Characteristics of Life
All organisms have many features or
characteristics in common
Learning Objectives
• Present an outline of the diversity of living things
• What defines a living thing?
• List the common features & behaviours identified as
living
• Define the terms
Metabolism
Continuity of life
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The Variety of Life
All living things are divided into two main
groups
Plants
Animals
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The Diversity of Animals
• There are more than a million different species of
animals on earth
• Scientists have organised all these animals
according to how they are related
• The animal kingdom is divided into groups called
classes for example
Reptiles
Birds Mammals
These all have similar features which distinguish them
from animals in other classes
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The Diversity of Animals
Vertebrates
Invertebrates
Worms
Fish
Insects
Reptiles
Birds
Arachnids
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The Diversity of Plants
Algae
Ferns
Moss
Conifers
Flowering Plants
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Learning check
What is meant by Diversity?
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What makes Plants & Animals ‘living’?
• Do they have common features?
• Do they have common behaviours?
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Common Characteristics
Living things:
• are highly organised
• are composed of tiny units called cells
• grow
• excrete
• move
• react to their surroundings
• feed
• reproduce
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Metabolism
METABOLISM
Metabolism is the chemical reactions that occur in
the cells of living organisms
These reactions are responsible for the process of
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Growth
•
Repair
•
Responsiveness
•
Reproduction
All living things metabolise
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There are 2 types of Metabolic
Reactions
Anabolic Reactions
These reactions use energy to join small molecules
together to form larger molecules
Example: Photosynthesis
Catabolic Reactions
These reactions use energy to break down large
molecules into smaller ones
Example: Respiration
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Continuity of Life
Continuity of life is the ability of an organism to
exist from generation to the next
You need reproduction and heredity to achieve
continuity
Genes are hereditary factors that are passed on
from one generation to the next during
reproduction
All living things reproduce
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Learning check
Explain Metabolism
Explain ‘Continuity of Life’
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Need to know
• Present an outline of the diversity of living things
• What defines a living thing?
• List the common features & behaviours identified as
living
• Define the terms
Metabolism
Continuity of life
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1.2.3. Characteristics of Life
Life describes an organic based object that
possesses the characteristics of
metabolism and continuity of life
Learning Objectives
Definition and identification of the "characteristics of life",
through fundamental principles and interactions of
Organisation, Nutrition, Excretion, Response and
Reproduction.
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How do we know
if something is alive?
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It has organization – cells, tissues, organs, etc.
It uses energy
Grows and develops
Excretes
Reproduces
Responds to the environment
Adapts to the environment
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Organisation
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Unicellular or multicellular
Specialized structures
Cell is the basic unit of structure and function
If cell structure is damaged its function is also affected
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Levels of organisation
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Cell
Tissue
Organ
Organ system
Organism
Population
Community
Ecosystem
Biosphere
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Energy
• All energy for living things can be traced back to the
sun (primary source of energy)
• Organisms use light energy to see (vision), to make
food (photosynthesis), for warmth (respiration)
• Plants use sunlight to make food (producers)
• Other organisms eat the plants to get energy
(consumers)
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Learning check
How do we know something is alive?
•It has organization –
cells, tissues, organs, etc.
•It uses energy
•Grows and develops
•Excretes
•Reproduces
•Responds to the
environment
•Adapts to the
environment
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Growth and Development
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Growth – increase in size
Development – change in form or shape
Amount of growth varies in different organisms
Nutrition maintains the organisation and growth of
living organisms
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Nutrition
This is the process involved in the making and
receiving or the absorption and utilisation of food
(energy and materials) from the environment
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Sources of Nutrition
In Animals: feed on other organisms
In Plants: make food by photosynthesis and
absorbing chemicals from the environment
Energy flow:
Sun  Plants Animals
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Excretion
• Excretion - is the elimination of the waste products
of metabolism from a cell, tissue or organ
• All living things must get rid of waste material – if it
was allowed to accumulate it would become toxic
to the organism
• A balance must be maintained between their
internal and external environments
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Methods of excretion
Various organised structures involved
In Animals: the urinary system, skin, lungs
In Plants: the stomata
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Learning check
• What is meant by nutrition?
• This is the process involved in the making and
receiving or the absorption and utilisation of food
(energy and materials) from the environment
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Response and Adaptation
• Response = reaction to a stimulus in environment
• Adaptation – plants and animals change in response
to long-term changes in the environment; these may
be passed on to future generations (Charles Darwin)
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Methods of response
• In Animals: organised structures respond to light,
sound, touch, etc.
• In Plants: growth towards or away from a stimulus
e.g. light, water, fertilisers, etc.
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Learning check
What is Excretion?
• It is the elimination of the waste products of
metabolism from a cell, tissue or organ
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Reproduction
• Life comes from life.
• Reproduction is the ability of an organism to
produce new individuals of its own kind and pass
on genetic information to the next generation.
• Necessary for the survival of the species
• Offspring can be the same as or different from
parent(s)
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Methods of reproduction
• Asexual: e.g. in bacteria and protista – binary
fission (simple division in two) – mitosis
• Sexual: e.g. in plants and animals – involves two
parents and the production of male and female
gametes
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Learning check
• What is the purpose of reproduction?
• To produce new individuals of its own kind and
pass on genetic information to the next
generation.
• Reproduction is necessary for the survival of a
species.
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Interactions between organisms
• There are relationships between organisms living in
same habitat
• Predator-prey
• Symbiosis (Mutualism & Commensalism)
• Parasitism
• A change in one type of organism can cause other
organisms to change
– Organisms that can’t adapt fast enough might become
extinct
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Summary
• One characteristic is not enough to qualify
something as being alive.
• Life involves an interaction between metabolism
and continuuity
• Metabolism requires an interaction of organisation,
nutrition, excretion and behaviour
• Continuity requires organisation, nutrition,
behaviour and reproduction
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Need to know
Definition and identification of the "characteristics of
life",
through fundamental principles and interactions of
organisation
nutrition, excretion, response and reproduction.
36
END
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