Start here: carbon enters through leaves
Build the basic mechanism before drawing conclusions.
The argument
What this chapter will give you
Follow carbon from leaf to berry and separate sources, transport, sinks, and several ripening clocks.
This is a reading chapter, not a definition enlarged to fill a screen. Its sections build the idea from mechanism and method to the language you can use in front of an actual glass.
Start here: carbon enters through leaves
Photosynthesis uses light energy to turn carbon dioxide and water into sugars. A mature illuminated leaf can make more than it needs and export the surplus: it is a source. A developing berry, growing root or young shoot that imports carbon is a sink. Phloem is the living transport tissue that carries sugars, commonly sucrose, between these organs. Sink strength describes demand and capacity to attract that supply. A young leaf can begin as a sink and later become a source, so these are changing jobs rather than permanent labels.
What is happening
Mature leaves are major carbon sources. Growing shoots, roots, reserves, and fruit act as changing sinks, while phloem moves sucrose through the vine.
Bring it back to the glass
Three checks before the conclusion
- Name the process or growth stage before explaining its consequence.
- Use the worked example to distinguish an observation from its possible cause.
- Identify the missing evidence before applying the explanation to a real bottle.
The language bench
Solid things you can actually say
Use these as sentence shapes, not answers to copy. Replace the details with what your glass can defend.
Start here: carbon enters through leaves
- “Photosynthesis uses light energy to turn carbon dioxide and water into sugars.”
Worked example: sugar rises for more than one reason
- “Imagine berry sugar concentration increasing between two sampling dates.”
What can the explanation support?
- “Harvest sugar supports a potential-alcohol estimate; it cannot by itself prove balanced ripeness, climate, vine health, or quality.”
Make the sentence earn its keep
“That one clue proves the whole story.”
“Harvest sugar supports a potential-alcohol estimate; it cannot by itself prove balanced ripeness, climate, vine health, or quality.”
Keep the mechanism specific and match confidence to the available evidence.
Try it now
A five-minute field exercise
- Is a ripening berry a source or sink?
- Write your answer and its reason before reading the explanation.
- Answer: It is primarily a sink importing carbon for development. Draw light and carbon dioxide entering a mature leaf, sugar travelling through phloem, and arrows to fruit, roots and reserves. Now explain why removing many functioning leaves might change the supply available to several sinks. The result depends on the starting canopy and remaining resources, not leaf count alone.
The line worth keepingHarvest sugar supports a potential-alcohol estimate; it cannot by itself prove balanced ripeness, climate, vine health, or quality.