Science 4º

Plants are all around us. They are living things because they do the three life processes: nutrition,

interaction and reproduction. Plants are very important for us because they give us they oxygen that

we need to live and clean the enviroment of pollution.

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Plants

There are many different types of plants

which we can classify in different ways.

Grasses Bushes Trees

They have a soft

stem and they

are thin, flexible

and short.

They have a

thick and hard

stem with low

branches.

They have one thick

and hard stem called

trunk. They are tall

and with high

branches.

Trees can be differents. There are deciduous trees (they change their

leaves in autumm) and evergreen trees (they change their leaves all year

round).

Science 4º

We can also classify plants by how they reproduce. There are flowering plants and

non-flowering plants.

Plants

There are two subgroups:

Angiosperms: They produce big and colorful flowers which will turn

into fruit with seeds inside. For example: roses, apple trees or blackberry

bushes.

Gymnosperms: They produce small flowers and don’t produce fruit.

Their seeds develop inside cones. For example: evergreen trees like the

pine.

In this group we find mosses and ferns. They don’t produce seeds, they

produce tiny spores which they release into the air.

Flowering plants

Non-flowering plants

Leaves

Branch

Trunk

Soil

Roots

Parts of

a tree

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Science 4º

How plants make their own food? They make their food by photosynthesis and they need:

Water + minerals + light and energy from the Sun + carbon dioxide

Plants

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During the process of photoshyntesis,

plants release oxygen into the air.

PHOTOSYNTHESISEnergy and light

from the Sun

Carbon dioxide

WaterMinerals

The roots absorb water and

minerals from the soil.

The water and minerals travel

up the stem to the leaves.

The leaves make the food in this process

called photosynthesis where the plant

absorbs carbon dioxide through their leaves.

The carbon dioxide combines with water,

minerals and sunlight to make food.

Remember this ecuation!

Water + minerals + light and energy from the Sun + carbon dioxide = Food + oxygen

Oxygen

Science 4º

Plants, as living things, need to breathe. During their breathing process plants absorb

oxygen and expulses carbon dioxide but, as you know, during the day they do the

photosynthesis, so they produce oxygen too. But only during the day!

Plants

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respiration

Photosynthesis

Oxygen

Carbon dioxide

Respiration

Carbon dioxide

Oxygen

Respiration

Oxygen

Carbon dioxide

Carbon dioxide

Oxygen

Carbon dioxide

Oxygen

During the day At nigth

Science 4º

As you know, plants are classified as flowering plants and non-flowering plants.

In this part, we going to learn how flowering plants reproduce.

Plants

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Flowering plants use their flowers to reproduce because inside the flowers are the reproductive organs.

These reproductive organs make the seeds that grow into the new plants.

Animal pollination Wind pollination

Stigma

Stamens

Petals

Sepals

Ovary

They produce

pollen.

They recive the pollen

from other flower to

the ovary.

It grows into a fruit

which has seeds inside.

They are small

green leaves that

protect the flower

before it opens.

They can be many

different colours and

attract insects to the

flower.

Insects and birds that feed with nectar

transfer the pollen of the flower from the

stamen to the stigma of another plant.

It is when wind blows the pollen from

one plant to another.

In this page, you can see how a flowering plan reproduces.

Science 4ºPlants

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Pollen from other flower lands

on the stigma and travels down.

A seed develops inside the

ovary.

The ovary takes the form of

a fruit and the petals fall.

The fruit grows and falls. When

it is on the ground, it opens and

lets the seeds go out.

The seed germinates and

a new plant grows.

The new plant produces

flowers and the cycle starts

again.

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