Tag: water absorption and ascent of sap in plants

Quizzes (6) Questions (154)

Questions Related to water absorption and ascent of sap in plants

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

Relay pump theory of ascent of sap was proposed by

  1. Bose

  2. Godlewski

  3. Westermaler

  4. Von sachs
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Godlewski proposed relay pump theory to explain ascent of sap. According to him there was a rhythmic change in the osmotic pressure of the living cells of xylem parenchyma and medullary rays, which brought about a pumping action of water in an upward direction.

The tracheids and vessels acted as water reservoirs. Janse supported Godlewski and showed that if the lower portion of branch was killed, the leaves above were affected.


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

Capillary force theory to explain ascent of sap was proposed by

  1. Boehm

  2. Sachs

  3. Jamin

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

Capillarity Theory: It is given by Boehm (1809). According to this theory, water is translocated because water molecules adhere to the surfaces of small, or capillary, tubes. This adhesion causes water to somewhat creep upward along the sides of xylem elements. In glass tubes this upward movement is visible as the curved or crescent-shaped (concave) meniscus. However, it was shown that capillarity (or capillary rise) alone in tubes of similar diameter as that of a xylem element raises water less than 1 meter.

Hopkins (1999) explained that the relationship between the rise of water in a capillary tube and the size of the tube is inversely proportional. This means that the thinner is the tube, the higher will be the rise of water.

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 plant is ideal to demonstrate 'Ascent of sap'?

  1. Rose plant

  2. Balsam plant

  3. Coconut plant

  4. Cucumber plant
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The passage of absorbed water from root to the aerial parts of the plant is known as the ascent of sap. It occurs through xylem (lumen of tracheary elements or vessels and tracheids) with a rate of 10 to 75 centimetres per minute. This can be demonstrated by ringing experiments (conducted by Malpighi, 1672; Stephen Hales, 1727; and Hartig in 1837) or dipping the cut end of a fresh shoot (e.g., Balsam) in 2 percent eosin solution for about 30 minutes. Then, the veins of the leaves turn red. Sections through stem and leaves indicate that the xylem vessels/tracheids turn red.

Thus, the current 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

Ringing experiment to explain ascent of sap path was first done by

  1. Hartig and Malpighi

  2. Dixon and J. C. Jolly

  3. Godlewski and J. C. Bose

  4. Stephen hales and Boehm
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Downward translocation of the organic solutes takes place through phloem. This can be proved by the ringing experiment. Ringing experiment was carried by Hartig, Malpighi and Stephen Hales.
They took a branch with leaves immersed in beaker which is filled with water. Now remove all the tissues which are present above the xylem [cortex, cambium and phloem]. Now placed this experiment in a suitable environment for 2 - 3 days. Then they observed that leaves did not wilt. This experiment makes it clear that water moves up only through vessels and tracheids of the xylem. 
Ringing [girdling] experiment has been done only in dicotyledons because their vascular bundles lies in a ring. While vascular bundles are scattered in monocotyledons, so that this experiment can not be possible.

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

Sir J.C. Bose was supporter of _________ ascent of sap.

  1. Root pressure theory

  2. Physical force theory

  3. Vital force theory

  4. None of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Vital force theory:-
Berzelius proposed the origin of organic components by the vital force theory. According to today's organic components of synthesized only within living species.
Physical force theory:-
Godlewski explains the vertical movement of water to the plant. He said that changes in the water potential of the living cells like xylem parenchyma and medullary rays caused to raise water against gravity.
Root pressure theory:-
 It is proposed by Priestly. According to this theory, the water which is absorbed by the root hairs from soil collects in the cortical cells which becomes fully turgid. This pressure forces the water up to the xylem cells. 

Hence, 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 following evidences rejected the atmospheric pressure theory. Which of them is correct?

  1. It can raise water to height of 33 feet only if complete vacuum is created.

  2. Free surface of water is required for proper operation of atmospheric pressure, which is readily available in plants.

  3. Pressure falls below that of atmospheric pressure because of transpiration.

  4. Water rises rapidly to compensate the water loss, because of atmospheric pressure.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Atmospheric pressure theory was advanced to explain ascent of sap in plants. The protagonists of this theory have assumed that plants are closed systems. When water escapes by transpiration from the surface of the leaves, it is believed that vacuum will be created within the plant body. As the root system is submerged in soil water, with the atmospheric action on the soil water, in order to fill up the vacuum created in the xylem vessels, water just enters passively; thus, the water is translocated upwards. But it was later on concluded that plants are not closed systems but they exhibit openness, for, the gases can diffuse into and out of the plant system with ease and facility. Added to this, atmospheric pressure can support the water to be lifted only to a height of 34 feet; but there are plants which are taller than this and still there is transport of water. Hence it can be concluded that atmospheric pressure could not be the force 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

The imbibition theory for the ascent of sap was suggested by

  1. Sir J. C. Bose

  2. Strassburger

  3. Sachs

  4. Dixon and Jolly
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Imbibitions theory was proposed (1868) and supported by Sachs (1878). According to this theory the ascent of sap occurs due to imbibitonal activity of the cell walls of the xylem elements.

This theory is discarded as it has been experimentally found that water rises up through the lumen of the xylem and not through the walls.

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.