Page 95 - Science Class 07

NETWORK OF TUBES the slice. Leave it for five minutes. You will
Plants have a well-developed network of tubes observe the vascular bundle of xylem and
present everywhere in plant’s body. These phloem arranged in ring.
tubes help in sending water and mineral salts Both the tubes, xylem and phloem are

to leaves and in sending prepared food to packed as a compact mass called vascular
different parts. These tubes are grouped into bundles.
xylem and pholem.
Xylem
The tube which carries water and minerals
from the roots to the leaves of the plant is
called xylem. These are made up of dead cells
and transport water and minerals salts only in

an upward direc on. The xylem ssue
transports water and minerals from the roots
to the leaves. Xylem ssue has tracheids and PROCESS OF TRANSPORTATOIN
vessel elements. Let’s see how transporta on system is carried
Phloem out by plants:
Tubes (sieve tubes) which transport sugar Transporta on of Water and Mineral Salts
made by photosynthesis from the leaves to
v Plant roots take in water and dissolved
growing area of the plant and to food storage
minerals from the soil through root hair.
areas are called phloem. The phloem is
Root hair takes in water through a combi-
responsible for the transloca on of the
na on of diffusion and osmosis.
nutrients like carbohydrates and amino acids
v Water entering root hair gradually flows
from the leaves to other areas of the plants.
further into the root from cell-to-cell and
Here, the flow is bidirec onal. It moves up and
eventually reaches the root xylem vessels.
down the stem. Phloem occupies the edge of
Water flows into root xylem vessels with
the vascular bundle. Food movement in the
phloem occurs due to the pressure flow sufficient force to push it up into the stem
xylem.
mechanism. The differences in the osmo c
pressure help in the movement of food from v The stem xylem tubes are connected to the
the area of high concentra on to areas of low leaves of the plant forming a con nuous
concentra on. pipe of cells. In the leaves, this water is
used for photosynthesis.

water and minerals no end walls between cells one-way only outer cells are not living

Phloem

To observe xylem and phloem.

Take a so stem of a herb plant and cut a
thin slice of it. Add a few drop of safranin to
Xylem Tube
Science-7 95