Normally the blood that oozes from a wound clots in 3-6 minutes. But
in some people due to vitamin K deficiency it takes more time. Because
of genetic disorder the blood may not coagulate. This type of disorder is
called haemophilia. Haemophilia is common disorder in the children who
have born from marriages between very close relatives. Thalassemia an
inherited disorder is also related to blood. For more details see annexure
There is a vast transport system in continual supply of essential
nutrients and oxygen to perform metabolic activities, and to remove
excretory substances which are found in each cell of animal body.
Is there anything like that in plants which corresponds
to circulatory system?
In previous classes we studied about Van Helmont’s
experiments on plants, which get water that contain
minerals from soil through their roots. The water absorbed
by roots and food prepared by leaves are supplied to the
remaining parts of the plant by vascular bundles having
xylem and phloem.
In the root, the xylem tissue develops from periphery
to center, whereas in the stem it develops from center to
periphery in each vascular bundle.
How is water absorbed?
We know that roots absorb water with minerals from soil.
• What is the mechanism behind this?
• Are roots directly in contact with water?
• How is water absorbed?
Absorbing root hairs
To perform this activity, you need to germinate bajra or mustard seeds.
Examine some mustard seedlings which have been grown on wet filter
paper. Observe the mass of fine threads coming from the seed by hand
lens. These are roots. They have fine microscopic structures called root
hairs. These are root hairs through which water enters the plant. Gently
squash a portion of the root hair between slide and cover slip in a drop of
water and examine under a microscope. Note the thinness of the walls of
root hairs. It is not completely understood how the water enters the root
hairs and passes inwards from cell to cell until it gets into the xylem vessels
In previous classes we studied about Van Helmont’s
experiments on plants, which get water that contain
minerals from soil through their roots. The water absorbed
by roots and food prepared by leaves are supplied to the
remaining parts of the plant by vascular bundles having
xylem and phloem.