characteristics of life all organisms have many features or characteristics in common
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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
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Vertebrates Invertebrates
Reptiles Insects
Arachnids
Fish
Birds
Worms
The Diversity of Plants
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Algae
Ferns
Moss
Conifers
Flowering Plants
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
METABOLISMMetabolism is the chemical reactions that occur in
the cells of living organisms
These reactions are responsible for the process of • Growth• Repair• Responsiveness• Reproduction
All living things metabolise10
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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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?
• 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
• 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
• 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?
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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
Growth and Development
• 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.
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