- Roots:
hold the plants in the ground and give them water and mineral salts.
- Stem:
Give the plants shape.
- Leaves:
make their food.
4.3.- Groups of plants
There are two groups of plants:
Plants without flowers. These plants do not have flowers or seeds. They
reproduce
with spores.
Plants
with flowers. These plants reproduce with seeds.
According to their size, We can classify plants with flowers into three groups: trees,
shrubs and grasses.
SIZE
STEM
BRANCHES
AGE
TREES
They are
Large
They have
Woody, hard
stems called trunks
They come from the trunk.
They live many years.
SHRUBS
They are
Medium-sized
They have woody, soft and thin trunks
The branches come from the ground.
They live many years.
GRASSES
They are
Small.
They have non-woody stems that are soft and
flexible stem.
They have no branches or leaves.
They live a few months.
4.4.-
Plant nutrition.
Plants have three stages in their nutrition:
1.Getting
nutrients:
Plants get Carbon dioxide from the air through their leaves.
Plants get water and mineral salts from the soil through their roots.
This mixture is called Xylem sap.
2. Making food:
Photosynthesis is the process of plants making their own food and
producingoxygen. During this
process, the green substance (called chlorophyll) in leaves catches the
sunlight.
The
xylem sap (water + mineral salts) goes up the stem to the leaves through tubes called xylem vessels.
3.
Transporting food:
The leaves transport the phloem sap throughout the
plants: roots, stem, flowers and other leaves.
4.5.-
Plants reproduction.
-Plants with flowers have reproductive
organs:
·Stamens are the male reproductive
orgnas. They have round sacs that produce pollen.
·Pistill
is the female reproductive organ. It has a bottle shape with ovules inside.
·Corolla. It is made up of a group of
coloured sepals and petals.
·Calyx: It is a group of small leaves
called sepals.
Plants carry out reproduction to make
new plants that are similar. Stages in the reproduction:
1.Pollination: Grains of pollen are transported from the stamens to the pistil.
2.
Fertilisation: In the pistil, the grain of pollen joins an ovule.
3.
Fruit is a fertilized ovule and it has seeds inside.
4.
Germination: The seeds grow into a new plant.
-Plants without flowers reproduce by spores.
Spores are special cells that germinate and grow into a new plant.