relationship of organisms 270410
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Relationship of Organisms
With one another and with the environment
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Learning Objectives (chapter 21)
You should be able to:
State the principal source of energy input to biologicalsystems
Describe the non-cyclical nature of energy flow Establish the relationship of the following in food webs:
producer; consumer; herbivore; carnivore; decomposer;food chain
Describe the energy losses between trophic levels and
infer the advantages of short food chains. Describe the importance of the carbon cycle.*
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Lesson Objectives (chapter 22)
Describe the effects of Man on the ecosystem with emphasis
on examples of international importance (tropical rainforests,
oceans, important rivers)
Evaluate the effects of:
Water pollution by sewage and by inorganic waste Air pollution by sulphur dioxide and oxides of nitrogen (acid rain)
Pollution due to insecticides
Discuss reasons for conservation of species with reference to
maintenance of biodiversity, management of fisheries AND
management of timber production
Discuss reasons for the recycling of materials with reference
to named examples
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Newsflash!!
Malaria once infected nine out of ten people in Brunei Darussalam. In 1955, theWorld Health Organisation (WHO) began spraying the insecticide dieldrin to kill the
malaria-carrying mosquitoes. The program was so successful that the dreaded
disease was almost eliminated. Then strange things started to happen
The dieldrin killed other insects, including flies and cockroaches, living in the
houses. Then the geckos which lived in the houses died after eating the dead
insects. Then cats began dying after eating the dead lizards. Without cats, the ratsflourished. With the rats came the plague, carried by fleas on the rats. The situation
was only brought under control when WHO parachuted healthy cats onto Brunei.
The roofs of the houses began to fall in. The dieldrin had killed wasps and other
insects that fed on a type of caterpillar that either avoided or was not affected by
the insecticide. With most of its predators eliminated, the caterpillar population
grew rapidly. The caterpillars ate their favourite foods, the leaves used to thatch theroofs of the houses.
Eventually, the numbers of predatory insects recovered and the spraying
programme was a success story. But it does show the unpredictable results that
can happen when humans interfere with ecosystems.
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Activity Time!
Can you list the various ways in which the organisms in the newsreport interacted with each other?
Flies &
cockroaches
Geckos Cats Rats
Wasps & other
insectsCaterpillars
LeavesFleas
Malaria-carrying
MosquitoesHumans
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Answers:
Flies &
cockroachesGeckos
Cats
Rats
Wasps & other
insects
Caterpillars Leaves
Fleas
Malaria carrying-Mosquitoes Human blood
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What is Ecology? Ecology is the study of interactions
among organisms, and between
organisms and the physical and chemical
factors making up their external
environment.
The natural environment is made up of abiotic and biotic factors found in
its surroundings that affect it:
Abiotic factors:
Non-living factors which make up the physical environment
Determines the type of living organisms found in the habitat
Biotic factors:
all the living organisms which an organism interacts with in its
habitat.
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Ecological Terms
A place where an organism lives.
A group of individuals of the same species occupying a given area.
Consists of populations of plants and animals living together and
interacting with one another under the same environmental conditions.
Formed by the interactions of communities and their physical environment.
The function of an organism or the role it plays in the habitat.
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Abiotic/Physical
Environment
Biotic
1. Light
2. Temperature
3. Water
4. Oxygen
5. Salinity (Salt Concentration]
6. Acidity/alkalinity (pH)
RelationshipsRelationships
Interdependence between
various populations in any
community
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Light intensity
Green plants exist only where is an adequatesupply of sunlight.
It affects the distribution and growth of plants and
animals.
Adaptation of PLANTS to light intensity:
In areas where light penetration is poor,
Trees grow taller
Some plants make use of tall trees to reach
sunlight, e.g. climbers
Too much of sunlight, Retards elongation of stem
Dense covering of hairs on leaf epidermis to
screen off excess light and heat
a layer of thick-walled cells known as hypodermis
found beneath the epidermis
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Light intensity
Animals need light in order to
see, move, find food and detect danger.
Bats hanging in a
cave
Special adaptations:In areas like caves where there is a
lack of light,
Bats have a highly sophisticated
sense of hearing
By emitting sounds that bounce off
the objects in their path, which send
echoes back to the bats.
Bats detect the echoes and are able
to determine the size and distance of
the objects.
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TemperatureTemperature affects the physiological activities of plants and animals.
For many flowering plants,
These are some adaptive features to survive the seasonal changes:
The shedding of leaves to reduce water loss
Formation of seeds that are resistant to drought, heatand cold so that they are able to survive the
unfavourable seasons
Underground storage organs
Temperature affects also the metabolic activities of
the organisms because it indirectly affects rate of
enzyme action on a substrate.
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During winter, polar bears curl up in temporary
caves or find natural shelter to keep warm.
They hibernate and live off their stored body
fats which were accumulated when food was
plentiful.
Temperature
More examples
How do penguins survive the cold?
Thick layers of fat help to insulate
them from the cold.Feathers help to trap air which is a
poor conductor of heat.
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Cacti
thick waxy cuticle
leaves reduced to spines
few stomata
fleshy stems to store water
green stems which take over function
of photosynthesis from leaves
Water Essential for life.
Must be present in the environment of every organism.
Medium for aquatic plants and animals
Availability of water depends on the distribution of rainfall in a year.
What are Xerophytes?
Plants which can live in conditions of prolonged
drought in their habitat.
Examples: Cactus, Casuarina, marram grass, etc.
To reduce rate of
transpiration/ waterloss from leaf surface
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Adaptations of plants to dry habitats
In marram grass:
Rolled up leaf to reduce surface area
exposed to surrounding.
Deeply grooved inner leaf surface with
stomata
Spines/hairs to trap water vapour
diffusing out of stomata.
Increase humidity around the stomata
Reduces the rate of transpiration
For the plant Casuarina,
The leaves are reduce to tiny sheaths
at the stem nodes
Long green stems have stomata that liein grooves protected by minute hairs
Leaves
Stem
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WaterWhat are Hydrophytes?
Plants which live in water or very wet places.Examples of hydrophytes:
Hydrilla (completely submerged)
Water lily (partially submerged)
Water hyacinth (free floating)
Adaptive features to wet habitat:
Large surface area of leaf for
photosynthesis
Air spaces in leaf to help the plant
float on water.
Vascular bundle poorly developed
as water enters the plants cell directly
Upper surface of leaf protected by
waterproof cuticle to prevent water
from blocking the stomata
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Water
Mangrove plants such as Avicennia, have roots
buriedin oxygen-poormud.
Adaptations:
special breathing roots calledpneumatophores arise from root system out of
the mud surface.
Has openings/pores which allow oxygen to
pass downwards to the root system.
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Adaptations of animals to dry habitats.
CamelsAdaptive features:
Able to survive without
water for weeks
Humps store fats whichcan be broken down to
provide energy and
metabolic water during
respiration.
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Oxygen Required forrespiration
What is the difference between
Land animals and plants vs. aquatic animals and plants
Oxygen from air (Land)
Oxygen dissolved in water (Aquatic)
Exceptions? For example: Mudskipper.
Lives in water but is able
to obtain oxygen from air.
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Marine aquarium
(similar to sea environment)
Higher salt content
Salinity (salt concentration)
Important factor for aquatic organisms
Freshwater aquarium
(similar to pond environment)
Lower salt content
Freshwater plants have rigid cellulose cell
walls to prevent from bursting.
Protozoa such as Amoeba have contractile
vacuoles to remove excess water entering by
osmosis.
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Kidney and accessory organs play a role in maintaining constant internal
environment. But how do they do it?
Salinity
Other adaptations:
Saltwater fish have waterproofcoat which consists of:
Closely fitting scales
Slimy mucous material
Freshwater fish:
Excessive water entering body cells
by osmosis Salt loss from body cells by diffusion
Marine Fish
Water loss from body cells
Salt moving into body cells from
sea environment.
Freshwater fish: Kidney reabsorbs salts and produces
large amounts of dilute urine
Cells in gills uptake salt from water
Marine Fish:
excretes salts and small amounts ofwater, producing highly concentrated
urine
Cells in gills secrete salt into
surroundings
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pH (acidity/alkalinity)
pH value of water in soil, ponds or sea affects the kind of
organisms that live in these habitats. Affects the enzymatic activity of the cells in the organisms.
For example, pineapples and cotton plants grow best in acidic soil
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pH (acidity/alkalinity)
Sea water Slightly alkaline (pH~8)
Remains more or less constant
Freshwater pH varies from one region to another
Dependent on bicarbonate ions present in the water.
In the day, photosynthetic activity of the plants use upcarbon dioxide in the water making if more alkaline.
At night, no photosynthesis takes place, aquatic plantsrespire producing carbon dioxide which is dissolved inwater, making water more acidic.
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The EcosystemThe Earth is one giant ecosystem with all living things interacting with the
environment and each other, using and reusing the finite resources to live.
It is a self supporting unit with the following components:
A constant source of energy SUNLIGHT
Food producers
Food consumers
Decomposers
http://www.open2.net/diyscience/ecosphere/index.html
An ecosystem requires both energy and
material (inorganic nutrients) to sustain itself.
Energy enters an ecosystem from outside
and flows through in a non-cyclic manner.
Materials are obtained from physical
environment and flow through the
ecosystem in a cyclic manner.
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Energy flow:
Sun PlantsAnimals Decomposers
Trapped by
chlorophyll
Plant dies
Animal dies
Eaten by
Light energyChemical energy
Chemical energy
Ecosystem
One-way flow of energy in an ecosystem
Heat energy Heat energy Heat energy
Chemical energy
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Non-cyclical nature of energy flow
When plants trap suns energy and pass it on to the
other living organisms
Only 1% of sunlight enters the ecosystem which is trapped
by plants All the energy is eventually lost to the non-living
environment as heat energy Heat is considered a waste energy as organism cannot use it
Heat cannot reenter the ecosystem Energy flow is thus one way (non-cyclical) as it is not recycled.
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Understanding Food chains and food webs
Organisms in an ecosystem can be grouped according to their functions
Organisms Functions
Producers Mainly green plants that manufacture complex organicfood substances from simple inorganic raw materials
via photosynthesis
Consumers
Primary Consumers
Secondary/Tertiary
Consumers
Organisms that obtain energy from other organisms onwhich they feed.
a) Herbivores Feed directly on plants
b) Carnivores Feed on other organisms
c) Scavengers Feed on dead/decaying organisms
d) Parasites Feed on living tissues of organisms
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Understanding Food chain and webs
Organisms Functions
Decomposers Feed on dead organisms
Breakdown complex nutrients locked up in them
into simple inorganic substances which are returned
to the non-living environment to be reused.
Examples of decomposers are fungi
and bacteria
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Food chain A series of organisms
through which energy is
transferred in material
form (food) constitutes
a food chain.
Each stage in the food
chain is a trophic level.
Trophiclevel 1
Trophiclevel 2
Trophiclevel 3
Trophiclevel 4
Trophiclevel 5
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Food webs A complex feeding
relationship within acommunity where two ormore food chains arelinked by eating differenttypes of plants and animals,
a consumer has a betterchance of survival.
If one food sources are
destroyed, other food sourcesare available
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Ecological Pyramids Pyramid of energy
Represents the rate of energy flow in a food chain
Always upright ( i.e. broad base tapering to narrow apex) Shows that amount of stored energy gets smaller at each tropic level.
Energy transfer:
Only 10% of chemical energy
is converted into new tissueand made available for the next
link in the food chain.
- Energy is almost completely
dissipated into surroundingsby the 4th or 5th trophic level.
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Ecological Pyramids
Pyramid of numbers
Can you name some other
organisms that could be used for
each of the levels in the diagram
below?
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Ecological pyramids Pyramid of biomass
Since the amount of water present within the tissues of different organismsvaries, biologists use the dry mass of the organism for comparison since it is
believed that dry mass more closely reflects the actual amount of"living
matter" in the organism. The dry mass is known as biomass.
In a grassland environment, 10,000 kg of grass and other producers (dry mass)
should support about 1,000 kg (dry mass) of grasshopper and other plant eatinginsects.
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Ponder this!What are the advantages of having a shorter food chain?
Reduce the amount of energy lost through trophic levels
More energy is available at the beginning of the food chain
It seems like
It is more efficient to eat green plants for food
Less efficient if crops are fed to cattle and then consumed when manfeed on cattle.
But why dont we all become vegetarians instead? Man is unable to digest cellulose
Cattle can turn energy in cellulose into energy in protein and fat. (this
can be digested by man) Selection of crops:
Important to feed on crops which man can digest directly e.g. soyaproducts which are high in protein.
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