Where the glucose goes
| English | Français |
|---|---|
| starch/stɑːtʃ/ | starch |
| cellulose/ˈseljuːləʊs/ | cellulose |
| nitrate ion/ˈnaɪtreɪt ˈaɪɒn/ | nitrate ion |
What would explain this observation?
- A leaf makes glucose, but a growing plant also needs strong walls, stored material and proteins. Glucose can supply carbon to several products with different functions.
- Start with a prediction. State the quantities or features you would compare, then decide what evidence could distinguish two explanations.
Build the model
- Glucose made by photosynthesis can be used in respiration. It can be converted into insoluble starch 淀粉 for storage or into fat or oil for storage. It can also be used to make cellulose 纤维素, which strengthens cell walls. Plants use glucose and nitrate ions 硝酸根离子 absorbed from soil to form amino acids; these are used to synthesize proteins.
- cellulose: A carbohydrate that strengthens plant cell walls; starch: An insoluble carbohydrate used for storage in plants; nitrate ion: A mineral ion supplying nitrogen for plant amino-acid and protein formation.
Why are nitrate ions needed alongside glucose for plant protein production?
Storage, structure and energy transfer are separate roles. Starch is insoluble, so it can be stored without behaving like an equivalent amount of dissolved glucose. Cellulose is structural. Nitrate supplies needed nitrogen for amino acids; sunlight alone does not supply every element a growing plant needs.
Match each technical term to its precise meaning.
Use the definitions to distinguish related quantities and processes.
Choose evidence that can test it
- Storage, structure and energy transfer are separate roles. Starch is insoluble, so it can be stored without behaving like an equivalent amount of dissolved glucose. Cellulose is structural. Nitrate supplies needed nitrogen for amino acids; sunlight alone does not supply every element a growing plant needs.
- Sort glucose-use cards by product and function. Link nitrate absorption by roots to protein production rather than to oxygen release. Interpret teacher-provided results of starch, glucose and protein tests with controls. Actual testing follows approved reagents, heating and disposal; a negative test concerns the stated sample and detection conditions.
Which two habits make the investigation or model in this case more defensible?
Sort glucose-use cards by product and function. Link nitrate absorption by roots to protein production rather than to oxygen release. Interpret teacher-provided results of starch, glucose and protein tests with controls. Actual testing follows approved reagents, heating and disposal; a negative test concerns the stated sample and detection conditions.
Work from known quantities
- State the known values and their units. Choose the relation because its assumptions fit this case, then rearrange before substitution.
- Known: a fictional allocation model has 100 carbon units from glucose. It assigns 35 to respiration, 25 to starch, 20 to cellulose and 10 to oils. The remaining 10 can be assigned to other products in this model. These are accounting units, not a fixed biological percentage or a balanced synthesis equation.
A fictional 80-unit allocation assigns 24 units to storage. Calculate the storage percentage. Use the same sequence: known quantities → model → relation → substitution → unit and interpretation.
A fictional 80-unit allocation assigns 24 units to storage. Calculate the storage percentage.
The result is 30 %. Known: a fictional allocation model has 100 carbon units from glucose. It assigns 35 to respiration, 25 to starch, 20 to cellulose and 10 to oils. The remaining 10 can be assigned to other products in this model. These are accounting units, not a fixed biological percentage or a balanced synthesis equation.
Check the conclusion and its limits
- Photosynthesis makes glucose rather than directly making every protein. Plants need mineral nutrients as well as light, water and carbon dioxide. A glucose molecule cannot supply nitrogen that it does not contain; nitrate is relevant to amino acids and proteins.
- Return to the original observation. Explain what the result supports, which conditions it assumes, and one way to test a competing explanation.
Sunlight supplies every element needed to make proteins. This claim is false: Photosynthesis makes glucose rather than directly making every protein. Plants need mineral nutrients as well as light, water and carbon dioxide. A glucose molecule cannot supply nitrogen that it does not contain; nitrate is relevant to amino acids and proteins.
Where the glucose goes: Storage, structure and energy transfer are separate roles. Starch is insoluble, so it can be stored without behaving like an equivalent amount of dissolved glucose. Cellulose is structural. Nitrate supplies needed nitrogen for amino acids; sunlight alone does not supply every element a growing plant needs.
Sunlight supplies every element needed to make proteins.
Photosynthesis makes glucose rather than directly making every protein. Plants need mineral nutrients as well as light, water and carbon dioxide. A glucose molecule cannot supply nitrogen that it does not contain; nitrate is relevant to amino acids and proteins.
A carbohydrate that strengthens plant cell walls: write the technical term.
cellulose means A carbohydrate that strengthens plant cell walls.