Tag: transport of water in plants

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

Organic and mineral nutrients undergo______

  1. Unidirectional

  2. Bidirectional

  3. Multidirectianal

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

Organic material in plants is transferred by phloem while water and mineral nutrients are transferred by xylem. It is a well-known fact that xylem only has unidirectional transport of water while phloem can exhibit bidirectional transport.

So, the correct answer is 'Both A and B'.

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

Pulsation theory was proposed by

  1. Godlewski

  2. Jagadish Chandra Bose

  3. Dixon and Joly

  4. Arthur
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Sir J.C. Bose proposed a theory of ascent of sap known as pulsation theory. 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 the cells were dead.
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

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

  1. Organic substances

  2. Inorganic substances

  3. Complex substances

  4. Insoluble substances
Reveal answer Fill a bubble to check yourself
B Correct answer
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'
Multiple choice botany water absorption and ascent of sap in plants apoplast and symplastic pathway transport of water in plants water transport

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

  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
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

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

First theory for ascent of sap was proposed by

  1. Westermeier

  2. Godlewski

  3. Bose

  4. Stephen Hales
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

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

Ringing experiments are performed to demonstrate

  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.
Reveal answer Fill a bubble to check yourself
D Correct answer
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.

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

Mostly minerals are absorbed from the soil by the plant 

  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
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

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

The chief role of transpiration in plants is to

  1. Remove surplus water

  2. Cooling of the plant

  3. Increase ascent of sap

  4. Uptake rise of minerals
Reveal answer Fill a bubble to check yourself
C Correct answer
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.