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

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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

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

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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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?

• 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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END

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