Tag: water absorption and ascent of sap in plants

Questions Related to water absorption and ascent of sap in plants

Which substances do the plants obtain from the soil for the constitution of the body?

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

  1. Organic substances

  2. Inorganic substances

  3. Complex substances

  4. Insoluble substances

Show answer
Correct Option: B
Explanation:
Soil contains a large number of inorganic substances in the form of ions which are taken up by the plant through process called ascent of sap
So, the correct answer is 'Inorganic substances'

Who found that overlapping cuts do not hinder ascent of sap

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

  1. Askenasy

  2. Preston

  3. Mac Dougal

  4. Priestly

Show answer
Correct Option: A

Theory of 'Ascent of Sap' was given by Dixon and Jolly. Which of them is against the theory?

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

  1. Cohesive and adhesive properties of H$ _2$O

  2. Requirement of ATP

  3. Presence of pores in the tracheary elements

  4. All of the above

Show answer
Correct Option: B
Explanation:

Ascent of sap theory is based on transpiration pull of a continuous water column in the xylem elements of plants. The continuous water column is generated because of adhesion and cohesion forces, operating between water molecules and xylem elements and between water molecules respectively. The pull is generated passively due to loss of water during transpiration and does not requires input of energy. Hence, there is no requirement of ATP in ascent of sap and it is a physical process only.

First theory for ascent of sap was proposed by

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

  1. Westermeier

  2. Godlewski

  3. Bose

  4. Stephen Hales

Show answer
Correct Option: B
Explanation:

The first theories proposed to explain ascent of sap were Vital force theories. These theories believed that living cells are involved in the ascent of sap, e.g., relay pump theory by Godlewski, 1883 and Pulsation theory by Bose, 1923.  

Bose believed that the inner most cortical cells pump water into the interior that contains xylem channels. The vital force theories have been discarded because as proved by Boucherie in 1840 and Strasburger in 1891 water rises up the stem even when all the living cells are killed by poison or heat.

Ringing experiments are performed to demonstrate

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

  1. Ascent of sap through both phloem and xylem.

  2. The ascent of sap through phloem and xylem parenchyma.

  3. The ascent sap through cortical cells.

  4. Ascent of sap through xylem.

Show answer
Correct Option: D
Explanation:

In ringing experiment the bark of a tree is removed at a height above the soil surface as a ring. This leads to accumulation of sugars just above the ring of bark removal because sugars are transported through phloem. The ascent of sap which occurs through xylem continues normally because xylem is not part of the bark and bark consists of secondary phloem along with several other tissues.The experiment clearly demonstrates the function of xylem.

Thus, the correct answer is option D.

Mostly minerals are absorbed from the soil by the plant 

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

  1. By a process dependent of water absorption

  2. Only when soil solution is hypotonic to cell sap

  3. Only when soil solution is hypertonic to cell sap

  4. None of the above

Show answer
Correct Option: A
Explanation:

In soil, the minerals can be present dissolved in soil solution or adsorbed on charged clay particles. Plants obtain minerals both from the soil solution (through absorption) as well as directly from clay particles (through ion exchange mechanisms). 

Mineral absorption can be active or passive. The passive mineral absorption can occur both in the direction as well as against concentration gradient. Mass flow is one mechanism through which minerals are absorbed passively against their concentration gradient. In mass flow, mineral ions are swept into root and passed into the plant parts along the current of water, caused by transpiration pull. Mineral absorption depends on water absorption because the solvent of soil solution is water. Mineral absorption can occur along with the water stream. Minerals can also be absorbed actively involving the expenditure of metabolic energy irrespective of the tonicity of the soil solution.
So, the correct answer is option A.

The chief role of transpiration in plants is to

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

  1. Remove surplus water

  2. Cooling of the plant

  3. Increase ascent of sap

  4. Uptake rise of minerals

Show answer
Correct Option: C
Explanation:

According to the most widely accepted theory, ascent of sap occurs through 'Cohesion Tension' or 'Cohesion Transpiration pull'. The cohesion and adhesion forces give rise to a continuous water column in xylem elements, which is lifted by the transpiration pull. Thus, ascent of sap is purely physical process and does not involves energy input.

The main path for movement of water against the force of gravity i.e., ascent of sap in herbaceous dicots is

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

  1. Tracheids

  2. Vessels

  3. Sieve tubes

  4. All of the above

Show answer
Correct Option: B
Explanation:

Xylem tissue is a complex permanent tissue specialized to transport water in plant body. Xylem tracheids are found in a number of plant groups like angiosperms, gymnosperms and pteridophytes. Bryophytes do not possess vascular tissues. Hence, bryophytes do not attain height. Xylem tracheids are present in pteridophytes and gymnosperms. These plant groups lack vessels. Vessels are characteristics of angiosperms only. In angiosperms, xylem vessels form the main channel for ascent of sap.

Vital theories of ascent of sap were discarded due to reasons that

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

  1. Living cells are involved.

  2. Metabolic activity provides energy requirements.

  3. Water continues rising even after killing of xylem parenchyma.

  4. Atmospheric pressure is involved in ascent of sap.

Show answer
Correct Option: C
Explanation:

Vital force theories were propagated to explain the ascent of sap. These theories believed that living cells are involved in the ascent of sap e.g., relay pump theory by Godlewski, 1883 and pulsation theory by Bose, 1923. Bose believed that the inner most cortical cells pump water into the interior, that contains xylem channels. The vital force theories have been discarded because as proved by Boucherie in 1840 and Strasburger in 1891 that water rises up the stem, even when all the living cells are killed by poison or heat.

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

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

  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.

Show answer
Correct Option: A
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.