Biology

Plant Transport and Physiology

1,834 Questions

Access a comprehensive set of questions on plant transport mechanisms and physiological adaptations. Topics include water movement, translocation of food, and plant responses to external stimuli. These biology questions are essential for medical entrance exams and other science competitive tests.

Xylem and phloem transportTranspiration and evaporationPlant adaptationsGeotropic and phototropic responsesWater absorption by rootsRespiration in roots

Plant Transport and Physiology Questions

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

Transportation is helpful to plants in 

  1. Cooling

  2. Loss of excess nutrients

  3. Upward conduction/ascent of sap

  4. Loss of excess water
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Transportation is the process involving the transfer of materials from one place to another place.

(A)In plants, cooling occurs through transpiration.
(B)Plants loss excess nutrients and water through their aerial parts.
(C)Transportation helps in the ascent of sap or food.
(D)Transpiration is the loss of excess water.
So, the correct answer is 'Upward conduction/ ascent of sap'.

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

According to the vital force theory, ascent of sap is due to active pulsation of the innermost layer of cortex. This theory was given by 

  1. J. C. Bose

  2. Dixon

  3. Strasburger

  4. Sachs
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

According to the vital force theory, ascent of sap is due to active pulsation of the innermost layer of cortex. This theory was given by J.C Bose. The pulsation theory states that water is absorbed by the plants due to the metabolic activity of living cells which are in constant state of rythmatic pulsation. But it was not accepted as water can be passively absorbed by the roots even when the cells were dead.

So, the correct answer is option A.

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

In plants, water moves from 

  1. Less negative to more negative gradient

  2. More negative to less negative gradient

  3. Similar gradient

  4. Zero gradient
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
In plants, water is absorbed by roots from the soil and it has to get transported to all parts of the plant. Water moves only from the more negative gradient to a less negative or positive gradient. As when water concentration is high then the gradient is more negative and water always move from the higher concentration to lower concentration.
So, the correct answer is 'More negative to less negative gradient'.
Multiple choice botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

The rupture or fractionation do not usually occur in the water coloumn in vessels / tracheids during the ascent of sap because of

  1. lignified thick walls

  2. cohesion and adhesion

  3. weak gravitational pull

  4. transpiration pull
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The rupture or fractionation do not usually occur in the water column in vessels/ tracheids during the ascent of sap because of cohesion and adhesion. This is because continuity of water column is maintained by cohesion and adhesion. The conduction of water from root to aerial parts of plants is called ascent of sap. The water molecules remain attached to each other by cohesion force. The magnitude of this force is very high. This helps in the continuous water column in the xylem. The adhesive force is present between the water molecules and the walls of xylem. This also helps in continuous water column in the xylem.

Thus, the correct answer is option B.

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

A column of water within xylem vessels of tall trees does not break under its weight because of

  1. Dissolved sugar in water

  2. Tensile strength of water

  3. Lignification of xylem vessels

  4. Positive root pressure
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The tensile strength of water is its ability to resist the effect of external stress and maintain it's flow. The transpiration all pull exerts great stress on the water column but due to its tensile strength, it doesn't break in between.

Dissolved sugar increases the solute potential while root pressure provides a push to water only up to a certain extent.
Lignin provides mechanical support to the xylem vessels.
So the correct answer is 'Tensile strength of water'.

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

Rising column of water does not break its connection with xylem walls despite negative pressure or tension due to

  1. Cohesion amongst water molecules

  2. Strong transpiration pull

  3. Adhesion

  4. Surface tension
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
The attraction between the molecule of dissimilar substances is called adhesion. Walls of tracheid and vessels of xylem are made up of lignin and cellulose and due to adhesive force, they have a close affinity for water. Thus, a rising column of water does not break its connection with xylem walls despite negative pressure or tension. 
So the correct answer is 'Adhesion'.
Multiple choice botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

Root pressure theory cannot explain the ascent of sap because it is not found in 

  1. Bryophytes

  2. All plants and in all seasons

  3. Trees

  4. Spring
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Root pressure theory is proposed by Priestly. It is defined as the pressure which set up in the cortical cells of the roots due to the osmotic action under which water passes from the living cells of the root in the xylem and thus helps in the ascent of sap. The ascent of sap also occurs in plants without roots and root pressure. Thus this theory cannot explain the ascent of sap.
So the correct answer is 'All plants and in all season'.
Multiple choice botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

Which of the following factor is responsible for the transpirational pull?

  1. High water potential in the leaf

  2. Low water potential in the leaf

  3. High solute potential in leaf

  4. Both B and C
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Transpiration is the process of water movement from soil solution into the plants and then to the atmosphere. The direction and intensity of water movement are determined by the difference in the water potential gradient between the two regions. The water potential in the leaf is lower which allows the movement of water in the upward direction. When the water potential is low, the solute potential is high. 

Thus, the correct answer is option D. 

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

Guttation is caused due to

  1. High water potential.

  2. High root pressure.

  3. Low transpiration.

  4. All of the above.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Guttation is the loss of water in liquid form as a dilute solution from the leaf tips. The uninjured leaf tips have hydathodes or water stomata. Under conditions of low transpiration dilute solution of minerals oozes out through them under the influence of increased root pressure. Water potential depends on the number of water molecules in the system. More the number of water molecules, greater will be the water potential. Under the conditions, when there are more water molecules in the system, water potential is expected to be higher. There is more water molecules will be stuffed up inside leaf in the intercellular spaces giving rise to a positive water potential. There is low transpiration and guttation takes place.

Thus, the correct answer is option D. 

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

The cut end of a shoot is dipped in eosine solution. What will happen?

  1. Ascent of sap does not occur.

  2. Ascent of sap does not occur but the leaves remain fresh.

  3. Leaves will but ascent of sap continues.

  4. Ascent of sap occurs and the tracheary elements get stained.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Eosine solution is a $1%$% alcoholic staining solution, that can be used for the staining of plant elements.
When a cut end of the stem is dipped in eosine solution, then due to concentration gradient diffusion occurs and hence ascent of sap occurs. Since it is staining agent it stains the tracheary elements.
So the correct answer is 'Ascent of sap occurs and the tracheary elements get stained'.
Multiple choice water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

Choose the correct answers from the alternatives given.
What role cohesion and adhesion play in xylem transport?

  1. Like transpiration, they create a tension

  2. Like root pressure, they create a positive pressure

  3. Like sugars, they cause water to enter xylem

  4. They create a continuous water column in xylem
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Cohesion is the mutual attraction between water molecules. Adhesion is the attraction of water molecules to polar surfaces (such as walls of xylem vessels). These both forces together helps in the formation of a thin, unbroken column of water which leads to the mass flow of water in apoplastic pathway.

Hence, the correct answer is 'They create a continuous water column in xylem'.

Multiple choice biology movement in and out of the cell diffusion across cells diffusion and osmosis inter cellular movement

When a plant cell is placed in a hypertonic solution it becomes plasmolysed. What shall be present between cell wall and plasmalemma at this stage?

  1. Water and air

  2. Cell sap

  3. Hypertonic solution

  4. Solutes
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Plant cells are surrounded by a dead cellulosic cell wall. The plant cell wall is fully permeable and cannot regulate the entry or exit of solutes or solvent. When a plant cell is present in a hypertonic solution plant cell will lose water through exosmosis. As the plant cell keeps on losing water, the protoplasm shrinks and moves away from the cell wall, the hypertonic solution moves inside the space between cell protoplasm and cell wall. 

Multiple choice bio-chemistry absorption by roots - the processes involved osmotic relations of plant cells transport across membrane imbibition and its importance

Plant cells do not burst in distilled water, because

  1. Cells wall is rigid and do not get overstretched

  2. Cell wall is living

  3. Cell wall is the outer most layer of plant cell

  4. Cell wall is permeable
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Cell wall is the outermost, rigid, protective, non living and supportive layer found in all the plant cells. Due to its rigid nature it prevent the cell from bursting. It is not found in animal cells. An animal cell placed in pure water will swell up and burst, because of endosmosis.

Multiple choice bio-chemistry absorption by roots - the processes involved osmotic relations of plant cells transport across membrane imbibition and its importance

Glucose is not stored in plants due to its ability to 

  1. Decrease osmotic pressure

  2. Increase osmotic pressure

  3. Increase turgor pressure

  4. Decrease turgor pressure
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

  • Osmosis occurs only through the semi-permeable membrane. Osmosis is a gradient dependent process, osmosis is different from diffusion as it is characterized by a semi-permeable membrane.
  • Net direction and rate of osmosis depend on both pressure gradient and concentration gradient.
So, the correct answer is 'Increase osmotic pressure'.