These are authored teaching summaries and invented diagrams in words, not microscopy images or laboratory observations. Function statements were checked against the official QCAA Topic 1 list and the government cell sources in the ledger. Read a model's completeness label before classifying it. An organelle's presence in a typical teaching diagram is not a universal rule for every specialised cell.
Card A · features shared across cells
The standard living-cell models compared here share a plasma membrane separating inside from outside, cytoplasm, DNA and ribosomes that assemble proteins. Some specialised mature cells differ from canonical diagrams, including mature mammalian red blood cells, which lack a nucleus; this is a comparison rule for the modelled cells, not a universal checklist for every mature cell. Ribosomes are cell structures but not membrane-bound. Cell walls are not a safe single test for prokaryote versus eukaryote: several different groups can have them. A drawing may omit a structure to stay readable; an omission in an incomplete drawing is not evidence of biological absence.
Card B · two organisation patterns
Prokaryotic cells, including bacteria and archaea, lack a membrane-bound nucleus. Their DNA occupies a nucleoid region; they still have ribosomes, cytoplasm and a plasma membrane. Eukaryotic lineages have a membrane-bound nucleus and other internal membrane-bound compartments in typical cells; some specialised mature cells are exceptions. Plants, animals and fungi are eukaryotes. Do not decide “prokaryote” merely because a faint or simplified image did not label a nucleus. A complete inventory or stronger observation is needed.
Card C · nine named structures, one useful job each
| Structure | Carefully bounded job for these lessons |
|---|---|
| Nucleus | Membrane-bound compartment containing most of a typical eukaryotic cell's DNA. |
| Ribosomes | Assemble proteins; free in cytoplasm or attached to rough ER. Not membrane-bound themselves. |
| Mitochondria | In many eukaryotic cells, carry out steps of aerobic respiration that make ATP available; not a food-making machine. |
| Rough ER | Ribosome-studded membrane network involved in making/processing many proteins destined for membranes or secretion. |
| Smooth ER | Membrane network involved in lipid synthesis and other functions that vary by cell. No surface ribosomes. |
| Golgi apparatus | Modifies, sorts and packages many products from the ER. |
| Lysosomes | In many animal-cell models, membrane compartments that break down and recycle material. Plant cells can use lytic vacuoles for related work; do not say plants universally lack recycling. |
| Vacuoles | Membrane compartments with varied jobs; a large central vacuole in many plant cells helps water balance. Animal cells can also have smaller vacuoles. |
| Chloroplasts | In photosynthetic plant cells, organelles where photosynthesis takes place. Not every plant cell has chloroplasts. |
One route, not every protein: In an illustrative secretory cell, a protein made by a ribosome attached to rough ER can pass through ER processing and Golgi sorting before leaving the cell. Other proteins follow other routes; the diagram is not a complete transport account.
Card D · four invented schematic inventories
- Pond bacterium model — comparison features fully stated: plasma membrane, cytoplasm, DNA in a nucleoid region, ribosomes; no membrane-bound nucleus or mitochondria. It is a fictional schematic, not a cultured organism. The list does not claim to enumerate every real cellular feature.
- Leaf mesophyll model — comparison features fully stated: plasma membrane, cytoplasm, DNA including in a membrane-bound nucleus, ribosomes, mitochondria, chloroplasts and a large central vacuole. It illustrates one photosynthetic eukaryotic cell type, not every cell in a leaf; the list is not exhaustive.
- Human intestinal lining model — comparison features fully stated: plasma membrane, cytoplasm, DNA including in a membrane-bound nucleus, ribosomes, mitochondria, rough ER, smooth ER and Golgi apparatus. Other structures have not been inventoried. No diagnosis, real tissue image or actual organelle count is implied.
- Unfinished sketch — INCOMPLETE: plasma membrane and ribosomes are labelled; the rest of the drawing has been left blank. Classification is undetermined from this sketch. The blank space is not a negative observation.
Card E · organisation grows beyond a cell
One intestinal epithelial cell can be considered as part of epithelial tissue contributing to the small intestine, an organ in the digestive system. The small intestine contains several tissues; one epithelial cell or tissue does not by itself make the whole organ. Similarly, a cardiac muscle cell belongs to cardiac muscle tissue within the heart, one organ of the circulatory system. The hierarchy explains a contribution, not a claim that all cells in an organ are identical. A plant example can be built locally after checking its tissue and system terms.
Card F · how to read a model honestly
Use stated feature → supported comparison → model limit. A complete comparison inventory can support presence/absence for the named features within that invented card; it does not establish all properties of a real species. An incomplete sketch supports only the labels it shows. None of these cards reports measurements, organelle counts, an experiment or a clinical finding.
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