Tag: ascent of sap

Questions Related to ascent of sap

Water potential of root cells is higher than water potential of soil.

botany water absorption and ascent of sap in plants factors affecting the transport of water and minerals in plants ascent of sap long distance transport of water

  1. True

  2. False

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Correct Option: B
Explanation:

Water potential is the potential energy of water per unit volume taking the reference of pure water. Water potential of the soil is higher than the water potential of root cell.

So, the correct answer is 'False'.

Energy source responsible for upward flow of water is

botany water absorption and ascent of sap in plants factors affecting the transport of water and minerals in plants ascent of sap long distance transport of water

  1. ATP

  2. Sucrose

  3. Solar heat

  4. Sunlight 

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Correct Option: C
Explanation:

Energy source responsible for upward flow of water is solar heat. Due to increase in the solar heat the temperature increases. The rate of transpiration is high on a bright sunny day due to excessive heat produced by solar heat. The water is lost from guard cell which leads to decrease in the water potential of guard cell as compared to the surrounding cell. To stabilize the water potential in the guard cell water rushes from the neighboring cell which creates a cohesion pull in the xylem vessels to pull the water up to the guard cell. Thus, the rate of water absorption increases when the transpiration is high. 

So, the correct answer is option C.

Which of these is a factor not related to transpiration pull?

botany water absorption and ascent of sap in plants factors affecting the transport of water and minerals in plants ascent of sap long distance transport of water

  1. Capillarity

  2. Adhesion

  3. Cohesion

  4. Ascent of sap

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Correct Option: A
Explanation:
(A) Capillarity is the motion of the liquid in a narrow passage which travels only up to a certain point where it balances the force of gravity of the column.
(B) Adhesion is the force of attraction which leads to the attraction between water and xylem molecule necessary for transpiration pull.
(C) Cohesion is the phenomenon of attraction between similar molecules, which makes water molecule remain attracted to each other while being lifted up by transpiration pull. 
(D) The suction force which makes water to move in an upward direction is the ascent of sap caused by transpiration pull.
So, the answer is, "Capillarity".

Ability to rise in thin tubes and ability to resist pulling force are ................ and  .................. respectively 

botany water absorption and ascent of sap in plants factors affecting the transport of water and minerals in plants ascent of sap long distance transport of water

  1. Tensile strength and capillarity.

  2. Cohesion and adhesion

  3. Capillarity and tensile strength

  4. Adhesion and capillarity

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Correct Option: C
Explanation:

Capillarity is the ability of water to rise through thin tubes.

The tensile strength of a substance is how well it can resist external force and maintain it's properties.
Cohesion is the attraction of two same particles.
Adhesion is the attraction of two different particles. 
So the correct answer is 'Capillarity and tensile strength'.

Transpiration - cohesion tension theory operates through

botany water absorption and ascent of sap in plants factors affecting the transport of water and minerals in plants ascent of sap long distance transport of water

  1. Active absorption

  2. Passive absorption

  3. Active and Passive absorption

  4. Apoplastic movements

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Correct Option: B
Explanation:
(A) Active absorption is the absorption process when it is being driven by the force present in the root which occurs through osmosis or use of active transport to move molecules of solutes to change the water concentration gradient.
(B) The force for passive absorption originates in the aerial part of the plant due to loss of water in transpiration which causes upward motion and cohesion theory is a theory of intermolecular attraction that explains the process of upward flow of water through the xylem.
(D) Apoplastic movement is the movement of water through the apoplast between loosely packed cortical cell which occurs in the root.
So, the answer is, "Passive absorption".

Active absorption of water by roots from the soil is mainly affected by 

botany water absorption and ascent of sap in plants factors affecting the transport of water and minerals in plants ascent of sap long distance transport of water

  1. Tension in cell sap due to transpiration.

  2. Hydrophobic nature of root hair.

  3. Typical tissue organisation.

  4. Osmotic concentration of xylem sap.

Show answer
Correct Option: D
Explanation:

Active absorption is the movement of water molecule along the gradient with the use of energy.

Osmotic pressure is the movement of a solute particle from low concentration to high concentration through a semi-permeable membrane.
So, the water will move from a higher concentration to a lower concentration.

So, the correct option is 'Osmotic concentration of xylem sap'.

If a soft stemmed plant is cut horizontally near the base of its stem with a sharp blade on early morning of a humid day, drop of solution ooze through cut stem. This is due to

botany water absorption and ascent of sap in plants factors affecting the transport of water and minerals in plants ascent of sap long distance transport of water

  1. Guttation

  2. Bleeding

  3. Transpiration pull

  4. Root pressure

Show answer
Correct Option: D
Explanation:

If we cut a small soft-stemmed plant on a day, when there is plenty of atmospheric moisture, early in the morning we will soon see drops of solution ooze out of the cut stem; this comes out due to the positive root pressure. If we fix a rubber tube to the cut stem as a sleeve we can actually collect and measure the rate of exudation, and also determine the composition of the exudates. Root pressure is a positive pressure that develops in the xylem sap of the root of some plants. It is a manifestation of active water absorption. Root pressure is observed in certain seasons which favour optimum metabolic activity and reduce transpiration. It is more during rainy season in the tropical countries and during spring in temperate habitats. So, the correct answer is 'Root pressure'.

Read the passage and answer the following question.
Wet mounts of three living samples of Elodea cells are prepared for viewing under the light microscope. Each slide is mounted with a different solution and viewed after 5 minutes.
Sample A - Elodea + 5 drops of 10% $\displaystyle NaCl$
Sample B - Elodea + 5 drops of isotonic saline
Sample C - Elodea + 5 drops of distilled water
Which of the following structure would be visible in sample A that was not visible prior to exposure to the 10% of $\displaystyle NaCl$?

botany water absorption and ascent of sap in plants factors affecting the transport of water and minerals in plants ascent of sap long distance transport of water

  1. Nucleus

  2. Plasma membrane

  3. Mitochondria

  4. Golgi body

  5. Chloroplasts

Show answer
Correct Option: B
Explanation:

In the presence of NaCl in the environment causes exosmosis and removes water from the cell. Once the water leaves the elodea cell, the membrane collapses into the center of the cell with the other remaining organelles. At this point, the plasma membrane is clearly visible.

Therefore, the correct answer is option B.

Osmotic theory of active water absorption was given by

botany water absorption and ascent of sap in plants factors affecting the transport of water and minerals in plants ascent of sap long distance transport of water

  1. Keller

  2. Bennet-Clark et al

  3. Atkins

  4. Kramer

Show answer
Correct Option: C
Explanation:

Water absorption takes place through root. There are two theories to explain the mechanism of water absorption. One is passive absorption and the other is active absorption. Osmotic theory of active water absorption was given by Atkins and Priestley. According to this theory, water is absorbed due to osmotic difference between soil water and tonoplasm. Water moves from soil to root xylem along the increasing gradient of suction pressure.

Thus, the correct answer is option C.

Wall of xylem vessels are made up of lignocellulose has a strong affinity for water molecules.

botany water absorption and ascent of sap in plants factors affecting the transport of water and minerals in plants ascent of sap long distance transport of water

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

Xylem vessels are made up of a substance called lignin. In some xylem vessels contains lignocellulose which is the complex structure of lignin and cellulose also present in it. They are long hollow chains of which are made up of tough long dead xylem cells. Each of the vessels is interconnected to each other through a perforation in their common walls. Xylem vessels are hydrophobic in nature i.e, cell wall shows the greater affinity for water. With the help of this particular property only xylem vessel function as transportation of water and solutes from the roots to all parts of a plant. 

So, the correct answer is option A.