8.2 A Local Ecosystem

1. The distribution, diversity and numbers of plants and animals found in ecosystems are determined by biotic and abiotic factors

DefinitionsEnvironment – all the factors that affect living thingsCommunity – a naturally occurring group of organisms that interact with each otherPopulation – a group of organisms of the same species living in a certain areaEcosystem – any environment containing living organisms interacting with non – living parts of environmentHabitat – the place where the organism lives

Compare the abiotic characteristics of aquatic and terrestrial environments

Abiotic features – the non – living factors or features of an environment (physical, chemical properties i.e. temperature, pH level, rainfall)Biotic features – the living components or biological features (members of the same species and members of other species

Abiotic Factors Aquatic Environments Terrestrial EnvironmentsViscosity High viscosity in water Air is less viscous than waterBuoyancy The buoyancy of water offers

support to both animals and plants, helps to maintain shape and to function is oceans depths

Buoyancy does not affect terrestrial flora and fauna. They need to be able to support themselves

Temperature Water heats up more slowly than air

Surface temperature varies far more on land than water

Pressure Water pressure increases with water depth

Air pressure decreases with height

Availability of Gases Gas availability in water depends on the temperature

Concentration of gases in higher

Availability of Water and Ions Organisms in water are surrounded by dissolved ions

Water availability varies

Light Penetration Decreases with depth Light intensity is high

Identify the factors determining the distribution and abundance of a species in each environment

Abundance – the abundance of a species means how many individuals there are at a specific time and areaDistribution – is where a species is found

Abiotic Factors Biotic Factors Light Abundance of food Wind and rainfall Number of competitors Temperature Number of mates Effect of topography Number of Predators Tide, currents and waves Diseases Salinity, pH and water availability

Measuring Abundance Direct counting Using sample area as a guide Estimate of percentage cover Quadrat

Measuring Distribution Profile sketch Transect Surface map Observations Radar, cameras or tagging

Quadrats

Number in the quadrat Number in total area Area of the quadrat Total area

Capture marking – recapture

Estimated Population = number of animals tagged x number of animals recaptured Average number of tagged animals recaptured

Describe the roles of photosynthesis and respiration in ecosystems

Photosynthesis is the process by which plants cells capture energy from sunlight and use it to combine carbon dioxide and water to make sugars and oxygen.Photosynthesis provides nutrients and energy to organisms herbivores, carnivores and so energy and materials are passed from organism to organism.

CO2 + H2O C6H12O6 + O2

Carbon dioxide + water Glucose + Oxygen

Respiration is the process where the cells obtain energy, and break down sugars to produce carbon dioxide and water and energy is then released Respiration occurs in the mitochondria of cells.Respiration is a process carried out in all living cells to release energy for living, respiration changes glucose into chemical energy.

C6H12O6 + O2 H2O + CO2 + energy/ATPGlucose + Oxygen Water + Carbon dioxide + energy/ATP

Identify the general equation for aerobic cellular respiration and outline this as a summary of a chain of biochemical reactions

Aerobic Respiration process whereby glucose is broken down into carbon dioxide and water using oxygen and releasing energy.ADP – Adenosine DiphosphateATP – Adenosine Triphosphate

When ATP is broken down it becomes ADP which releases a large amount of energy.

ADP + Glucose + Oxygen Carbon dioxide + Water + ATP (energy)

Respiration occurs in 2 stages: - First stage, in the cytoplasm of the cells, 2 molecules of ATP is produced, this occurs with

anaerobic respiration. Second stage, in the mitochondria of the cells 36 molecules of ATP is produced, occurring

with aerobic respiration.Respiration involves a series of chemical reactions. It occurs as a sequence of 50 different reactions, each catalysed by a different enzyme. The bonds in the organic molecules, such as sugar are broken releasing small amounts of chemical energy; this energy is transferred to the energy carrier molecule

A P P P A P P

ATP. The energy released is used to convert ADP to ATP so that the energy can be used all around the body. 40% of the energy in glucose is converted into ATP the rest is lost as heat.

Identify uses of energy by organisms

Respiration is a process carried out in all living cells, this energy is used For growth and repair For movement To keep organs working For chemical reactions For movement of substances in the organism To synthesise compounds

2. Each local aquatic or terrestrial ecosystem is unique

Examine trends in population estimates for some plant and animal species within an ecosystem

Population of organisms do not remain at a constant level in an ecosystem, but sometimes the population increases dramatically this is called a population explosion. Population may also decline due to, diseases, predation, competition from other species and human impact on the ecosystem and sometimes the organisms become extinct because of these factors.

Outline factors that affect numbers in predator and prey populations in the area studied

Predator – An organism that obtains food by killing other organismsPrey – An organism that is killed for food

Size of ecosystem Diseases Availability of food Migration Reproduction Human activity Competition

Identify examples of allelopathy, parasitism, mutualism and commensalism in an ecosystem and the role of organisms in each type of relationship

Interactions Definition ExampleSymbiosis Species that live together in

communities, and interact with each other

Parasitism One species benefits and the other is harmed because of its presence

Leech and Human, leech sucks human blood while the human body is harmed

Mutualism Where two species interact with each other and benefit from both species

Tick bird and Zebra, tick bird removes parasites from the zebra and is also in access to food

Allelopathy The chemical inhibition of one species by another

Casuarina, it produces metabolites that prevent growth of plants in the same area

Commensalism One species gains and the other has no effect

The remora and shark, the remora is in access to food while the shark makes no attempt to feed on it

Describe the role of decomposers in ecosystems

Decomposers are organisms that absorb nutrients from dead tissue or waste products and returns organic material to the soil. They also make materials produced by decomposition available to plants, which is then recycled into the food chains. Bacteria and fungi are usually the main decomposers in an ecosystem.

Explain trophic interactions between organisms in an ecosystem using food chains, food webs and pyramids of biomass and energy

Trophic Interaction – Feeding relationship between organismsTrophic Level – Feeding level of an organismIn a natural environment, energy from sunlight enters through the process of photosynthesis then flows onto other organisms via food chains and webs. Photosynthesis can change the sun’s energy into chemical energy for other organisms.

Food ChainsA food chain illustrates what organisms eat what; the arrows indicate “is eaten by” and usually the food chain starts off with a producer.

Food WebsA food web is many food chains joined together; it shows the trophic interactions, energy flow of all living things in an ecosystem.

Producer – an organism that makes its own food, autotrophsConsumer – an organism that feeds on another living thing, heterotrophsHerbivore – a consumer that only feeds on plant materialCarnivore – a consumer that only feeds on animals

Biomass PyramidBiomass – The measure of the mass of all organisms at a particular trophic levelIn each transfer of energy about 90% is lost as heat and 10% is transferred to the consumer.

Energy Pyramid- Represents each trophic level- The amount of energy lost with each level

Define the term adaptation and discuss the problems associated with inferring characteristics of organisms as adaptations for living in a particular habitat

AdaptationThe area where an organism lives is because they survive in that habitat. Organisms have features that help them adapt to the environment which helps them survive. There are 3 types of adaptations:

1. Structural Adaptations – This refers to the physical structure of the organism2. Physiological Adaptations – This refers to the way the organism functions3. Behavioural Adaptations – This refers to the behaviour, how organisms respond to

its environment

CarnivoresHerbivoresProducers

Producers1st Order consumer2nd Order consumer3rd Order consumer

The word adaptation should be used carefully, human observations of characteristics of organisms come from human perspectives it not to say that a characteristic is an adaptation and an animal or plant in a specific location does not mean it has special adaptations to the habitat.

Identify some adaptations of plants and an animal from the local ecosystem

Mangroves KangaroosSupport and Movement Anchored by complex root

systems in the groundWell muscled hind legs are made for travelling at high speeds

Gaseous Exchange Gaseous exchange occurs through the aerial root’s tips

Use lungs for respiration

Water balance Mangroves control their salt level through:

Cells maintain higher concentrations of cell solutes

Secrete salt from leaves

Sufficient leaves will help them survive

Internal temperature Its leaves have thick cuticle and are hard and leathery, prevents water loss and wilting in hot weather

They seek shade of trees and bushes to maintain their body temperature

Obtaining light It is abundant to light for photosynthesis

They are nocturnal animals but are active in the early morning and early evening

Reproduction The seeds germinate before they are dropped from their parent plant to insure a root system for rapid growth

Marsupial process of reproduction

Describe and explain the short – term and long – term consequences on the ecosystem of species competing for resources

Short term- Availability of resources decreases- The growth of the population may decrease- If the population decreases the availability of food may increase

Long term- Degradation of the environment- Diversity of organism will be reduced- Extinction of species- Evolution

Identify the impact of humans in the ecosystem studied

- Land clearance and habitat destruction- Erosion and loss of soil- Salination and desertification- Pollution of air, water and soil- Fertilisers and pesticides- Loss of biological diversity- Exploitation and depletion of natural non – renewable resources- Production of poisonous materials- Introduction of new species of fauna and flora