Download Science 5th primary 1st term unite 2 lesson 2 From your previous

Science 5th primary 1st term unite 2 lesson 2
Absorption and transmission of water
And mineral salts in plants
From your previous studies
We learned that green plants depend on raw materials to
form their food by photosynthesis process:
-
to do photosynthesis process the green plants take :
1 – Carbon dioxide CO2 from air
2 – water and mineral salts from soil.
** Green plants use the previous materials in presence of light
to make their food.
**
-
Green plants also need very little amounts of elements such as:
phosphorus
magnesium
calcium
nitrogen
zinc
other elements.
** Green plants absorb water and minerals salts from soil though root hairs that
present in roots.
Activity >>> to show the structure of a plant root.
Materials
- planter containing an important plant.
- Ready made slide of cross section in a plant root.
- Microscope.
Steps:
1 – remove the plant from the planter.
2 – examine the roots of the plant.
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Ms. Marim
Science 5th primary 1st term unite 2 lesson 2
Observation:
Roots are branched and extended through the soil particles.
3 – examine the ready made slide of cross section in plant root by using microscope.
Observation:
A: the roots is composed of a number of layers which are:
1 – Epidermis layer:
It is the external layer.
2 – Cortex layer:
It follows the epidermis layer.
The last row of cells in cortex layer is called
endodermis.
3 – Xylem (wood) layer:
It follows the cortex layer.
4 – Pith layer:
It is the last layer that follows the xylem
layer.
B: the root hairs:
Extend from the cells of epidermis ( external layer).
** from the previous activity we can conclude the functions of the plant root system.
Functions of root system
1 – fix the plant in the soil through root branches.
2 – it covers a lorge area of soil in order to:
a. search for water and mineral salts.
b. absorb and raise water and mineral salts to the plant.
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Ms. Marim
Science 5th primary 1st term unite 2 lesson 2
Structure of root hairs
1 – they extend from the root.
2 – they lined from the inside with a thin layer of cytoplasm.
3 – they have big vacuoles that contain salt solution.
Note

the age of root hairs doesn't exceed a few days.

Because the skin cells (epidermis) slough from time to time resistance of soil
particles during extending of the root.

So they are replaced by new ones continuously.
G.R
The age of the roots hair does not exceed a few days?
Because the skin cells slough from time to time.
The role of roots hair and their appropriateness for absorption of water and
mineral salts.
1 – they have thin membranes that allow penetration of water and salts through it.
2 – they have large number that increases the surface area for absorption.
3 – they secrete a sticky substance that helps the root to penetrate through soil particles.
4 – concentration of salt solution inside their vacuoles is higher than concentration in soil ,so
it helps in water transport form soil to inside of root hairs by Osmosis.
Osmosis:
It is the transmission of water molecules through semi-permeable membrane from
an area with high concentration of water to an area of low concentration of water.
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Ms. Marim
Science 5th primary 1st term unite 2 lesson 2
Notes
1 – the high concentration of salt solution means that it contains a small amount of
water, so this solution has low concentration of water.
2 – the low concentration of salt solution means that it contains a big amount of
water, so this solution has high concentration of water.
Activity >>> to show the rising of water and salts from root to other
parts of plant.
Materials:
-
test tube or beaker.
Small flowered plant with its root.
Cotton
Eosin solution
Metal stand.
Steps
1 – fill test tube with eosin
solution (red colored)
2 – submerge the root of
plant in the eosin solution
3 – plug the test tube mouth
with a piece of cotton and
leave the activity for several
hours.
4 – make a cross section in
the stem of this plant and
examine its internal parts
with a microscope or a
magnifying lens.
Figure
Observation
Roots , leaves and
petals of the flower
appear in red color.
The internal parts of
stem appear red in
color.
Conclusion :
Water and mineral salts (juice) rise from the root to the other parts of the plant.
Explanation:
1 – roots hairs absorb juice from soil, because salt concentration inside their vacuoles is
higher than salt concentration in soil.
2 – so, the juice flows from soil across the semi-permeable membranes of root hairs
by osmosis.
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Ms. Marim
Science 5th primary 1st term unite 2 lesson 2
3 – then , the juice moves through root cells till reach the endodermis which regulates passing
of water to the xylem (wood tissue).
4 – xylem tissue rises the juice to reach the stem and other parts of the plant.
Notes
1 – the cell membrane of root hairs also has the selective permeability property
which allows only some salts to pass through according to the plant's need.
2 – The previous process needs energy that obtained form respiration process.
Activity >>> to show the transpiration process in plant.
Materials:
- bell jar,
growing plant in planter ,
Steps
1 – cover the soil and planter
with a fabric coated with
Vaseline.
glass board , Vaseline , fabric.
Figure
Observation
2 – tie the fabric around the
base of the stem tightly to
prevent loss of water from
the soil and planter wall.
3 – put the planter under the
bell jar and over the glass
board.
4 – leave the plant for
several hours.
Water drops are
condensed on the inner
surface of the bell
jar.
Conclusion :
Plants do a process called transpiration through which excess water comes out from the green
parts of the plant.
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Ms. Marim
Science 5th primary 1st term unite 2 lesson 2
Transpiration process:
It is the losing of water in the form of water vapor from the leaves or from other
green parts to the surroundings through holes called stomata.
Stomata:
1 – stomata are widely spread on the lower surface of the plant
leaves.
2 – plant loses most of the water that reaches the leaves
through stomata.
3 – each stoma is surrounded by two guard cells.
Function of two guard cells
They change their shapes to control opening and closing the stoma.
Activity >>> to show water emergence from leaves during transpiration.
Steps
1 – bring a leafy potted
plant.
Figure
Observation
2 – put one of its leaves
inside a transparent sac
and close it tightly.
3 – leave the experiment
in sunlight for several
hours.
Drops of water are formed
inside the sac.
Conclusion :
The plant loses some of its water through holes in the plant leaves called stomata in a
process called transpiration.
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Ms. Marim
Science 5th primary 1st term unite 2 lesson 2
Notes
When a plant loses water by transpiration:
1 – a pressure is formed that raises water upwards to the plant top.
2 – this power is the result of transpirations process.
The following figure shows how are water and dissolved salts transported to
all parts of a plant.
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Ms. Marim
Science 5th primary 1st term unite 2 lesson 2
Questions on lesson:
Complete the following statements:
1 – plants use …………………… gas and absorb ……………… and …………………… from the soil in the
presence of …………………….. to do photosynthesis process.
2 – plants need a very little amount of ……………………. That are necessary for their life.
3 – plants do ……………………………….. process to make their own food.
4 – the outermost layer of a plant root is called ……………………………
5 – the inner most layer of a plant root is called …………………………..
6 - ………………………. System fixes the plant in the soil.
7 – roots hairs are lined from inside by a layer of …………………………
8 – roots hairs have a big ……………….. that contains ……………………. Solution.
9 - …………………….. tissue moves water upward to the stem.
10 –plants can get rid of excess water through ……………………………… process.
11 – the ………………………….. are small openings that are widely spread on the …………………… surface
of the leaves.
12 – the ……………………… process in the plant forms a pressure that raises water upwards.
Choose the correct answer:
1 – plants get mineral salts from the ……………………….
a. soil
b. air
c. photosynthesis
2 – the plant makes its own food through ……………………… process.
a. respiration
b. digestion
c. sensation
3 – plants absorb water by their ………………………
a. roots
b. root hairs
c. stem
4 – root hairs extend from cells of …………………… layer.
a. epidermis
b. cortex
c. endodermis
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d. sunlight.
d. photosynthesis.
d. leaves.
d. xylem.
Ms. Marim
Science 5th primary 1st term unite 2 lesson 2
5 – root hairs secrete a ……………………….. substance.
a. watery
b. light
c. thin
d. sticky.
6 – plant loses water in the form of water vapour in ……………………. Process.
a. photosynthesis
b. osmosis
c. voluntarily feature
d. respiration.
7 – transpiration is a bio-process where the plant is ……………………… water.
a. gaining
b. absorbing
c. losing
d. a
,
8 – plants get rid of excess water through the ……………………………
a. root hairs
b. soil
c. stomata
d. roots.
9 – stomata are widely spread on ……………………………….
a. stem
b. leaf upper surface.
C. leaf lower surface.
10 – water rises from root to stem through ………………………layer.
a. epidermis
b. endodermis
c. cortex
b
and
c
d. root.
d. wood.
11 – the energy needed for absorption of mineral salts comes from the process of……………..
a. transpiration
b. photosynthesis
c. osmosis
d. respiration.
Give reasons for :
1 – plants make photosynthesis process?
……………………………………………………………………………………………………………………………………………
2 – root hairs secrete a sticky substance?
…………………………………………………………………………………………………………………………………………..
3 – the age of root hairs does not exceed a few days?
…………………………………………………………………………………………………………………………………………….
4 – the two guard cells change their shape from time to time?
…………………………………………………………………………………………………………………………………………..
5 – each stoma is surrounded by two guard cells?
………………………………………………………………………………………………………………………………………….
What happens if :
1 – plant kept in dark for long period of time?
……………………………………………………………………………………………………………………………………………
2 – root hairs do not secrete a sticky substance?
………………………………………………………………………………………………………………………………………….
3 – there are no stomata in the plant leaves?
………………………………………………………………………………………………………………………………………….
‫ و الشكر هلل‬,,, ‫الحمد هلل‬
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Ms. Marim