UNIT 5: ECOSYSTEMS

1.1 Ecosystems

Living things live in places with different characteristics. They are part of an ecosystem because they depend on one another to live.  A forest, a desert or a river are different ecosystems.

Ecosystems have three important elements:

• The habitat is the place where the living things of an ecosystem live. The characteristics of the habitat decide what ecosystems exist there.

• The living things that live in an ecosystem.

• The relationships that exist between living things and their habitat.

All ecosystems need a source of energy that comes from the Sun.

1.2 The habitat

The characteristics of a habitat, like its water, terrain, humidity or sunlight, decide what kind of ecosystem it is and the kind of living things that can live there.  There are two large groups of ecosystems based on land or water:

·         Aquatic ecosystems.  Water is the main element of these ecosystems.  The water can be freshwater or saltwater.  In these ecosystems, important characteristics are the water’s temperature, its transparency or how much oxygen it has.

·         Terrestrial ecosystems. Land is the main element of these ecosystems.  Important characteristics are how many hours of sunlight the terrain gets, how high it is above sea level or how much precipitation it gets.

1.3 Living things

An ecosystem can have living things from many different species.  We can group them in different ways:

·         Population.  This is a group of living things of the same pecies that live in an ecosystem.

·         Community.  This is a group of different populations living together in an ecosystem.

UNIT 4: PLANTS

   1    Plants

Characteristics of plants 

The living things in the plant kingdom have these characteristics:

·         They are multicellular organisms.

·         They cannot move around.

·         They make their own food from the nutrients they get from the air, water, soil and sunlight.

·         They have three parts: roots, stem and leaves.  Their roots hold them in the ground and give them water and mineral salts.  Their stems give them shape and their leaves make their food.

·         Almost all plants live on land.  Some are aquatic.

Plants are classified into two groups:  plants with flowers and plants without flowers.

Groups of plants

There are two groups of plants:

• Plants with flowers.  These plants reproduce with seeds.  Some seeds come from a fruit and other seeds come from cones.

We can classify these plants into three groups: trees, shrubs and grasses.

• Plants without flowers.  These plants do not have flowers or seeds.  They reproduce with spores. 

Trees, shrubs and grasses 

We classify plants with flowers according to their size:

• Trees.  They are very large.  They have woody stems called trunks.  These trunks have branches.  Trees grow slowly and live many years.
• Shrubs.   They are medium-sized.  They have woody stems, but they do not have trunks because they are softer and thinner.  Their branches come from the ground.  Some grow very quickly and others grow slowly.  They also live many years.
• Grasses.  They are smaller.  They have non-woody stems that are soft and flexible.  Most grow very quickly, but they only live a few months.
  
  
  Activities:

1.- Answer these questions:

What are the three parts of plants? 

What do each of the three parts do?

Name and describe the two groups of plants.

How do we classify plants with flowers?

What are trunks?

2.- Complete the sentences using:

Grasses

Shrubs

Trees

 

_______________________________are very large and have woody stems called trunks.

______________________________are medium sized and have woody stems but no trunks.

____________________________ are small and have non-woody stems that are soft and flexible.

 

UNIT 3: INVERTEBRATES

3. OTHER GROUPS OF INVERTEBRATES

There are other groups of invertebrates with very simple structures. These invertebrates are worms, porifera, echinoderms, jellyfish, anemones and corals.

Worms

Their bodies are long and soft and are usually ringed

Some are terrestial and others are aquatic.

Some are parasites

Worms are invertebrates with long, soft bodies. They can live on land or in the water. Some are parasites.

Porifera

They have soft, irregular bodies with lots of pores, like sponges.

They eat the substances that they filter through their pores.

They are aquatic and most live on the rocks in the sea.

Porifera have soft, irregular bodies with pores. They are aquatic.

Echinoderms

Their bodies have a radial symmetry.

Hard pieces cover and protect their bodies. Some have spiny bodies, like the sea urchin.

They are aquatic animals that move sloyly along the sea floor.

Echinoderms have bodies with a radial symmetry that have hard pieces to protect them. They live in the sea.

Jellyfish, anemones and corals

They have soft bodies, although corals have hard covering.

They are aquatic and most live in warm water. Corals and anemones live on rocks. Jellyfish float in the sea.

Jellyfish, anemones and corals are aquatic. They have soft bodies although corals have hard covering.

Activities

1.- Match the group of invertebrates with their characteristics

                                  Worms                        They have soft bodies with pores

                                Poriferia                        Hard pieces cover thir bodies

                         Echinoderms                        Some live on the rocks and others float in the sea

Jellyfish, anemones and corals                        Some are parasites

2.- Fill in the gap

Porifera have ______________, ___________bodies with lots of __________, like sponges.

They eat the substances that they _________ through their pores.

They are _____________ and most live on the rocks in the sea.