Blood: a tissue with several transport and defence roles
הוצג| English | משמעות |
|---|---|
| plasma/ˈplæzmə/ | פלזמה |
| platelet/ˈpleɪtlɪt/ | טלטית |
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.
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?
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
Platelets are the cell fragments that trigger clotting at a wound. Red cells have no cell wall, and chloroplasts belong to plants, not plasma.
Match each technical term to its precise meaning.
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
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.
In the lab: 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?
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
Stating the conditions and assumptions lets others repeat the work exactly, and recording the supporting evidence lets them check the conclusion. Hiding disagreeing results removes the evidence that could challenge a wrong conclusion, and one measurement can never establish a wider claim.
Work from known quantities
- 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.
Your turn: A model field contains 76 red cells and 4 white cells. Calculate white cells as a percentage of counted cells.
A model field contains 76 red cells and 4 white cells. Calculate white cells as a percentage of counted cells.
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
The result is 5 %. Known: 76 red cells and 4 white cells counted. Percentage white = 4/(76 + 4) x 100 = 5% of counted cells. A selected field is not a clinical count and omits plasma and platelets.
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.
Not true: Plasma has no transport role because it is not a cell. Plasma is the fluid that carries cells, nutrients, hormones, carbon dioxide and waste around the body. Being a liquid rather than a cell does not remove its transport role.
- Blood consists of plasma with red blood cells, white blood cells and platelets suspended in it.
- A red-cell adaptation explains oxygen transport, not every blood function.
- Watch for: platelets are not whole red blood cells, and plasma is not empty space.
Plasma is the fluid that carries cells, nutrients, hormones, carbon dioxide and waste around the body.
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
True. Plasma is the fluid that carries cells, nutrients, hormones, carbon dioxide and waste around the body. Being a liquid rather than a cell does not remove its transport role.
The liquid blood component carrying dissolved substances: write the technical term.
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
plasma means The liquid blood component carrying dissolved substances.