Translocation of organic nutrients from the region of source or supply to the region of sink or utilisation is mostly in the form of sucrose. Phloem (sieve tubes or sieve cells) is the pathway for this translocation, as found put by stem girdling, sieve tube puncturing, radioautography and chemical analysis of sieve tube sap.

• The cohesion-tension theory is a theory of intermolecular attraction that explains the process of water flow upwards (against the force of gravity) through the xylem of plants. 
• Transpiration pull, utilizing capillary action and the inherent surface tension of water, is the primary mechanism of water movement in plants. 
• Hence, The cohesion transpiration pull theory operates only in Conditions favouring transpiration.
• So, the correct answer is 'Conditions favouring transpiration'.

In vascular plants, water and minerals move through xylem, whereas sugars move through phloem. Ringing experiments prove that sugars move through phloem. If the phloem tissue is removed in a ring or girdle, the sugars cannot be transported to roots from aerial parts and plant dies. 

Dixon explained ascent of sap in trees based on transpiration, cohesion, adhesion theory. Mac Dougal supported transpiration pull theory through experimental proof. Cohesive force and adhesive force works continuously in the cavity (lumen) of xylem. Both the forces are responsible for maintaining unbroken continuity of water column from the roots to the leaves.

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: 

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

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.

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.

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. 

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. 

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.

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.

Cohesion tension theory was proposed by John Joly and Henry Horatio Dixon in the year 1894. The theory has two fundamental features such as (i) cohesion of water and adhesion between water and xylem tiusses, (ii) Transpiration pull. This theory explains plants which is responsible for the movement of water column upward.

Mass flow hypothesis is also known as pressure flow hypothesis it is the best-supported theory to explain the movement of sap through the phloem. It was discovered by the scientist by Ernst Munch in 1930, He was the German plant physiologist. This creates the hydrostatic pressure in the phloem of the plant.

Cell membrane, also known as plasmalemma, is the innermost membrane of a plant cell. It is surrounded by a cell wall. The cell membrane is a selectively permeable membrane that allows only some type of compounds to pass through. The membrane has a phospholipid structure that contributes to this property.

Xylem tissue is comprised of dead cells involved in the process of transport of water and minerals. Transport of water is under the influence of transpiration pull and is a physical process. 

Phloem is involved in transport of sugars. Phloem cells are living cells, which carry out the physiological process of sugar transport in higher plants.

Movement of food takes place through phloem tissue. This can be demonstrated through ringing experiment in which, if ring of vascular tissue including phloem is removed in a dicot tree. The plant parts located below the point of ringing will die because these parts do not get food.

The absorption, distribution and metabolism of various mineral elements by plants are called mineral nutrition. The mineral elements play important role in the performance and maintenance of life activities. All microelements are absorbed by plants in traces and derived from the parent rock by the process of weathering. 

A nutrient which is required in small quantities is called as a micronutrient. The micronutrients are boron, chlorine, copper, iron, manganese, molybdenum and zinc. These plant food elements are used in very small amounts, but they are just as important to plant development and profitable crop production as the major nutrients. Especially, they work "behind the scene" as activators of many plant functions.

Ammonium sulfate is a fertilizer as it increases the fertility of soil and plants can use it for their functions.

Whenever active transport is being carried out energy is required and ATP is used up as it is the energy currency of the cell.

The active transport of substances require energy and hence they use up ATP which is the energy currency of the cell.

Trace elements are the ones which are required in. Very less amount and are present in less amounts as compared to other elements of major use.

The root nodule bacterium is microaerobic in the sense that it requires oxygen but the high concentration of oxygen is detrimental to nitrogen-fixing enzyme system. Here leghaemoglobin proves beneficial, it absorbs or binds oxygen so that there is no free oxygen left in the nodule and then carries micro-amounts of oxygen to the nodule bacteroids. Thus the correct answer is option B.

Boron regulates pentose phosphate pathway, increases sugar translocation in plants. Due to deficiency of boron growth of roots stops and the disease ' brown heart' is caused in sugarbeet. Thus option A is the correct answer.

The Pressure flow hypothesis often regarded as mass flow hypothesis explains best about the movement of Plant sap through phloem .The concept was proposed by E.Munch . The transpiration of water from leaves and other part of plant body produces negative pressure inside transport vessels causing root to absorb large amount of water along with ions to maintain the continuity of column of water . 

The mineral salts are absorbed into the symplasm, i.e., cytoplasm of root cells. There are special specific mineral transporters present in the plasma membrane of cells, which absorb the minerals from soil solution by transporting them across the membrane from soil solution to the cytoplasm of root cells. This way minerals can be absorbed irrespective of or against the concentration gradient of minerals. The minerals are present in the soil solution at very low concentrations and are usually absorbed against the concentration gradient with the help of specific carriers.

The roots respire continuously giving out carbon dioxide into the rhizosphere. Carbon dioxide combines with water and forms carbonic acid. Carbonic acid dissociates into  H$^+$ and HCO$ _3$$^-$. Because of high respiratory activity, a zone of carbonic acid is developed in root tips. The H$^+$ ions are exchanged with cations adsorbed on the clay micelle. The cations then come into the soil and diffuse onto the root surface. This is the carbonic acid exchange theory. Thus the correct answer is option C.

Soil respiration refers to the production of carbon dioxide when soil organisms respire. They include roots and other microbiota. Roots continuously respire and liberate significant quantities of CO2. The CO2, when dissolved in soil water, produces carbonic acid.  Immediately they ionize into H+ and bicarbonate ions. Thus during respiration in plant root carbonic acid is formed. Thus the correct answer is option C.

According to the theory of ions put forth by Jenny and Overstreet, ions are transferred from soil to root or vice versa without passing into solution. The ions are electrostatically adsorbed to the surface of root cells and are held tightly. These ions oscillate within a small volume of space called oscillation volume. When the oscillation volume of two ions of same charge overlap one ion is exchanged for the other. This is called contact exchange. Thus the transfer of ions from soil to root takes place without passing into solution. Thus the correct answer is option D.

Plant root cells contain relatively large quantities of organic cations and anions that do not diffuse through cell membranes. These organic ions could act as non-diffusible ions and may bind inorganic ions by electrostatic attraction. Thus ions are absorbed to the surface of roots electrostatically.

Colligative property of a solution is based on the concentration of solute particles but not on its identity. It includes vapor pressure lowering, boiling point elevation, freezing point depression and osmotic pressure. Non-colligative property of a solution is based on the identity of the dissolved particles and the solvent. It includes viscosity, surface tension and solubility.