UNIT 4 –
LIFE ON EARTH
A PLANET FULL OF
LIFE
Why is there life
on Earth?
* It is a temperate
planet: not too hot and not too cold.
* It has a lot of water.
* The atmosphere
protects and maintains living things.
All living things
form the biosphere.
The habitat is
the place where living things live. There are water and land habitats.
Water habitats
- Oceans and seas: living things are all adapted to salt
water.
- Rivers and lakes: living things are all adapted to
fresh water.
Some land habitats
- Deserts: are very dry.
- Jungles: are warm and very humid.
- Polar regions: are very cold.
- Mountains: are cold and there is little air.
- Savannas: are warm and dry.
- Caves: are dark and underground.
.
LIVING THINGS
Living things and
non-living things
On Earth there are living things like plants and
animals.
Living things are born, grow, reproduce and die. Examples: animals and plants.
Non-living things: are
not born, they do not eat, grow, reproduce or die. Examples: cars, rocks.
There are natural
non-living things like the sun, rocks and man-made
non-living things like cars, a book.
The characteristics
of living things
All living things
have three vital functions: nutrition,
reproduction and interaction.
- Nutrition:
to take substances to obtain energy and grow. Then they excrete the waste
products.
- Reproduction:
living things produce babies with the same characteristics. They reproduce in
different ways.
- Interaction:
living things interact with others.
PLANTS, ANIMALS AND
OTHER LIVING THINGS
What kinds of
living things are there?
We classify
living things in groups depending on their common characteristics.
Plants and animals
Most living things are divided into two big groups: plants and animals. All plants and animals have characteristics in common.
Plants
- They make their own food.
- They usually have roots, stems and leaves.
- They do not have senses.
- They are usually green.
- They can react to their surroundings but they don’t
move.
- They usually reproduce by seeds.
Animals
- They obtain their food from other living things.
- They have senses.
- They react to their surroundings and can usually move.
- They reproduce from eggs or in their mother’s body.
Other living things
Apart from animals and plants there are many other
kinds of living things like bacteria, algae and fungi.
- Bacteria: are microscopic. Some cause illnesses and
others live inside us and help.
- Algae are similar to plants, but they don’t have
roots, stems or leaves. They are usually very small, but some are very big.
- Fungi: they feed on other living things. They don’t
have senses or move from one place to another.
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