Download Unit 2: Multi-cellular organisms

Charleston Academy
Biology National 5
Unit 3: Life on Earth
Revision: What you should know
(From Torrance (2013) National 5 Biology)
Key areas 1-3
Biodiversity and the distribution of life
Energy in ecosystems
Sampling techniques and measurements
Word bank
1.
abiotic
ammonium
animals
bacteria
base
biomass
biomes
biotic
chain
climate
community
consumer
decomposers
decreases
ecosystem
energy
heat
human
interspecific
intraspecific
level
light
many
meters
niche
nitrification
nitrogen
numbers
pH
pitfall
predation
protein
pyramid
quadrats
rainfall
sampling
temperature
transfer
valid
Biodiversity in an ecosystem can be affected by BIOTIC and abiotic factors
and HUMAN influences that can increase or decrease it.
2.
Biotic factors such as grazing and PREDATION are caused by living things;
abiotic factors such as pH and TEMPERATURE are non-living.
3.
Various large regions of the Earth, distinguished by their CLIMATE and native
plants and ANIMALS, are called BIOMES. Their global distribution can be
affected by RAINFALL and temperature.
4.
An ECOSYSTEM is made up of a community of living organisms and the nonliving factors with which they interact. A NICHE is the role that an organism
plays within a COMMUNITY.
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5.
About 90% of ENERGY is lost at each level in a food CHAIN as undigested
material or as HEAT or during movement. Some of the energy in waste
material is gained by the ecosystem’s DECOMPOSERS.
6.
A pyramid of NUMBERS illustrates the numerical relationship between the
organisms in a food chain, with the producer (the most numerous) at the BASE
and the final CONSUMER (the least numerous) at the top.
7.
A pyramid of BIOMASS shows that the producer at the base has the
greatest biomass and that this DECREASES, level by level, to the final
consumer, which has the smallest biomass.
8.
A PYRAMID of energy illustrates the energy content at each LEVEL in a food
chain and the TRANSFER of energy from one level to another.
9.
NITROGEN is cycled round ecosystems. Nitrate absorbed by plants is made
into plant PROTEIN, which becomes converted to animal protein on being
consumed.
10. Several different types of BACTERIA play essential roles in the nitrogen
cycle by bringing about the processes of NITRIFICATION, nitrogen-fixation
and the decomposition of wastes to AMMONIUM compounds.
11.
When competition for the same resource(s) occurs between individuals of
different species in an ecosystem, it is called INTERSPECIFIC competition
and when it occurs between individuals of the same species it is called
INTRASPECIFIC competition.
12. Biologists investigate an ecosystem’s community by SAMPLING its plants and
animals. To do this, they often use quantitative techniques such as PITFALL
traps and QUADRATS.
13. For sampling to give a VALID representation of the community, MANY
samples must be taken and mean results calculated.
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14. An ecosystem is affected by many ABIOTIC factors including LIGHT
intensity, temperature, moisture content and pH. These can be measured using
appropriate METERS and probes linked to computer software.
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Key areas 4-5
Adaptation, natural selection and evolution
Human impact on environment
Word bank
adaptation
adapted
advantage
alleles
bacteria
biological
bloom
disadvantage
enemies
fatal
fertiliser
fittest
genetic
increase
indicator
intensive
isolation
mutagenic
mutation
non-biodegradable
natural
offspring
oxygen
quality
radiation
random
selection
speciation
toxicity
yield
1.
A MUTATION is a change in the structure or composition of an organism’s
GENETIC material. It may confer an advantage or a DISADVANTAGE on the
organism or be neutral and not affect it.
2.
Mutations occur spontaneously and at RANDOM but rarely. They are the only
source of new ALLELES.
3.
Rate of mutation can be increased by MUTAGENIC agents such as
RADIATION and certain chemicals.
4.
An inherited characteristic that makes an organism well suited to survive in
its environment is called an ADAPTATION.
5.
The members of a species produce far more OFFSPRING than the
environment can support. This leads to a struggle where only the FITTEST
survive.
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6.
Those individuals best ADAPTED to a changing environment pass on the genes
that confer a selective ADVANTAGE to their offspring. The less well adapted
members die. This weeding out process is called NATURAL selection.
7.
SPECIATION occurs when a population becomes isolated for a very long time
and natural SELECTION takes a new direction. Gradually the group becomes
adapted to environmental conditions that differ from those that affected it
before ISOLATION.
8.
The human population continues to INCREASE rapidly and this needs to be
matched by an increase in food YIELD.
9.
When FERTILISER from farmland leached into watercourses or lochs it may
over-enrich the water and cause formation of an algal BLOOM. When the
algae die, the decomposer BACTERIA that act on them undergo a population
explosion and use up the water’s dissolved OXYGEN supply during respiration.
10. Molecules of pesticides that are NON-BIODEGRADABLE can accumulate in
the bodies of organisms. This leads to an increase of TOXICITY along food
chains, which may be FATAL to the final consumers.
11.
A species that by its presence indicates the QUALITY of the environment is
called an INDICATOR species.
12. Attempts are made to balance the adverse effects of INTENSIVE farming
by using GM crops and employing BIOLOGICAL control as alternatives to the
use of pesticides. Biological control is the reduction of a pest population by
the introduction of one of its natural ENEMIES.
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