HORTICULTURE SCIENCE
PLANT BIOLOGY
|
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
|
|
|
It is incorporated into the phloem cells
|
|
|
It is incorporated into the minerals in the phloem
|
|
|
It is incorporated into the sucrose during cellular respiration
|
|
|
It is incorporated into the sucrose during photosynthesis
|
Detailed explanation-1: -Phloem transport is based on high hydrostatic pressure. Thus if the phloem can be punctured, the contents should continue to exude out. If the plant is exposed to radioactively labelled carbon dioxide, the sap can be tested for the presence of the isotopes and the rate of translocation can then be estimated.
Detailed explanation-2: -Translocation occurs in the phloem tissues, which consist of tube-like vessels called phloem vessels. These phloem vessels run from the leaves into every other part of the plant and are responsible for transporting dissolved organic solutes, such as sucrose and amino acids, from the sources to the sinks.
Detailed explanation-3: -Water follows the sugar molecules into the sieve elements through osmosis (since water passively diffuses into regions of higher solute concentration). This water creates turgor pressure in the sieve elements, which forces the sugars and fluids down the phloem tubes toward the sinks.
Detailed explanation-4: -Sucrose transport is favorable for the following reasons: (i) 1 mol sucrose contains more energy than 1 mol of a monosaccharide such as glucose or fructose, thus using the disaccharide is more energy efficient for transport and storage.