sampling:
Estimated = Average count x Study area
Population per quadrat Quadrat area

Use of a quadrat to determine the average number of organisms per quadrat
Used to determine abundance / population of an organism
Used for stationary, slow moving organisms

Capture Recapture Sampling:

Estimated = 1st capture x 2nd capture
Population no.marked in 2nd capture
(no. re-captured)

Capture a number of species being studied
Mark or tag the animals
Release the animals back into the environment
Carry out a second capture program
Count how many of the 2nd capture are marked from the 1st capture

Relationships between organisms:
Allelopathy – The chemical restraint of one plant by another
Example – Pine trees drop their needles to the ground and they begin to decompose and release acid into the soil

Parasitism – Relationship in which one organism feeds on another without killing it, or even necessarily harming it significantly.
Example – Mosquitoes benefit, humans are harmed

Mutualism – An interaction which is beneficial to both organisms involved
Example – Beneficial to Oxpecker (a type of bird) and Zebra, Cows and Methanogens

Commensalism – Relationship where one organism benefits while the other is neither harmed nor helped
Example – Cattle Egrets and Cattle, Bird and tree

Competition:
Competition occurs when two different species rely on the exact same sources. These include food or living space. Competition consist of two species and results in a winner and a loser. As one will be more successful than the other, this causes their population to grow, while the loser will decline in numbers and eventually may becomes extinct.

Resource partitioning:
In some cases, two species of organisms who seem likely to be competing with each other.
For example the lion and leopard often live in the same areas and feeding on the large amounts of animals. However, it is shown that their hunting patterns and techniques are different that they naturally tend to prey on different species and categories allowing each other to survive in the same habitat.

Eutrophication:
Occurs when rivers and streams are over fertilised by human sewage or agricultural run off. Results in algae blooming which cover the surface of rivers and streams, preventing the penetration of sunlight, hence effecting photosynthesis rates