Transcript Y13 3.4 Plants and Animals

Y13 3.4 Plants and Animals
Part 1: The environment
The environment is the sum total of abiotic
and biotic factors of an area that influence
the lives of the organisms present.
Abiotic factors
Physical factors that can act as stimuli (most have a latin
prefix they are known by)
•
•
•
•
•
•
•
Light (photo)
Gravity (geo)
Temperature (thermo)
Water (hydro)
Current (rheo)
Chemicals (chemo)
Touch (thigmo)
•
•
•
•
•
Sound
Pressure
Wind
Substrate
fire
• Tolerance: most organisms try to keep
within a narrow range of physical factors in
order to stay in their ‘optimum range’ of
tolerance.
Biotic factors
• All relationships between members of the
same species (intraspecific) and members
of different species (interspecific).
Relationships can be harmful, beneficial or
neutral.
Response of organisms to the
environment
• The response of organisms to the above
environmental factors (abiotic and biotic) is
behaviour. If the behaviour is genetic (e.g.
born with it) then it is called innate.
Otherwise it is learned. Some behaviour
can be a mix of both.
• Behaviour consists of:
– Stimulus: a change in the environment that
causes a response in an organism.
– Receptor: any cell or group of cells that can
detect this change.
– Effector: a cell or group of cells that respond
to the change.
Behaviour operates on a feedback system –
hence why you can learn it!
Some more definitions you need:
• Ecosystem: all living things and physical
things in an area.
• Habitat: the place or environment in which
a specific organism lives.
• Limiting factor: any factor of the
environment that limits the activity of an
organism or population.
• Anthropomorphism: ascribing human
emotions to animals (DON’T DO IT).
• Ecological niche: an organisms way of life,
describes the opportunities provided by
the habitat and adaptations of the
organism to make the most of the
opportunities.
• Adaptations: are inherited and can be
structural, behavioural, physiological or life
history.
• Gause’s principle: this states that no two
species with identical ecological niches
can co-exist for long in the same place.
Biological Timing Responses
• Can be annual, daily or lunar and are
governed by internal clocks.
• Biological clock: internal timing system
that continues without external clues and
can control the organisms response.
• Period of the rhythm: time it takes to
complete one cycle of activity.
• Phase shift: when the start of the activity
period is changed.
• Free running period; when the biological clock is
running without any environmental clues.
• Entrainment: the resetting of the biological clock
on a regular basis, done by a zeitgeber.
• Zeitgeber: environmental agent that resets the
biological clock e.g. change in light etc.
• Circa: about, circadian = about a day.
• Photoperiod: response of organism to length of
day or night.
• Exogenous rhythm: one controlled by external
environmental stimuli detected by organism.
• Endogenous rhythm; one controlled by internal
clock.
E.g.
Biological orientation responses
• Tropism: growth towards or away from stimulus
coming from a set direction
• Taxes: movement of whole organism toward or
away from stimulus.
• Kinesis: non-directional response to stimulus
• Nastic movement: response to stimulus but
independent of stimulus direction.
• Homing: ability to find and return to a home site.
• Migration: annual mass movement of animals
between breeding and non-breeding areas.
Responses to Biotic factors
• Intraspecific
–
–
–
–
Competition
Reproduction
Aggressive interactions
Cooperative interactions
• Interspecific
–
–
–
–
–
–
–
Competition
Predator/prey
Plant/animal
Succession
Stratification
zonation
Animal/animal and plant/plant