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A Local Ecosystem

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charlie mccabe

on 9 June 2015

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Transcript of A Local Ecosystem

A Local Ecosystem
8.2.1 The distribution, diversity and numbers of
plants and animals found in ecosystems are determined
by biotic and abiotic factors
identify uses of energy by organisms
identify the general equation for aerobic cellular respiration and outline this as a summary of a chain of biochemical reactions
8.2.2 2. Each local aquatic or terrestrial ecosystem is unique
examine trends in population estimates for some plant and animal species within an ecosystem
outline factors that affect numbers in predator and prey populations in the area studied
identify the factors determining the distribution and abundance of a species in each environment
describe the roles of photosynthesis and respiration in ecosystems and abundance of a species in each environment
identify examples of allelopathy, parasitism, mutualism and commensalism in an ecosystem and the role of organisms in each type of relationship
describe the role of decomposers in ecosystems
explain trophic interactions between organisms in an ecosystem using food chains, food webs and pyramids of biomass and energy
define the term adaptation and discuss the problems associated with inferring characteristics of organisms as adaptations for living in a particular habitat
identify some adaptations of living things to factors in their environment
identify and describe in detail adaptations of a plant and an animal from the local ecosystem
describe and explain the short-term and long-term consequences on the ecosystem of species competing for resources
identify the impact of humans in the ecosystem studied
How many organisms in an ecosystem
 Changes over time:
 Increases due to births and immigration
 Decreases due to deaths and emigration
Where an organism is found in an environment
Organisms are found where abiotic and biotic factors favour them
 Organisms are distributed where:
 Survival rate is high
 Predation is low
 Requirements for survival are met
Abiotic Factors Affecting Distribution and Abundance:
 Light
 Strength of wind
 Rainfall
 Temperature variations
 Topography
 Tides, currents and waves
 Water (amount, salinity, pH)
 Substrate
 Space and shelter
 Oxygen
Biotic Factors Affecting Distribution and Abundance:
 Availability of food
 Number of competitors
 Number of mates available
 Number of predators
 Number and variety of disease causing organisms
compare the abiotic characteristics of aquatic and terrestrial environments
Energy needed to sustain ecosystems is obtained from the sun
– This energy is captured by plants during photosynthesis
– Photosynthesis uses CO2 and water to make food - all organisms rely on this
– Respiration is the process by which cells obtain energy
– Organic molecules are broken down and energy is produced
– The organic molecules needed for respiration come from photosynthesis
– It all relies on the sun

Energy is never recycled - it requires constant input
– Photosynthesis powers ecosystems.
- Synthesis of complex molecules
– Growth of cells
– Repair and maintenance of old or damaged cells
– Active transport of materials
– Functioning of special cells that need extra energy
– Transport
Glucose + Oxygen ----> Carbon Dioxide + Water + Energy
- All living things need energy to remain alive
– Respiration is the breakdown of glucose with oxygen to release energy
- Aerobic means requiring oxygen
- glucose bonds - when they are broken, energy is released
- 50 different reactions - different enzyme

– ATP:
 Adenosine triphosphate (one adenosine attached to three phosphate groups)
 This is the energy carrier in all cells
 The energy produced by respiration is kept in these molecules
 The energy is stored in the phosphate bonds
 ADP (adenosine diphosphate) + P (phosphate) ----> ATP
– For every glucose molecule, 38 ATP molecules are produced
– ADP + P + Glucose + Oxygen ----> Carbon dioxide + Water + ATP
– 38ADP + 38P + C6H12O6 + 6O2 ----> 6CO2 + 6H2O + 38ATP
There are 2 stages in Respiration
 Occurs in cytoplasm
 Splits the 6-carbon glucose into two 3-carbon molecules (pyruvate - C3)
 2 ATP molecules are gained
 Does NOT require oxygen
Kreb’s Cycle:
 Occurs in the mitochondria
 Pyruvate is broken down into water and CO2
 36 ATP molecules are gained
 Oxygen is required
A population is a group of similar organisms living in a given area as a time
Process and analyse information obtained from a variety of sampling studies to justify the use of different sampling techniques to make population estimates when total counts cannot be performed
– Measuring Distribution:
 A transect
Measuring Abundance:
The quadrat method
Capture recapture method
= number captured x number recaptured
number marked in recapture

Number in quadrat number in total area
Area of quadrat total area

we will do these during excursion
Predator and prey population numbers are closely related and potentially unstable

-- The amount of food available
– The salinity of the water
– The amount of water available
-- The amount of space available
 This is the production by a plant of specific chemicals (allelo-chemicals)
which inhibit the growth of other plants around it
 examples such as Casuarina and eucalypts
 This is a relationship between two organisms where one benefits at the expense of the other organism
examples tapeworm and fleas
 A relationship between two organisms where both of them benefit
example - lichen. This consists of a fungus and an alga joined togeth
The fungi provides structure and the alga provides food
 A relationship between 2 organisms where only one benefits, and the other get no harm and no benefit
example barnacles and whales
Decomposers are the rubbish cleaners of the ecosystems
They feed on the left overs of other organisms, dead organisms and decaying organisms and their wastes.
They enable the materials of decomposition available to plants
They keep the biomass in circulation
if decomposers were not present there would be a build up of dead organisms
A FOOD CHAIN represents the flow of energy
FOOD WEBS are a complex set of interacting food chains
At every step of a food chain, energy is lost as heat and wastes
This is represented in an energy pyramid
At every step of the food chain, biomass (mass of organisms) is lost
Biomass is lost as undigested material and wastes
This is also shown in a biomass pyramid

An adaptation is a feature of a organism that makes it well suited to its environment and its lifestyle - always genetic
structural, physiological, behavioural

Problems associated with inferring characteristics of organisms include:
 If you do not know the environment an organism lives in, then saying a characteristic is an adaptation is just guesswork
 Sometimes, organisms gain features that are advantageous to its survival, but are a result of the organism’s live experience. This is not an adaptation, as adaptations are always genetically based
Soil erosion
Clearing of plants for buildings, roads or crops
Removal of soil, water or nutrients
Visual pollution example dumped rubbish
Introduction of weed species
Contamination of water or air by pollutants

Competition in ecosystems is the struggle between
organisms for the same resource
members of the same species or between members of different species
short-term, competition reduces the chance of survival and restricts the abundance of all competitors
long-term, one of the competitors will eventually be more successful

Example: river mangroves

Has salt glands on its leaves which excrete salt. This is an adaptation to living in a highly saline environment
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