Tag: mineral absorption

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Multiple choice botany plant physiology mineral absorption transport of food, water and minerals mineral transport theories of translocation transport in the phloem of plants

A rising column of water does not break its connection in the xylem vessels, despite negative pressure or tension due to

  1. Cohesion among water molecules

  2. Strong transpiration pull

  3. Adhesion

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

Cohesion-Tension or Cohesion Transpiration pull theory was put forward by Dixon and Jolly in 1894. It is also known as Dixon's theory of Ascent of Sap. The important points are: 

1. Cohesion (attractive force between water molecules) and Adhesion (attractive force between water and xylem channels) Forces.
2. Continuous water columns.

3. Transpiration pull.
Water molecules are held together by strong cohesion force which is due to hydrogen bonds amongst them. It is due to these forces that water forms a continuous column in xylem elements. If there is an air bubble or air gap in this continuous column then water will not rise in the xylem elements. This break in rise of water is called as cavitation.

Thus, the correct answer is option A.

Multiple choice botany plant physiology mineral absorption transport of food, water and minerals mineral transport theories of translocation transport in the phloem of plants

Which one explains ascent of sap ?

  1. Cohesion-tension theory of Dixon and Joly

  2. Starch-sugar interconversion

  3. Photosynthesis

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
(A)Cohesion transpiration pull theory proved that cohesion and adhesion support continuity of water columns and provide strength like a steel wire, transpiration pulls water columns towards leaves which causes ascent of sap.
(B)Starch sugar theory was given by Steward proposing that during daytime enzymes phosphorylase and converts starch into sugar increasing the osmotic potential causing ascent of sap.
(C)Photosynthesis is the process of formation of complex compounds, glucose using simple compounds like carbon dioxide, sunlight.
So, the correct answer is 'Cohesion-tension theory of Dixon and Jolly'.
Multiple choice botany plant physiology mineral absorption transport of food, water and minerals mineral transport theories of translocation transport in the phloem of plants

Most widely accepted theory of carbohydrate translocation is

  1. Mass flow theory

  2. Root pressure theory

  3. Imbibition theory

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

(A) Mass flow theory proposes the transportation of food in the plants.

(B) Root pressure theory proposes the transportation of water in the plants through the root pressure.
(C) Imbibition theory proposes water transportation through pipes.
(D) Transpiration theory proposes water transportation due to the evaporation from the upper surface of the leaves.
So, the correct answer is 'Mass flow theory'.

Multiple choice botany plant physiology mineral absorption transport of food, water and minerals mineral transport theories of translocation transport in the phloem of plants

Munch hypothesis is based on translocation of food due to

  1. Imbibition force

  2. Turgor pressure (TP) gradient

  3. Both A and B

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

Munch hypothesis is also called the pressure flow hypothesis, it explains the movement of sap through the phloem. It proposed by Ernest Munch in 1930. High concentration of organic substance inside the cell of the cells of the phloem at a source that creates the diffusion gradient drawing water from the adjacent xylem resulting into the turgor pressure.

So, the correct answer is 'Turgor pressure gradient'.

Multiple choice botany plant physiology mineral absorption transport of food, water and minerals mineral transport theories of translocation transport in the phloem of plants

Mass flow hypothesis was first described by ___________.

  1. Swanson

  2. Buchman

  3. Kursanov

  4. Munch
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Mass flow or pressure flow hypothesis was put forward by Munch $(1927, 1930)$. According to this hypothesis, organic substances move from the region of higher osmotic pressure to the region of lower osmotic pressure in a mass flow due to the development of a gradient.

So, the correct answer is 'Munch'

Multiple choice botany plant physiology mineral absorption transport of food, water and minerals mineral transport theories of translocation transport in the phloem of plants

Presence of bicollateral vascular bundle provides evidence that conduction of food takes place through the

  1. Phloem

  2. Xylem

  3. Both A and B

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

Translocation of prepared food occurs through the phloem. Bicollateral vascular bundles have two patches of phloem. Bicollateral vascular bundles show following arrangement of vascular tissue, outer phloem, outer cambium, xylem, inner cambium, inner phloem. These vascular bundles can transport much more amount of sugars than collateral vascular bundles having only a single patch of phloem. Bicollateral vascular bundles are common in Family Cucurbitaceae with large leaves, large fruits called Pepo and thin weak stems. 

Multiple choice botany plant physiology mineral absorption transport of food, water and minerals mineral transport theories of translocation transport in the phloem of plants

According to Dixon and Jolly, cohesive force of water molecules is of the magnitude of ...............

  1. 1 - 10 atm

  2. 10 - 15 atm

  3. 45 - 200 atm

  4. 15 - 45 atm
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

One atmospheric pressure of transpiration pull is enough to pull the water unto the height of 20 feet or so; but normally, the transpiration pull that develops runs to about 20-100 atm (it can be as high as 200 atms in case of rapidly transpiring tall trees in tropics), which is enough to pull the water to the height of 400 to 1000 ft and the tallest plant known to mankind is just about 400 ft. 

Multiple choice botany plant physiology mineral absorption transport of food, water and minerals mineral transport theories of translocation transport in the phloem of plants

Which one is against the theory of ascent of sap by Dixon and Joly?

  1. Pores in tracheary elements

  2. Cohesion force of water molecules

  3. Adhesion force of water molecules

  4. Requirement of ATP
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Dixon and Joly gave the theory that ascent of water in the plant through pored tracheary elements of xylem which uses cohesion-tension, transpiration pull and suction pressure developed in the leaf cells.

According to this theory, there is no use of energy or ATP for the ascent of the sap.
So, the correct answer is 'Requirement of ATP'.

Multiple choice botany plant physiology mineral absorption transport of food, water and minerals mineral transport theories of translocation transport in the phloem of plants

Which of the following is appropriate for mass flow hypothesis?

  1. Large amount of ions are also absorbed alongwith absorption of water.

  2. As suction pressure increases, absorption of water increases and along with water, absorption of ions also increases.

  3. Transpiration pull is responsible for absorption of ions.

  4. All the above.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Mass flow hypothesis is also known as the pressure flow hypothesis. It was proposed by Ernst Munch in 1930. 
During this process, the large number of ions are absorbed along with the absorption of water. Due to an increase in suction pressure and transpiration pull, absorption of water and ions increases. 
So the correct answer is 'All of the above'.
Multiple choice botany plant physiology mineral absorption transport of food, water and minerals mineral transport theories of translocation transport in the phloem of plants

Cohesion transpiration pull theory of ascent of sap was proposed by 

  1. Munch

  2. Stephen Hales

  3. Dixon and Joly

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

Cohesion transpiration pull theory was proposed by Dixon and Jolly. They proved that cohesion and adhesion support continuity of water columns and provide strength like a steel wire, transpiration pulls water columns towards leaves which causes ascent of sap.

So, the correct answer is 'Dixon and Jolly'.