INTERDEPENDENCE of LIVING ORGANISMS
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© Hans pfletschinger
The picture shows a bee visiting a sage flower
It provides an example of interdependence
The bee is dependent on the flower for its nectar
The flower is dependent on the bee for pollination
(You will need to have an understanding of respiration and photosynthesis to follow this slide show)
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A food chain
(1) The caterpillar eats the leaf….
(2)....the blue tit eats thecaterpillar...
(3)....the kestrel eats theblue tit.
This is an example ofa food chain
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1
2
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Animals depend on plants for foodThe food chain
Cabbage
Snail
Thrush
Sparrow hawk
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The sparrow hawk does not depend directly on plants but it does depend on thrushes, which eat snails, which eat cabbages.
So the sparrow hawk is indirectly dependent on plants
Food chains are never so simple as the ones in slides 3 and 4
Sparrow hawks do not feed exclusively on thrushes; thrushes eat worms as well as snails; snails eat many plants, not just cabbages
A more accurate picture is given by a food web
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fox owl stoat
rabbit
rat
beetle
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QuestionWhat is the most likely outcome of a severe fall in the numbers of foxes?
(a) Increase in rabbits, decrease in rats, increase in owls
(b) Increase in rabbits,increase in stoats, increase in vegetation
(c) Decrease in rabbits, increase in beetles, increase in vegetation
(d) Increase in rabbits, increase in owls, decrease in vegetation.
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All organisms depend on sunlight
SUNLIGHT
Wheat grains
Flour
Bread
Cow
Milk
Cheese
Nectar
Bees
Honey
Photosynthesis in wheat
Photosynthesis in grass
Photosynthesis in flowering plants
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Pyramid of numbers
Example of a food pyramidThe width of each band represents the
number of organisms
Plant leaves
Caterpillars
Blue tits
Owl
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But wait!
• Pyramids may be inverted, particularly if the producer is very large (e.g. an oak tree).
So…
PYRAMIDS OF BIOMASS, which represent the biomass (n° of individuals x mass of each
individual), should solve the scale and invertion problems of the pyramid of numbers.
Dependence on oxygen and carbon dioxide
Animals need oxygen for respiration
Plants produce oxygen in photosynthesis
Animals produce carbon dioxide in respiration
Plants use up carbon dioxide in photosynthesis
The process of decay uses up oxygen and produces carbon dioxide
This interdependence is represented by the Carbon Cycle
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Atmospheric carbon dioxide
Production of carbon
dioxide
Uptake of carbon
dioxide
Burning of fuel: wood, coal, oil and gas.
Respiration in allorganisms
Decay of organic matter
Photosynthesis inplants
Absorption by the oceans
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12The carbon cycle
Dependence on bacteria
-Most bacteria are beneficial
-They break down dead organisms into simpler substances
-Soil bacteria make mineral salts available to plants
-Bacteria and fungi are called decomposers
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Recycling and the role of decomposers
PRODUCERS green plants
CONSUMERS animals
DECOMPOSERSbacteria and fungi
SOILminerals and humus
sunlight
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Decomposers
• If it were not for bacterial and fungal decomposition, we would be knee deep in dead leaves after a few years
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Conclusion
The inter-relationships between all living organisms are so complex that
any disturbance in the patterns of interdependence can have far-
reaching consequences
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Question 1Which of the following might be genuine food chains?
(a) zebra - lion - giraffe - leopard - antelope
(b) grass - grasshopper - lizard - snake - eagle
(c) aquatic vegetation - hippopotamus - tick - oxpecker bird - tawny eagle
(d) stickleback - pondweed - minnow - pike - kingfisher
Question 2
Which of these organisms might be classed as ‘producers’?
(a) mosses
(b) fungi
(c) trees
(d) earthworms
Question 3Which of these statements is most accurate?
In bright sunlight a green plant will be...
(a) photosynthesising only
(b) respiring only
(c) photosynthesising and respiring
(d) taking in oxygen and giving out CO2
Question 4
Which of these increase the concentration of carbon dioxide in the atmosphere?
(a) respiration
(b) photosynthesis
(c) combustion
(d) decay