Transcript Biology 12

Biology 12
Matter and energy
• In most natural ecosystems, matter cycles
and is re-used
• Energy flows and is lost
• At each trophic level most of the energy is
lost in respiration
Water cycle
Condensation
Precipitation
Evaporation
Transpiration
Run off
Surface water
Water uptake
Ground water
Water cycle
Carbon cycle
.
Photosynthesis
Air
Respiration
Respiration
Combustion
Consumers
Producers
Fossilisation
Wastes
Decomposers
Fossil fuels
Carbon cycle
Nitrogen cycle
Fertilisers and
lightning
Atmospheric
Nitrogen
Nitrogen fixers
Animal protein
Dead organisms
& wastes
Denitrifying bacteria
Ammonia
Root nodule
bacteria
Nitrifying bacteria
Nitrates
Plant protein
Nitrogen cycle
Phosphorus cycle
Sedimentation
Plants
Soil and water
Erosion
Rocks
Animals
Decomposers
Phosphorus cycle
Energy in ecosystems
Energy leaving as waste heat
Energy available from
previous level
Respiration
Energy lost in wastes
Energy used for new growth
Measuring energy flow
Sun outputs ~ 40 000kJ per day
38 000kJ per day is reflected and not used
Heat energy lost due to respiration
1200 kJ
2 000kJ per day
is used by plants
220 kJ
320 kJ
32 kJ
40 kJ
Energy used for growth and thus available to next level
60 kJ
8 kJ
480 kJ
548 kJ
Energy in dead matter and wastes
Measuring energy flow
• Productivity - rate at which an ecosystem accumulates
mass or energy – biomass/unit area/time period (eg
kg/m2/day) or energy/unit area/time period (eg
kJ/m2/day)
• Biomass – dry weight of organisms found in a trophic
level - mass/unit area (eg kg/m2) or energy/unit area (eg
kJ/m2)
• Gross primary productivity – how much solar energy is
fixed as chemical energy by producers (ie measure of
energy trapped by photosynthesis
• Net primary productivity – amount of energy available
once respiration has occurred
Pyramids
• These show numbers of organisms, or
energy/mass available at each trophic level
• The 4 types are numbers, size, biomass and
productivity
Drawing pyramids
Number of
organisms
Size of organism
Biomass (g Carbon/m2)
New tissue produced
(g/day)
Producer
1
5m
150
6
1st order
consumer
500
5mm
15
8
2nd order
consumer
4
20 cm
1.5
0.3
3rd order
consumer
40
1 mm
0.15
0.01
Trophic
status
Organism
producer
number
<5000 mm
2nd order consumer <500 mm
<50 mm
3rd order consumer
2nd order consumer
1st order consumer
<5 mm
1st
order consumer
producer
biomass
3rd order consumer
2nd order consumer
1st
size
3rd order consumer
2nd order consumer
3rd order consumer
1st order consumer
order consumer
producer
producer
productivity
<1 mm
Short answer 2006 31a & b
The following diagram shows a food web occurring in a eucalypt woodland in Australia
a) Is Acrida a plant or an animal? Using information the food web, explain your answer
b) Which species, robin or ground beetles, will have the greatest biomass? Explain your
answer by reference to the food web.
Short answer 2006 31a
The following diagram shows a food web occurring in a eucalypt woodland in Australia
a)
Is Acrida a plant or an animal? Using information the food web, explain your answer
Most likely animal
• Feeds off gum trees
• Consumer/heterotroph (1 mark each)
• Wren (predator of Acrida) is a second order consumer
• Could be a parasitic plant
Short answer 2006 31b
The following diagram shows a food web occurring in a eucalypt woodland in Australia
b) Which species, robin or ground beetles, will have the greatest biomass? Explain your answer
by reference to the food web.
Any four of:
• Probably ground beetles
• Robins eat ground beetles
• Robins convert some of the beetle biomass into heat
• Only about 10% of ground beetle biomass becomes robin biomass
• Ground beetles are a lower trophic level/lower in the food chain
• Can argue that robins eat earthworms as well as ground beetles, so their biomass may be more
than would be expected on a diet of ground beetles alone.
Short answer 2006 31c
Indicate whether each of the following statements about the food web is TRUE or FALSE.
Give a reason for each answer.
(i) Energy is constantly lost from the food web.
(ii) Some of the biomass in the ground beetles may eventually be found in the bodies of
spiders.
Short answer 2006 31c
Indicate whether each of the following statements about the food web is
TRUE or FALSE. Give a reason for each answer.
(i) Energy is constantly lost from the food web.
True - All organisms lose heat in respiration/metabolism/metabolic
processes so energy is constantly lost.
(ii) Some of the biomass in the ground beetles may eventually be found in
the bodies of spiders.
True - Beetles die, decompose and inorganic material/organic
material/matter is recycled (possibly into spiders’ bodies)
Short answer 2006 31d & e
d) In some links in the food web, dozens, even hundreds, of species are grouped as one (eg
mites). Give two reasons why this has been done.
e) The gum trees in the community were sprayed with insecticide to reduce damage caused
by gum moths. The insecticide is not harmful to vertebrate animals at the rate it was sprayed.
There were no immediate impacts on other species, but after three months the frogmouths and
quolls began to die. What might be causing their deaths?
Short answer 2006 31d
d) In some links in the food web, dozens, even hundreds, of species are
grouped as one (eg mites). Give two reasons why this has been done.
2 marks/dot point in this question
• They occupy the same niche in the food web/consume the same food/have
the same predators
• If all species were named the food web would be too complex
• Not all the species occurring in the food web will be known
• Only the most abundant species are shown
Short answer 2006 31e
e) The gum trees in the community were sprayed with insecticide to reduce damage caused by
gum moths. The insecticide is not harmful to vertebrate animals at the rate it was sprayed.
There were no immediate impacts on other species, but after three months the frogmouths and
quolls began to die. What might be causing their deaths?
Any four points from:
• Insecticide is concentrated along the food chain (biomagnification). Give two marks if the concept
is described and biomagnification used, no marks if just biomagnification written.
• Each link in the food chain ingests a lot of the organism below it and accumulates all the pesticide
in those organisms.
• Therefore the pesticide increases at higher levels in the food chain
• At the higher levels the accumulated pesticide becomes toxic
• The insecticide is not biodegradable.
Extended answer 2004 36(c)
Explain the concept of an ecosystem, describing
the major components. Explain how ecosystems
are interlinked to form a biosphere.
Extended answer 2004 36(c)
Explain the concept of an ecosystem, describing the major components. Explain how
ecosystems are interlinked to form a biosphere.
•
ecosystem is all organisms in an area and the physical environment with which they
interact
• plant components (producers) described
• animal components (consumers) described
• role of decomposers
• non-living components described
• the energy source is the sun
• organisms and non-living surroundings are linked through nutrient cycling
• a fully annotated diagram including the above points (max 6 marks)
Maximum 6 marks
• biosphere is all the ecosystems of the earth
• energy flows, nutrients cycle
• biomass pyramids can be used to show these relationships
• organisms are linked via food chains and food webs
• matter may flow between ecosystems
• organisms may move between ecosystems
• pollutants may move between ecosystems
Maximum 6 marks
Extended answer 2004 37(d)
Humpback whales weigh up to 65,000 kg, about as much as 70 mid-size
cars. They primarily eat small crustaceans called krill which they filter
from the seawater using brush-like plates called baleen, located on
each side of their upper jaw. The humpback whales are at the end of a
very short food chain in which small autotrophs (phytoplankton) are the
producers, krill are first order consumers and the whales are second
order consumers.
(i) From your knowledge of energy flow in ecosystems, suggest why
humpback whales are able to grow so large.
Extinct large sharks called Megalodon are believed to have preyed on
primitive whales.
(ii) Would the biomass of Megalodon have been larger, smaller or about the
same as the biomass of its prey? Explain your answer.
Extended answer 2004 37(d)
Humpback whales weigh up to 65,000 kg, about as much as 70 mid-size cars.
They primarily eat small crustaceans called krill which they filter from the
seawater using brush-like plates called baleen, located on each side of their
upper jaw. The humpback whales are at the end of a very short food chain in
which small autotrophs (phytoplankton) are the producers, krill are first order
consumers and the whales are second order consumers.
(i) From your knowledge of energy flow in ecosystems, suggest why humpback
whales are able to grow so large.
• all energy comes from the sun
• producers fix solar energy, but efficiency is low
• consumers gain energy from breaking down ingested organic compounds
• at each step in a food chain, only 10% of energy is transferred
• the longer the food chain, the less energy at the end
• biomass reduces at each step in a food chain
• the short food chain involving humpback whales means more energy at the end
and more biomass can be sustained
Maximum 6 marks
Extended answer 2004 37(d)
Humpback whales weigh up to 65,000 kg, about as much as 70 mid-size cars. They
primarily eat small crustaceans called krill which they filter from the seawater
using brush-like plates called baleen, located on each side of their upper jaw.
The humpback whales are at the end of a very short food chain in which small
autotrophs (phytoplankton) are the producers, krill are first order consumers and
the whales are second order consumers.
Extinct large sharks called Megalodon are believed to have preyed on primitive
whales.
(ii) Would the biomass of Megalodon have been larger, smaller or about the same
as the biomass of its prey? Explain your answer.
• smaller biomass than the prey
• only 10% of the energy in the prey is transferred to the Megalodon
• 90% of energy is lost as heat
• if Megalodon had alternative prey to whales, then it might not have a smaller
biomass than whales
• labelled food web indicating alternative food sources for Megalodon
• labelled biomass pyramid indicating lower Megalodon biomass
Maximum 6 marks