Page 96 - Science Class 07

v Minerals are present in the form of
dissolved salts in the soil. But, root hair
cannot absorb mineral salts just by the
Many aqua c plants do not have roots or
process of osmosis or difussion because,
poorly-developed roots because plenty of
unlike water molecules, the molecules of
water is present around them. They can get
mineral salts are less in number outside
water through stems.
the root hair as compared to that inside
the root hair. Therefore, the root hair
Transporta on of Food
absorbs minerals from the soil by another
v The carbohydrates manufactured in the
process called ac ve transport.
leaves of plants are distributed to different
v The salts are more highly concentrated in
parts of the plants through phloem.
the sap within the root hair than in the soil
v The movement of carbohydrate to different
solu on. Therefore, water passes from the
parts of the plants is called transloca on.
soil into the cell by the process of osmosis.
There is also a network of phloem tubes spread
Dissolved minerals, in the form of ions, also
throughout the plant’s body. These tubes are
pass from the soil solu on, through the cell
also called sieve tubes. Through these tubes
membranes and into the cells.
carbohydrates are distributed.
v When water and mineral salts enter the
cells they swell and become turgid. In this
way, the concentra on of the lower cell is
higher than it is in the cells next in line. 1. What is diffusion?
Thus, water and mineral salts move
2. How do plants send prepared food to
upward to the leaves. different parts of their body?

3. How water and mineral salts are
transported in plants?
To show xylem transports water to the 4. How carbohydrates are distributed in
leaves. plants?

Take a plant having so stem and put the
TRANSPIRATION
roots of the plant in a beaker containing red
colour water. Transpira on is the process in which plants

Leave it undisturbed for an hour. You will release the water inside them in the form of
observe that the colour of the stem of the moisture or water vapour. Parts of plants like
plant has become red. stems, small pores on leaves, flowers evaporate
the water to the atmosphere. Basically,
It shows that xylem of the plant helps in transpira on is the process in which water is
transporta on of water in the plants.
evaporated in the atmosphere from plant
leaves and other parts. Some amount of water
is consumed by roots and rest is evaporated in
the atmosphere.

96 Science-7