Blood: a tissue with several transport and defence roles
| English | 中文 | Pinyin |
|---|---|---|
| plasma/ˈplæzmə/ | 血浆 | xuè jiāng |
| platelet/ˈpleɪtlɪt/ | 血小板 | xuè xiǎo bǎn |
What would explain this observation?
- A blood image contains several components, not one cell type. Plasma 血浆 transports dissolved substances while suspended components perform different tasks.
- Start with a prediction. State the quantities or features you would compare, then decide what evidence could distinguish two explanations.
Build the model
- Blood consists of plasma with red blood cells, white blood cells and platelets 血小板 suspended in it. Plasma transports dissolved substances such as carbon dioxide, urea and absorbed nutrients, and distributes heat. Red blood cells carry oxygen using haemoglobin; their biconcave shape increases area, and mature human red cells lack a nucleus, leaving space for haemoglobin. White cells support defence, while platelets contribute to clotting.
- plasma: The liquid blood component carrying dissolved substances; platelet: A blood cell fragment contributing to clotting.
Which component is most directly involved in clot formation?
A red-cell adaptation explains oxygen transport, not every blood function. White cells can engulf pathogens or produce antibodies and antitoxins, developed in infection teaching. Platelets are cell fragments involved in reducing blood loss through clots. Plasma and cells should be identified separately in an image or diagram.
Match each technical term to its precise meaning.
Use the definitions to distinguish related quantities and processes.
Choose evidence that can test it
- A red-cell adaptation explains oxygen transport, not every blood function. White cells can engulf pathogens or produce antibodies and antitoxins, developed in infection teaching. Platelets are cell fragments involved in reducing blood loss through clots. Plasma and cells should be identified separately in an image or diagram.
- Observe prepared images or school-approved slides, rather than collecting students’ blood. Draw distinct components with scale information where available. Evaluate a fictional blood-product proposal using infection-screening evidence, matching and the benefit of replacement; the evaluation concerns supplied data, not personal treatment advice.
Which two habits make the investigation or model in this case more defensible?
Observe prepared images or school-approved slides, rather than collecting students’ blood. Draw distinct components with scale information where available. Evaluate a fictional blood-product proposal using infection-screening evidence, matching and the benefit of replacement; the evaluation concerns supplied data, not personal treatment advice.
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 model image field shows 48 red cells and 2 white cells. White cells are 2/(48+2)×100=4% of the counted cells. This small selected field is not a clinical blood count and excludes plasma and platelets from its denominator.
A model field contains 76 red cells and 4 white cells. Calculate white cells as a percentage of counted cells. Use the same sequence: known quantities → model → relation → substitution → unit and interpretation.
A model field contains 76 red cells and 4 white cells. Calculate white cells as a percentage of counted cells.
The result is 5 %. Known: a model image field shows 48 red cells and 2 white cells. White cells are 2/(48+2)×100=4% of the counted cells. This small selected field is not a clinical blood count and excludes plasma and platelets from its denominator.
Check the conclusion and its limits
- Platelets are not whole red blood cells, and plasma is not empty space. A picture count cannot diagnose health without a validated sampling and measurement system. Red cells transport oxygen; they do not manufacture it in the lungs.
- Return to the original observation. Explain what the result supports, which conditions it assumes, and one way to test a competing explanation.
Plasma has no transport role because it is not a cell. This claim is false: Platelets are not whole red blood cells, and plasma is not empty space. A picture count cannot diagnose health without a validated sampling and measurement system. Red cells transport oxygen; they do not manufacture it in the lungs.
Blood: a tissue with several transport and defence roles: A red-cell adaptation explains oxygen transport, not every blood function. White cells can engulf pathogens or produce antibodies and antitoxins, developed in infection teaching. Platelets are cell fragments involved in reducing blood loss through clots. Plasma and cells should be identified separately in an image or diagram.
Plasma has no transport role because it is not a cell.
Platelets are not whole red blood cells, and plasma is not empty space. A picture count cannot diagnose health without a validated sampling and measurement system. Red cells transport oxygen; they do not manufacture it in the lungs.
The liquid blood component carrying dissolved substances: write the technical term.
plasma means The liquid blood component carrying dissolved substances.