www.BioTopics.co.uk
Feedback Next Unit?

THE 7 CHARACTERISTIC PROCESSES OF LIFE


Biology is the study of life and all living organisms, so we must be clear about the difference between living and non living "things".
All living organisms have the potential to carry out 7 basic processes, i.e. special actions which may be called the characteristics of life.
These processes are universal, but when you consider the fine details you will see that they are carried out in somewhat different ways by animals and plants, although Biologists now classify living organisms into more than 2 kingdoms.

Biology may be broken down into the study of animals - Zoology - and the study of plants - Botany. However, all living organisms depend on one another, and that definitely includes Man as well, so Biology deserves to be studied as an all-embracing subject.

Try to find some other branches of Biology which can be studied in their own right, (and which offer possibilities of further study and employment)
e.g. physiology - the study of the internal processes and functioning of organisms
microbiology - the study of micro-organisms, i.e. "small" organisms like bacteria, fungi, algae (& viruses too).
> nutrition, genetics, ecology
> anatomy, human biology (explained)


The 7 Characteristic Processes of Life

PROCESS NAME
and DEFINITION
PROCESS DETAILS
in ANIMALS
PROCESS DETAILS
in GREEN PLANTS
1
MOVEMENT
the ability to move
n.b. Locomotion -
movement (of the whole organism) from place to place
- is considered to be an animal characteristic,
but simple "plants" may swim.
1A
Humans usually use muscles to move by walking or running.
Other animals may move by other methods such as:
hopping, crawling, swimming or flying.

Advanced animals usually (but not always) move faster, so they need more energy.

Even so called sedentary animals tend to move or drift in their larval stages to ensure dispersal to new habitats.
1B
Movement in plants is by growth.
Parts of higher plants - branches, flowers, roots - move as they grow, so the process is usually quite slow.
Some parts of plants, e.g. flowers, leaves - may open or close depending on the time of day.
Dispersal of seeds results in new plants
being spread to new areas away from their parents.
Some plants (exceptions to the rule)
can move (parts) quite fast, e.g. the Venus fly trap, and the sensitive plant Mimosa.
2
SENSITIVITY
(IRRITABILITY)
the ability to respond
to stimuli from the
surroundings -
changes in the
environment - using
"senses"
2A
Humans are said to have 5 senses:
sight, hearing, smell, taste, touch.
These perceptions result from
information from the corresponding
sense organs:
eyes, ears, nose, taste buds, skin.
Insect antennae can detect these and
other stimuli.
Higher animals have more complex
nervous systems.
2B
Plants react to fewer stimuli: gravity,
water and light
are the main ones.
The (growth) response is slower, and
often directed either towards or away
from the stimulus.
Some climbing plants, e.g. beans, also
react to the touch of a possible support,
such as the bean pole.
3
GROWTH
increase in (size or)
number of cells
(presumably in order to be more efficient)
3A
Like most animals, humans stop
growing
at adult size
3B
In general, plants continue to grow
throughout their lifetime.
4
NUTRITION
(FEEDING)
obtaining and using
food -
either to be built up
(assimilated) for
growth and repair,
or used as a fuel - see
later.
n.b. Digestion itself is
not a specific
characteristic
process of living
organisms, or even of
all animals.
4A
Animals either eat plants directly, or
eat other animals .... which themselves
eat plants
This is because animals cannot
"make" (chemically synthesise) their
own food.
Complex substances of plant origin are
broken down into simpler ones, and
their energy is released as a separate
process.
4B
Green plants are able to synthesise their
own food by the process of
photosynthesis.
Simple (inorganic) substances are built
up into complex (organic) ones - the
same as those also used as foods by
animals.
Mineral salts are also nutrients for
plants, but not foods providing energy
5
RESPIRATION
(getting energy from
food - this occurs
inside the cells)
n.b. Energy is not
"made" - it is merely
released from the
organic molecules, by
oxidation - usually
needing oxygen .
Not the same as
breathing, which is
only done by some
active animals.
5A
More active animals need more
energy, so higher animals like Man
have a respiratory system with a
specialised gas exchange surface, and
also a circulatory system to transport
oxygen around the body.
Breathing is a pumping action in order
to get more oxygen, but not all animals
perform it.
5B
Plants are less active, so they need less
energy, and so they can devote more
resources to growth, etc.
Photosynthesis seems to reverse the
respiration process, but it is an extra
process only found in green plants.
(Aerobic) Respiration is exactly the same process in animals and plants!
"food" + oxygen ---------> "waste" substances + energy
(e.g. glucose).... ---------> (e.g. water & carbon dioxide)
[n.b. energy is not a substance like the others]
6
EXCRETION
removal of waste
produced inside cells -
not to be confused
with removal of
undigested food
6A
Main excretory organs:
lungs, kidneys, skin (sweat glands)
6B
Plants may store their waste in old
leaves.

Oxygen is a waste product of plants!
7
REPRODUCTION
production of new
individuals
(offspring)
n.b. Sexual
reproduction is not
confined to animals
7A
Humans give birth to babies, but other animals may have their young via an egg. Offspring may not initially resemble parents but eventually grow to do so.
In sexual reproduction, only one sex (female) produces offspring.
Some animals carry out asexual reproduction, e.g. aphids, and Hydra
7B
Flowering plants reproduce sexually
to produce fruits containing seeds
which germinate to give rise to new
plants.
Plants may also produce asexual
structures to quickly make more
individuals which are direct copies of
the original.



This topic has connections with other units on:-
CELL DIVISION and CHROMOSOMES
(ANIMAL &) HUMAN NUTRITION
DIGESTION & ASSOCIATED PROCESSES
THE DIGESTIVE SYSTEM
PLANT NUTRITION
THE STRUCTURE OF THE LEAF
THE RESPIRATION PROCESS
THE HUMAN RESPIRATORY SYSTEM
HOMEOSTASIS, EXCRETION AND THE KIDNEYS
SENSES, SENSITIVITY, STIMULI AND SKIN
THE EYE AND VISION
THE EAR
THE BRAIN AND NERVOUS SYSTEM
THE HUMAN REPRODUCTIVE SYSTEM
PREGNANCY AND BIRTH


Return to the contents page? Practical activity to support topic Background to topic Another look? Back to the BioTopics index page? Next Unit?