Phloem Transport – Flow from Source to Sink
Phloem Transport - Transport of phloem saps from the sugar source to the sugar sink takes place. For the plants specifically angiosperms are observed to having pressure flow hypothesis for their phloem translocation.
Definition of Phloem - Phloem is a complex tissue made up of sieve tubes, sieve cells, phloem parenchyma, and phloem fibres. Among them phloem fibre is the only dead tissue and other are all living.
Phloem Transport - This is a type of transport where food that produce in the Green leaves where transported to different parts of the plants. Phloem transport is bidirectional that means it transported to different direction to send the food in different parts of the plant.
Characteristics of the phloem sap translocation by reassure flow hypothesis -
1. It is just opposite to the direction of xylem flow which occurs from roots to leaves in upward direction and in phloem in different directions.
2. Generally sieve tubes of phloem carries from sugar source to sugar sink.
3. Sugar source indicates the mature leaf or a specific regions plant organ where the photosynthesis takes place. There either photosynthesis produces sugar to that part or it causes dissociation of the starch which stored as extra food to produce sugar.
4. Sugar sink means it is the specific part of the organ of the plant body where the parts absorb sugar or they store the sugar. Such as growing roots, stem tips of the plant.
5. Phloem sap (the food that produce by photosynthesis) flows from the source to the sink as fast as the speed of 1 metre /hour.
6. Phloem sap transport takes place by the process of cytoplasmic streaming or diffusion.
7. Phloem tissue causes flow of fluid due to the bulk pressure which created for the flow of phloem sap from the sugar source to the sugar sink.
8. As sugar concentration increases in the source it increases water potential and allows the water to enter the tube.
9. Due to removal of sugar, concentration is decreases to the sink which decreases water potential and obstacles the water to flow in the tube.
10. The difference in hydrostatic pressure causes the water phloem sap to be transported from the source to the sink.
11. Transport of sugar by the phloem can be divided into three. They are-
(i) Short term Transport - In short term transport sucrose is accumulated in some organs and then transported by the mesophyll tissue to the phloem tube is via two processes – apoplast and symplast.
(ii) Long distance Transport - At the long distance bulk flow of phloem sap occurs as a result of through the sieve tubes from the organs from the phloem source to the phloem sinks.
(iii) Cellular Transport - At the cellular level sucrose is transported by the cell membrane and entered the phloem tissue by means of active transport (this is a type of transport where the molecules move against the concentration gradient by using the pump which use ATP molecules for energy).
You might like these
Means of Transport | Bulk Transport | Passive transport | Diffusion
There are different mechanisms for the transport like diffusion, Osmosis, active transport, facilitated diffusion etc. Mainly we can divide the entire transport process into two those are- active transport and passive transport. Passive transport includes diffusion osmosis
Plant-Water Relations | Water potential|Osmosis|Plasmolysis|Imbibition
This is a physical phenomenon of net flow of solvent molecules from a solution of lower concentration to a solution of higher concentration through a semi permeable membrane (a membrane which allows only the solvent molecules and not the solute molecules
Explain Long Distance Transport of Water | Transport in Plants | Xylem
Transport or conduction of the water means transport of substances from one part of plant to the another means transport of water and dissolved minerals from the roots to the leaves via xylem. Roots the underground parts of the plants which is positive geotrophic in nature.
How do Plant Absorb Water? | Absorption of Water by Roots | Osmosis
As we all know that water is very essential elements for the plants because it acts as an essential raw material for the photosynthesis of plants for their growth and survival of plants need water to carry out many life processes, physiological processes
Water Movement Up a Plant | Absorption of Water by Roots
Transport of water and minerals- The transport of the substances from one part of the plant to another is called conduction. Roots absorbed water and minerals from the soil those are need to be transported to the different parts of the plants body.
Transpiration | Characteristics Features | Different Types | Factors
Definition of transpiration - Transpiration is the physiological activity in which water molecules carried from the root to the pores of the leaves present in the downward side of the leaf and evaporates from the plant body. Actually this is the process of evaporation of
Transpiration and Photosynthesis are Compromise |Transpiration Process
Photosynthesis is a biochemical process by which green plants make their own food in presence of water, carbon dioxide, sunlight is called photosynthesis. This is the process where chemical energy is stored in the glucose and later it is released as energy for performing
Uptake of Transport Nutrients | Definition of Osmosis | Absorption
The transport of substances from one part of the plant to the another part is called conduction. In this process water is transported to the Green Leaves for photosynthesis, takes place and the food produced in the leaves are transported to different parts of the plant.
The Pressure Flow or Mass Flow Hypothesis | Mechanism |Turgor Pressure
It is the hypothesis by which transport of sap by phloem can be best described. This hypothesis was given by Ernst Munch in 1930 who was an German plant physiologist. According to this hypothesis a high concentration of organic substances like sugar, inside the phloem
Electron Transport System and Oxidative Phosphorylation | ETC |Diagram
It is also called ETC. Electron transfer means the process where one electron relocates from one atom to the other atom. Definition of electron transport chain - The biological process where a chains of redox reaction take place as electrons are transferred from the
From Phloem Transport – Flow from Source to Sink to HOME PAGE
Recent Articles
-
Respiratory Volumes and Capacities | Tidal Volume | Dead Space
Aug 29, 25 05:17 PM
Explain respiratory volumes and capacities: Tidal Volume - Tidal volume is the volume of air inspired or expired in relaxed or resting position. Amount of tidal volume is about 500 m and it consists o… -
Mechanism of Breathing | Definition of Inspiration and Expiration
Aug 17, 25 11:41 PM
Breathing is the process which is accomplished in three states that is inspiration expiration and pause . Definition of inspiration - Entry of air into the lungs from outside during breathing is calle… -
Human Respiratory System | External Nares | Nasal Cavity | Pharynx
Aug 04, 25 03:14 PM
Definition of respiration - This is the process of making energy available to organisms and their living cells through enzyme controlled catabolic breakdown of organic molecules. The organic materials… -
Disorders of Digestive System | Symptoms of Jaundice | Vomiting |
Jul 16, 25 12:18 PM
Jaundice- It is a disease that occurs due to Umesh discoloration of the skin due to deposition of bilirubin and biliverdin pigment. Jaundice can be offered according to the different position like pre… -
Absorption of Digested Products | Absorption of Water | Nephrons
Jul 09, 25 02:24 PM
Food and water is observed in different parts of the body and is distributed in different cells and tissues. Absorption of food is observed to be observed in the small intestine in the specific type o…
New! Comments
Have your say about what you just read! Leave me a comment in the box below.