Tag: water absorption and ascent of sap in plants

Questions Related to water absorption and ascent of sap in plants

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.

The phenomenon related to active water absorption 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. Transpiration

  2. Root pressure

  3. Osmotic pressure

  4. Translocation

Show answer
Correct Option: B
Explanation:

 Root pressure is the force in root region that helps to drive water or sap upwards into tracheary elements of xylem. Water is absorbed through the root hairs from the soil. When during low transpiration there is no transpiration pull that time root pressure increases and water moves upwards in xylem elements. Root pressure is actively push up the water to small height in the stem.

So the correct answer is 'Root pressure '.

Choose the correct answers from the alternatives given :
In which of the following plants metabolism would be hindered if leaves are coated with vaseline on their upper surface ?

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. Pistia

  2. VaIlisneria

  3. Lotus

  4. Mango

Show answer
Correct Option: C
Explanation:

Lotus have stomata on the upper surface of its leaves. Hence, Coating of Vaseline on its upper surface will hinder transpiration. 

Mango is a terrestrial plant which has stomata in the lower surface of leaves. Hence transpiration will not be affected in mango because of coating Vaseline on the upper surface.
So, the correct answer is lotus.

Choose the correct answers from the alternatives given.
When a cell is placed in 0.5 M solution of salt and no change in the volume of the cell is observed; the concentration of cell sap would be

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. 0.5 M

  2. 0.05 M

  3. 5.0 M

  4. 50 M

Show answer
Correct Option: A
Explanation:

When the concentrations of both the solution (cell sap as well surrounding solution) are same, there is no net movement in the cell. Such solutions are called isotonic solutions. Since it is specified that no change in volume occurs it means that the concentration of the cell sap will be same as that of the concentration of salt.

Hence, the correct answer is '0.5 M'.

Rate of water absorption generally follows closely the rate of

botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

  1. Transpiration

  2. Photosynthesis

  3. Respiration

  4. Growth

Show answer
Correct Option: A
Explanation:
The rate of transpiration is high on a bright sunny day. 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 A.

Water absorption through roots can be increased by keeping the plants

botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

  1. In the shade

  2. In dim light

  3. Under the fan

  4. Covered with a polythene bag

Show answer
Correct Option: C
Explanation:
  • Water absorption through the roots can be increased by keeping the plants under the fan. 
  • As by keeping the plants under the fan, the transpiration process is boosted. Therefore, more amount of water and other minerals are absorbed by the plant roots from the soil. 
  • The more is the rate of evaporation of water from the plants the greater is the rate of transpiration.
  • Hence Water absorption through roots can be increased by keeping the plants under the fan.
  • So, the correct answer is 'Under the fan'.

In root apoplast path of water transport; the water is transported through

botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

  1. Cell wall only

  2. Cell wall and inter cellular spaces

  3. Intercellular spaces

  4. Intercellular spaces, cell walls and endodermis.

Show answer
Correct Option: B
Explanation:

The water transport in the apoplastic pathway is through the cell membrane and the intercellular spaces. Water and solutes can pass freely through them.

This happens when water cannot enter the cells due to the presence of Caspian strips. 
So the correct answer is ' Cell wall and intercellular spaces'.