OCR F215 Ecosystems

HideShow resource information
  • Created by: Bethany.
  • Created on: 30-04-16 21:13
Preview of OCR F215 Ecosystems

First 459 words of the document:

F215 Module 3: Ecosystems and Sustainability
5.3.1 Ecosystems
(a) define the term ecosystem
Ecosystem ­ all living organisms and nonliving components in a specific habitat, and the interrelationships
between them.
Habitat the place where an organism lives.
Population all of the organisms of one species , who live in the same place at the same time, and can breed
Community all the organisms of different species, who live in the same place at the same time, and can interact
with each other.
Niche the role that each species plays in an ecosystem.
Autotroph an organism that uses light energy to synthesise its own complex organic molecules.
Heterotroph an organism that consumes complex organic molecules to gain nutrients, obtaining energy.
(b) state that ecosystems are dynamic systems
Ecosystems are dynamic systems because the population rises and falls due to the interactions of living organisms
between each other and with the physical environment. Any small changes in one thing can affect the others. For
example, if a predator's population size goes up, the population size of the prey will go down.
(c) define the term biotic factor and abiotic factor, using named examples
Biotic factors ­ the effects of living organisms, e.g. food supply, predation, disease, competition.
Abiotic factors ­ the effects of nonliving components, e.g. temperature, pH of soil, soil type, light intensity,
oxygen concentrations, carbon dioxide concentrations.
(d) define the term producer, consumer, decomposer and trophic levels
Producer An organism that converts light energy to chemical energy /converts inorganic molecules to
organic molecules autotroph.
Consumer An organism that receives energy by feeding on other organisms heterotroph.
Decomposer An organism that feeds on dead organic material releasing molecules, minerals and energy for
other living organisms.
Trophic Levels The position at which an organism is at in a food chain or web.
(e) describe how energy is transferred through ecosystems
Food chains show how energy is transferred from one organism to another.
Different food chains join together to make a food web , which helps us
understand how energy flows through the whole ecosystem. The arrows in a
food chain show the direction of energy transfer.
(f) discuss the efficiency of energy transfers between trophic levels
Energy is lost at each trophic level and is unavailable to the next
trophic level. Energy is used for respiration which is lost through
heatenergy . The energy is stored in dead organisms and waste
material which can only be accessed by decomposers . Because of this,
there is less living tissue (biomass ) at higher levels of a food chain .

Other pages in this set

Page 2

Preview of page 2

Here's a taster:

F215 Module 3: Ecosystems and Sustainability
There are always less consumers as the pyramid gets higher due to energy loss at each trophic level.
(g) outline how energy transfers between trophic levels can be measured
Pyramids of Biomass Pyramids of Energy Productivity
Each bar within the pyramid is Different organisms may release Productivity is the rate at which
proportional to the dry mass of all different amounts of energy per energy passes through each trophic
organisms at that trophic level. All unit mass.…read more

Page 3

Preview of page 3

Page 4

Preview of page 4

Here's a taster:

F215 Module 3: Ecosystems and Sustainability
Count the number of individuals of each species.
Estimate the percentage cover of each species this is the proportion of the area within the quadrat which it
Use an abundance scale , such as the ACFOR scale, by estimating which one of these best describes the
abundance of each species within the quadrat.
A point quadrat may be used. This is a frame holding a number of long needles or pointers.…read more

Page 5

Preview of page 5

Here's a taster:

F215 Module 3: Ecosystems and Sustainability
Nitrification happens when chemoautotrophic bacteria in the soil absorb ammonium ions .
Ammonium ions (NH4 ) are released by bacteria involved in putrefaction of proteins found in dead or waste
organic matter.
Chemoautotrophic bacteria obtains energy by oxidising ammonium ions (NH 4 ) to nitrites (NO2 )
( Nitrosomonas bacteria), or by oxidising nitrites (NO2 ) to
nitrates (NO3 ) (
Nitrobacter bacteria).
As oxidation requires oxygen, these reactions only happen in wellaerated soils.…read more


No comments have yet been made

Similar Biology resources:

See all Biology resources »See all resources »