Cells and Living Systems
MYP Sciences Framework — Unit: Cells and Living Systems (Year 2)
Every organism on the planet, from a single bacterium to a blue whale, is built from the same basic unit: the cell. This unit is about zooming in and out — from whole organisms down to organelles, and back out again — and learning to explain WHY structure matches job at every level. Examiners rarely just want a labelled diagram; they want you to say what a structure does and why it's shaped that way.
Overview — The Shape of the Topic
Living systems are organised in a hierarchy — cells group into tissues, tissues into organs, organs into systems, and systems into a whole organism. Each step up adds cooperation, not just size: a tissue can do things a single cell cannot, because many cells are working together toward one job. Cells themselves come in specialised shapes matched to their function (a nerve cell looks nothing like a muscle cell because they do completely different jobs), and all of this is only visible because of microscopes, which let us see structures far smaller than the human eye can resolve.
- Cell theory underpins everything here: all living things are made of cells, the cell is the basic unit of life, and new cells come only from existing cells dividing.
- Plant and animal cells share core organelles but plant cells carry three extra structures (wall, chloroplast, large vacuole) tied to their fixed, photosynthetic lifestyle.
- Unicellular organisms cram every life function into one cell; multicellular organisms spread the workload across specialised, cooperating cells.
- Magnification calculations and microscope labelling are the most common 'lost mark' zone — precision with units and structure names matters more than memorising a diagram.
The shape of the chapter
Command terms you'll actually be marked against
| Command term | What it demands | AO | Mark-earning move |
|---|---|---|---|
| State | Give a specific name, value or answer with no explanation required. | Knowing & Understanding | 1 mark for the correct word/order — adding explanation earns nothing extra and wastes exam time. |
| Identify | Pick out and name one specific feature from a diagram, data set or scenario. | Knowing & Understanding | The mark is for the correct NAME — a vague description without naming the structure scores zero. |
| Describe | Give a detailed account — structure AND what it does/looks like, more than a single word. | Knowing & Understanding | Needs at least two linked points (structure + resulting function) to get full marks. |
| Explain | Give reasons or cause-and-effect — say WHY or HOW, not just WHAT. | Knowing & Understanding / Processing | Losing the 'because / so that' link is the #1 way students drop this mark even with correct facts. |
| Distinguish | State the difference between two things, not just describe each on its own. | Knowing & Understanding | Describing A then B in isolation, with no direct contrast, scores lower than one sentence that compares them directly. |
| Suggest | Apply knowledge to a new or unfamiliar situation using logical reasoning. | Processing & Evaluating | More than one answer can be accepted — the reasoning chain is marked, not a single 'correct' fact. |
Key point
Overview