Page 104 - Science Class 06

prepare food for the plants. The thick skin 2. Give two examples of plants that have
of the stem also protects the plant from
water loss as cactus generally grow in
deserts. These stems also bear thorns
which protect the plants from grazing
animals.
Func ons of Stem
v It supports and holds leaves, flowers,
and fruits.
v The stem support the leaves to provide
water and minerals that can be
converted into usable products by
photosynthesis and thus transport it to
the leaves and the other parts.
v The xylem and phloem present in the
vascular bundles of stems conduct
water and minerals across the plant.
v Stems bear flowers and fruits in a
posi on that facilitates the processes of
pollina on, fer lisa on and dispersion
of seeds.
v Some stems undergo modifica on to store
food and water. For example, succulents.
v Some stems are modified to carry out
vegeta ve propaga on which is a form
of asexual reproduc on seen in plants.
The underground stems look like roots.
These roots are called Rhizomes. This
word comes from a Greek word meaning
“mass of roots”. Ginger, turmeric, potato
are rhizomes.
1. What are the func ons of a stem?
104
modified stems to store food?
3. How do tendrils give addi onal support
to plants?
4. Why do the desert plants have stem
with thick skin?
THE LEAF
The importance of green leaves is easily
overlooked. Besides telling us about the
health and nourishment of our crop, green
leaves are actually the food factory for the
plant. In the green leaf, sugars and starches
are made for plant growth and for storage
in the roots and the fruits. This is no
common task. In fact, the green leaf is the
only living thing in the world that can
transform the sunlight into food energy!
Photosynthesis, the process by which the
leaves perform this task, is very complicated
and s ll not completely understood by the
experts.
To make starches and sugars, the leaves
take in certain elements from the air and
combine them with water and nutrients
brought up by the roots from the soil.
Sunlight is the energy used to perform the
task. This process can only take place in the
green parts of the plant. When yellow or
off-coloured leaves are no ced on the crop,
the farmer knows that such plants are not
producing food. Off-coloured leaves indicate
Sunlight
Oxygen Water
Science-6