Download Biological Responses - NCEA Level 3 Biology

Biological
Responses
Response of Organisms to the
Abiotic World
• Biological Timing Responses
All organisms, except those living in
deep caves or in the depths of the
ocean, respond to night and day, the
seasons, the tides and even the
phases of the moon.
These organisms can have:
Annual cycles – yearly changes of the seasons
Daily cycles – night and day
Lunar – monthly cycles often related to the
moon
Tidal – related to the ebb and flow of the tides.
Biological Timing Responses
Cont
• It is advantageous to an organism to
synchronise its activities with the rhythms in
its environment.
• There are 3 basic ways of synchronising the
physiology and behaviour of organisms to
these cycles.
• An exogenous Rhythm
this is a direct response to an
environmental response, i.e. the rhythm is
controlled by the external environmental
stimuli detected by an organism (the surge
in plant growth in the wet season)
Biological Timing Responses
Cont
• Endogenous Rhythm
an internal biological clock that
programs the organism’s behaviour
to synchronise with the external
environment.
• A combination of exogenous and
endogenous rhythms.
How do we know some rhythms
are Endogenous
• They continue in a constant
environment.
• These are said to be free-running.
• The rhythm has a frequency that is not
the same as the period of an external
environmental factor.
e.g.the human circadian rhythm is not
24 hrs but 24hrs and 42 mins
How do we know some rhythms
are Endogenous?
• The rhythm may persist when the
organism is moved from one part of
the world to another.
e.g. periwinkles move up and down the
rock face in response to the tides. If
placed in a tank miles away from the
sea, they still move up and down the
tank in the same rhythm as the ocean
tides.
Find these definitions…
Biological clock
Period of rhythm
Phase shift
Free running
period
Entrainment
Zeitgeber
Circa
Photoperiod
Anthropomorphism
Ethology
Stimulus
Receptor
Effector
Biotic Factors
• Coping with the physical factors in the
environment is only one aspect of
survival.
• Equally important are:
– For animals – obtaining food
– For all organisms – avoiding being
used as food by other organisms
eg predators and parasites.
Biotic Factors
• Competition –
– this exists when demand for a
resource exceeds its supply.
– This may be interspecific – between
species
– Or intraspecific – within a species.
Biotic Factors
• Exploitation –
one organism benefits at the expense
of another which is harmed to a
certain degree. This includes
predation, grazing and parasitism.
• Cooperation –
both organisms benefit, could be
mutualism i.e. between species or
within a species, as in reproduction in
many animals.
Biotic Factors
• Commensalism –
the members of one species benefits
and the other is not affected in any
way.
e.g. epiphytes (perching plants), these
take no nutrients from the tree on
which they perch, they are there purely
to gain light
Biotic Factors
• Mutualism –
both organisms benefit from their
association with each other.
• Antibiosis –
one member of the partnership is
inhibited and the other is unaffected.
e.g. fungi give out a substance which
inhibits bacterial growth.
Biotic Factors
• Succession –
the replacement of one species by
another over time.
• Stratification –
vertical relationships in space with
other organisms
e.g. layers of animals as you go down
the depth of the ocean to the bottom of
the sea.
Summary of Interspecific
Relationships
• Ref pg 9 Designs of Life