Exercises
SECTIONI
C. Choose the correct option.
1. Structures in roof that help to absorb water are
a roof contex
broot hair
o epidermis
d. cuticle
2 The pressure created which pushes water from roof cells to xylem
awo pressure
broot pressure
cofusion pressure
d. none of these
3. Tonspiration is me
a loss of woter by evaporation from aerial pons of plant
loss of excess water from aerial parts of plants
crise in woter from roots to leaves
a loss of minerals from oenol parts of plants
4 The ole of monspiration increases when
o the day is not ono numid b sol is dry
ct is ook
o the day is hot and windy
5 Which of the following processes requires energy?
c. Active Tonsport
b Difusion
c Osmosis
d. Al of these
D. Write True or False. Correct the false statements by changing the first or the last words)
1. Tonspiron pulloon couse ascent of sop
2 Tonsoon of food molerols is known as transiooonon
3. The process which equires a sempermeable membrone is diffusion
4. Nitrogen is o moronutrient
5 The role of nonspiration increases with an increase in temperature
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Answers
Answer:
1)While plants can absorb water from many sources the best place for this is the root system which is in contact with the soil where most of the water is found. The root system is usually extensive and has root hairs which help increase the surface area for water absorption. Water enters the root hair cells and then moves from cell to cell till it reaches the root cortex it goes on to the xylem vessels to be transported to the leaves.
So, the correct option is 'Root hair'.
2)The physiology of water uptake and transport is not so complex. The main driving force of water uptake and transport into a plant is transpiration of water from stomata present in the leaves.
Transpiration is the process of water evaporation through specialized openings in the leaves, called stomata. The evaporation creates a negative water vapor pressure, developed in the surrounding cells of the leaf.
Once this happens, water is pulled into the leaf from the vascular tissue, the xylem, to replace the water that has transpired from the leaf.
This pulling of water, or tension, that occurs in the xylem of the leaf, will extend all the way down through the rest of the xylem column of the tree and into the xylem of the roots due to the cohesive forces holding together the water molecules along the sides of the xylem tubing. (Remember, the xylem is a continuous water column that extends from the leaf to the roots.) Finally, the negative water pressure that occurs in the roots will result in an increase of water uptake from the soil.
Now if transpiration from the leaf decreases, as usually occurs at night or during cloudy weather, the drop in water pressure in the leaf will not be as great, and so there will be a lower demand for water (less tension) placed on the xylem.
The loss of water from a leaf (negative water pressure, or a vacuum) is comparable to placing suction to the end of a straw. If the vacuum or suction thus created is great enough, water will rise up through the straw. If you had a very large diameter straw, you would need more suction to lift the water.
Likewise, if you had a very narrow straw, less suction would be required. This correlation occurs as a result of the cohesive nature of water along the sides of the straw (the sides of the xylem).
Because of the narrow diameter of the xylem tubing, the degree of water tension, (vacuum) required to drive water up through the xylem can be easily attained through normal transpiration rates that often occur in leaves.
Answer:
1- root hair
2-none of the above
3-loss of woter by evaporation from aerial pons of plant
4-the day is hot and windy
5-Difusion
1-false
2-false
3-true
4-false
5- true
Explanation:
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