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

When an oak tree is kept in a poisonous solution, water rises to the top of the tree, although the tree is ready to take another supply of poisonous solution followed by uptake of even pure water. This shows that

  1. Living cells are not involved in ascent of sap.

  2. Living cells play a major role is ascent of sap.

  3. Both xylem and phloem play a major role in ascent of sap.

  4. Living cells play 60% role and vessels of xylem play 40% roles in ascent of sap.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Ascent of sap occurs through non living xylem tracheids and vessels. The force responsible for pull of water to great heights is the transpiration pull. The properties of adhesion, cohesion and capillarity helps in ascent of sap through non living tracheids and vessels.

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 statement is incorrect?

  1. Plants absorb excess quality of water

  2. Plants take small quantity of mineral salts through soil water

  3. Water and inorganic salts may also simultaneously by root hair

  4. Plant absorb only one thing at a time, i.e., either water or inorganic salts
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Plants absorb water through the entire surface - roots, stems and leaves. However, mainly water is absorbed by roots. They also absorb minerals like nitrogen, phosphorus, etc., from the soil through their roots. The root hairs which are in close contact with the thin film of water surrounding the soil particles absorb the mineral salts such as nitrates, chlorides, sulphates, phosphates, etc., dissolved in this water. However, the concentration of minerals in the soil is very low.

So, 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

Water will be absorbed by root hairs when

  1. Concentration of salts in the soil is high.

  2. Concentration of solutes in the cell sap is high.

  3. The plant is rapidly respiring.

  4. They are separated from the soil by a semipermeable membrane.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Water moves from a region of its own high concentration to a region of its own low concentration. If the cell sap is highly concentrated as compared to soil solution- it means water molecules are present in high concentration in the soil solution and in low concentration in the cell sap. In such a situation water molecules will move along their concentration gradient and readily move inside the root hairs.

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

Pulsation theory to explain ascent of sap in Desmodium was proposed by

  1. Dixon and Jolly

  2. Curtis

  3. J. C. Bose

  4. None of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

"Pulsation" or "Vital force" theory was a proposed mechanism for the ascent of sap through the xylem tissue of plants according to which, the conduction of water up the xylem vessel is a result of vital action of the living cells in the xylem tissue.
Jagadish Chandra Bose suggested this mechanism for the ascent of sap in 1927. He found electrical pulsations or oscillations in electric potentials, and came to believe these were coupled with rhythmic movements in the telegraph plant Desmodium. However, this theory has now been rejected by majority of plant physiologists.

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

By which process absorbed water reaches upto the leaves?

  1. Transpiration

  2. Photosynthesis

  3. Nitrogen fixation

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
 The physiological process of transpiration creates a suction pull that is transmitted down to the root through water column in the xylem elements. This pulls water from the roots to the leaves. 
So, the correct answer is 'Transpiration'
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 helps in ascent of sap?

  1. Root pressure

  2. Transpiration

  3. Capillarity

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

The mechanism of the ascent of sap in plants occurs due to the activity of the living cells. The factors responsible are
root pressure-  plant roots absorb the excess of water by an active process and builds up a hydrostatic pressure within the root system, called root pressure.  This activity pushes the water upwards all along the length of the stem.
Transpiration -The pulling force that operates on xylem water columns is called Transpiration Pull or Suction Pressure.
Capillary action along with the root pressure, the ascent of sap is mainly due to passive forces that develop within the plant, due to certain environmental factors that act upon the plant.  tracheids and vessels of the xylem behave as capillary tubes. Ascent of sap is partly due to the capillarity of these tissues. 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 water is the xylem elements develop tension when

  1. Rate of transpiration and the rate of absorption both are high

  2. Rate of transpiration is very slow and the rate of absorption is high

  3. Rate of transpiration is very high and the rate of absorption is slow

  4. Rate of transpiration and the rate of absorption both are very slow.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

As water is lost from the surface of the leaves due to transpiration a strong suction force is transmitted through the active mesophyll cells to the ends of the water column in root thus is called transpiration pull. It caused the entire water column to be pulled upwards. When the rate of transpiration is very high and the rate of absorption is slow, the water in the xylem elements of the leaf develops a state of tension.
So, the correct answer is C.
Multiple choice botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

The _______ in the xylem tissue of plants is the upward movement of water and minerals from the root to the crown.

  1. Ascent of sap

  2. Parenchyma

  3. Vessels

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

When a Balsam plant is provided with a dilute solution of safranine, the same is absorbed by the root system and transported upwards which can be easily traced because of the red color of the safranine that binds and stains the cells responsible for 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

Which of the following force accounts for the ascent of sap?

  1. Adhesive force

  2. Cohesive force

  3. Transpirational pull

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

The ascent of sap is the mechanism by which water moves from the roots to the top of the trees. Studies on the process of an ascent of sap show that the strong cohesive force between the water molecules (cohesion), the attraction between water molecules and the wall of the xylem elements (adhesion) and the transpiration pull creates a tension on the water column, which ensures continuity of water column in plants. The water lost from the leaves during transpiration creates a high solute potential and reduces water potential. The reduced water potential creates a suction pull and allows ascent of sap. 

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

Which of the following theory gave the most satisfactory explanation for the ascent of sap?

  1. Relay pump theory

  2. Transpirational pull theory

  3. Root pressure theory

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The transpiration pull theory is the most accepted theory for the ascent of sap. Dixon and Jolly gave transpiration pull theory. According to this theory, the ascent of sap in plants is a passive physical process, which occurs under the influence of transpiration pull generated due to loss of water from aerial parts. The water lost from the leaves creates a high solute potential and reduces water potential. The reduced water potential creates a suction pull and allows ascent of sap. Other than the pull, a continuous column of water is also essential for the rise of water in xylem elements. The continuous column of water is maintained by cohesion forces between water molecules and adhesive forces between water molecules and vascular elements of the plant.

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

Which of the following statements was supported by Westermaier?

  1. The upward conduction of water is provided by cohesive force.

  2. The upward conduction of water is provided by xylem parenchyma cells.

  3. The upward conduction of water is provided by pulsatory action of living cells.

  4. None of the above.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

There are several vital theories which help in understanding the concept of the conduction of water by xylem. Westermaier explained the theory that the upward conduction of water is due to xylem parenchyma cells. The tracheids and the vessels act as water reservoirs. This allows the movement of the water in upward direction. 

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

Which part helps the plant absorb water and mineral from the soil?

  1. Root hairs

  2. Roots

  3. Root cap

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

Tap root is a type of roots which has a major big central root and small branching. These go very deep in the soil and are very strong.

Root cap helps the root to grow in length by cell division.
Roots are the general organs of the plants that absorb water but more specifically it is the root hair present on the root that significantly increase the surface area available for absorption of water and minerals.
So, the correct answer is 'Root hairs'.

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

Water in plants is transported by or ascent of sap takes place through 

  1. Cambium

  2. Phloem

  3. Xylem

  4. Epidermis
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Xylem contributes in ascent of sap by the following phenomena.
1) The rate of transpiration is high. 
2) The water is lost from guard cell which leads to decrease in the water potential of guard cell as compared to the surrounding cell. 
3) To stabilize the water potential in the guard cell water rushes from the neighbouring cell which creates a cohesion pull in the xylem vessels to pull the water up to the guard cell. 
So, the correct answer is option C.
Multiple choice botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

Ascent of sap is

  1. Upward movement of water in the plant.

  2. Downward movement of organic nutrients.

  3. Downward and upward movement of water in the plant.

  4. Redistribution of inorganic substances in the plant.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • Down to upwards movement is known as ascent and Top to downwards movement is known as descend.
  • In plants sap is water and minerals.
  • Ascent of sap in the xylem tissue of plants is the upward movement of water and minerals from the root to the top. 
Multiple choice botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

The transport of sap from root to top of the plant is

  1. Ascent of sap

  2. Conduction

  3. Transport

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

When any material movement is from down to upwards it is called as ascending movement.

When material movement is from top to downwards it is called as descending movement.
The upward movement of water and minerals from the root to the top of the plant is called as ascent of sap. Plants absorb water through the root hairs and transpire through leaves. The water moves from the root to the tip portion of the plant body against the force of gravity by transpiration pull.