Explain nitrate requirements for amino acid synthesis
Connect mineral-ion uptake with protein production.
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 building blocks require the nitrogen supplied by nitrate?
What you will learn
- Connect mineral-ion uptake with protein production.
- Use the stated evidence to explain the method and its limits.
Supply nitrogen rather than carbon food
Nitrate ions provide nitrogen needed to make amino acids. Amino acids are the building blocks of proteins, including many enzymes and structural proteins. A plant can have carbohydrate available and still lack enough nitrogen for normal protein synthesis.
Roots can absorb mineral ions from the soil solution. Nitrate is not the same as the nitrogen gas in air, and ordinary plants should not be described as directly turning atmospheric nitrogen gas into amino acids in their leaves.
Test a mineral requirement fairly
A controlled mineral-solution comparison uses similar seedlings supplied with all required minerals except the ion being investigated. Match light, water, temperature, starting size, growth time and solution handling. A complete-mineral control shows the growth expected under the shared conditions.
Reduced growth in a nitrate-omission treatment is consistent with restricted amino acid and protein production when other conditions are matched. A small plant in an uncontrolled photograph alone does not establish a specific mineral deficiency; many factors can reduce growth.
Sources for this lesson
Pause and explain
Which control best supports a nitrate-omission investigation?
Worked example
Matched seedlings receive a complete mineral solution or one lacking nitrate. The nitrate-omission plants grow less. Explain the supplied result.
Show the worked solution
- Nitrate supplies nitrogen for amino acids.
- Reduced amino acid availability can restrict protein synthesis.
- Use the matched complete-mineral control to connect the treatment and result.
Answer The result is consistent with nitrate shortage restricting amino acid and protein synthesis, limiting growth under these conditions.
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.
Explain why nitrate ions are important for a growing plant.
Give me a hint
Link nitrogen, amino acids and proteins.
Compare my reasoning
- Nitrate supplies nitrogen.
- Nitrogen is needed in amino acids.
- Amino acids build proteins.
Nitrate is needed for amino acid synthesis and hence protein production.
Look for these in your work
- Include amino acids.
- Connect to proteins.
Why might giving extra light fail to restore normal growth in a nitrate-limited seedling?
Give me a hint
One input does not supply another required substance.
Compare my reasoning
- Light supplies energy for photosynthesis.
- It does not supply nitrogen for amino acids.
- Nitrate shortage can still restrict protein synthesis.
Extra light does not replace the nitrate needed for amino acid and protein production.
Look for these in your work
- Separate light and nitrogen roles.
- Retain the limiting resource.
Two nitrate treatments also receive different amounts of water. Why is their growth difference not a clean nitrate-only result?
Give me a hint
Identify the second changed factor.
Compare my reasoning
- Water can affect growth and photosynthesis.
- Both nitrate and water differ.
- Match water supply before assigning the effect to nitrate alone.
Unequal water supply confounds the nitrate comparison; use matched watering and other conditions.
Look for these in your work
- Name water as a confounder.
- Specify a controlled comparison.
Common mistakes
- Nitrate is not the main carbon source for carbohydrate.
- A symptom photograph alone does not diagnose a particular deficiency.
What can you explain now?
Which control best supports a nitrate-omission investigation?
Compare with the explanation
A matched complete-mineral treatment.
It retains the shared conditions while supplying nitrate.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Explain why carbon supply alone cannot meet a plant’s protein-building needs.
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.