Trace carbohydrate through respiration transport and nectar
Link three further uses of photosynthetic carbohydrate.
Section B6.1 · Photosynthesis
Exam scope and assessment notes
Mapped to the named 0973 section using teaching from the corresponding single-science course. A 0973-specific review of every Core and Supplement objective is still in progress. Written practice is self-checked; it does not demonstrate supervised laboratory competence or award an official Cambridge grade. This qualification reports two grades on the 9–1 scale; confirm the entry route for your zone and exam series.
Before you begin
- Recall chloroplasts, enzymes and the difference between photosynthesis and respiration.
- Use the stated observations, quantities and controls; diagrams are schematic.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Which tissue transports sucrose in this syllabus model?
What you will learn
- Link three further uses of photosynthetic carbohydrate.
- Use the stated evidence to explain the method and its limits.
Use and distribute carbohydrate
Glucose can be used in respiration to release energy for cell activities. Respiration is a series of chemical reactions in cells, not simply gas exchange at the leaf surface. Plants respire in both light and dark.
Carbohydrate can be converted into sucrose for transport in the phloem. Transport allows non-photosynthesising tissues and growing or storing parts to receive an organic nutrient supply. Do not assign the named sucrose-transport role to xylem.
Support reproduction
Sugar can be supplied in nectar, helping attract insects that may pollinate flowers. Nectar is not pollen: an insect visiting a flower for nectar can also transfer pollen between the relevant flower structures.
Nectar production, transport, respiration, starch storage and cellulose construction are different uses of a shared carbohydrate supply. A plant need not use every glucose molecule in all five ways, and a diagram arrow represents allocation, not duplication of matter.
Sources for this lesson
Pause and explain
How can nectar support pollination?
Worked example
Connect three destinations: energy for active transport, sugar moving from a leaf, and a reward attracting insect visitors.
Show the worked solution
- Use glucose in respiration for energy release.
- Use sucrose transport in phloem.
- Use nectar for insect attraction in pollination.
Answer Respiration releases energy; sucrose travels in phloem; nectar attracts potential insect pollinators.
Try a topic test
Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.
Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
State the use of glucose in respiration.
Give me a hint
Focus on energy release for cell activity.
Compare my reasoning
- Glucose is a nutrient substrate.
- Respiration releases energy for metabolism.
Glucose is used in respiration to provide energy for cell activities.
Look for these in your work
- Use respiration.
- Explain energy release.
Name the transported sugar, its tissue and one non-photosynthesising destination.
Give me a hint
Follow the leaf-to-root example.
Compare my reasoning
- Name sucrose.
- Name phloem.
- A root is a suitable destination.
Sucrose is transported in phloem, for example from a photosynthesising leaf to a root.
Look for these in your work
- Correct sugar and tissue.
- Give a plausible destination.
A flower secretes sugary nectar. Explain a benefit to the plant that is not simply “the flower eats the nectar”.
Give me a hint
Link insect behaviour to reproduction.
Compare my reasoning
- Nectar can attract insects.
- Visiting insects can carry pollen.
- Pollen transfer can support pollination.
Nectar can attract insects whose visits help transfer pollen for pollination.
Look for these in your work
- Connect attraction and pollen transfer.
- Keep nectar distinct from pollen.
Common mistakes
- Nectar is not the same material as pollen.
- Xylem is not the named sucrose-transport tissue.
What can you explain now?
How can nectar support pollination?
Compare with the explanation
It attracts insects that may transfer pollen.
The reward and pollen transfer are related but distinct.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Retrieve all five required carbohydrate uses, including starch and cellulose.
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.