BRAINCAKEPhloem Loading
Active phloem loading uses the apoplast pathway and uses energy and membrane-bound co-transporter protein and a proton pump to move sucrose into the sieve tubes.
Passive phloem loading transports sucrose freely through plasmodesma in the symplast pathway.
Apoplast Pathway
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Key terms in this lesson
- ATP
- Adenosine triphosphate, a nucleotide that acts as the immediate energy source in cells, releasing energy when hydrolysed to ADP and phosphate.
- diffusion
- The net passive movement of molecules or ions from a region of higher concentration to a region of lower concentration, down a concentration gradient.
- facilitated diffusion
- The passive movement of molecules or ions down their concentration gradient through protein channels or carrier proteins.
- co-transport
- The movement of one molecule or ion across a membrane, using a carrier protein, coupled to the facilitated diffusion of another down its concentration gradient.
- phloem
- Plant vascular tissue, made of sieve tube elements and companion cells, that transports organic solutes such as sucrose around the plant.
More in Mass Transport in Plants
- Movement of Water Up the Stem
- Movement of Water Across the Leaf
- Movement of Water Through the Stomata
- Translocation
- Mass Flow through Sieve Tube Elements
- Mass Flow Model
- Phloem Unloading
- Ringing Experiments
All 15 lessons in Mass Transport in Plants · All AQA AS-level Biology topics