--- title: "Is everything alive made of cells?" subtitle: "Year 8 Biology · Cells · Lesson 2" --- # Is everything alive made of cells? **Name:** {{field-24}} **Date:** {{field-15}} **Class:** {{field-15}} > **Key question:** A gum tree, a mushroom, the bacteria in yoghurt and you. One thing they share that a rock, a cloud and a robot don't. :::teacher-note **In one sentence:** Students state cell theory, explicitly including plants, fungi and single-celled organisms, and distinguish single-celled from multicellular organisms (AC9S8U01, node 2, a hinge node). **Students should be able to say:** I can state cell theory. I can explain that plants, fungi and bacteria are made of cells too. I can give examples of single-celled and multicellular organisms. **Width:** the unmarked parts are the floor every student does (Engage, Explore, Explain, Evaluate). Typical and Wider sections add contexts, not difficulty. Students work in the online tutorial alongside this sheet. ::: ## Engage :::keep-together **Which of these are made of cells?** ☐ Animals and plants ☐ Only things you can see moving ☐ Animals, plants, fungi and bacteria: every living thing ☐ Only animals My prediction, and why: {{lines-3}} ::: :::teacher-note **What happens:** Every living thing: animals, plants, fungi and bacteria. A bacterium is a single cell; you are trillions of cells. ::: ## Explore Try it on the board in the tutorial. Was your prediction right? What was different? {{lines-2}} ## Explain: cell theory :::keep-together ### Cell theory **Which statement is cell theory?** ☐ Big organisms have big cells ☐ All living things are made of one or more cells, and the cell is the smallest unit of life ☐ Cells are found in living and non-living things ☐ Only animals are made of cells ::: :::teacher-note **Answer:** All living things are made of one or more cells, and the cell is the smallest unit of life ::: :::keep-together ### One or many **Single-celled or multicellular?** Groups: Single-celled, Multicellular - Bacteria in yoghurt: {{field-15}} - Yeast: {{field-15}} - A gum tree: {{field-15}} - A mushroom: {{field-15}} - An amoeba: {{field-15}} - You: {{field-15}} ::: :::teacher-note **Answer:** Bacteria in yoghurt → Single-celled; Yeast → Single-celled; A gum tree → Multicellular; A mushroom → Multicellular; An amoeba → Single-celled; You → Multicellular ::: :::keep-together ### Doing everything **A single-celled yeast cell and one of your skin cells are both cells. What's the big difference?** ☐ The yeast cell does everything to stay alive on its own; your skin cell is one of trillions, each doing a job ☐ Your skin cell has no membrane ☐ The yeast cell isn't really alive ::: :::teacher-note **Answer:** The yeast cell does everything to stay alive on its own; your skin cell is one of trillions, each doing a job ::: :::typical ## Elaborate: is it alive? :::keep-together **Made of cells (living, or once living) or not?** Groups: Made of cells, Not made of cells - A slice of bread: {{field-15}} - A wooden table: {{field-15}} - A pebble: {{field-15}} - A cotton T-shirt: {{field-15}} - Plastic: {{field-15}} ::: :::teacher-note **Answer:** A slice of bread → Made of cells; A wooden table → Made of cells; A pebble → Not made of cells; A cotton T-shirt → Made of cells; Plastic → Not made of cells ::: ::: :::wider ## Elaborate: the smallest living thing :::keep-together **A virus is far smaller than a bacterium. It has DNA (or RNA) in a protein coat, but no membrane or cytoplasm of its own, and it can only reproduce inside a living cell. Using cell theory, is a virus a living thing?** ☐ Yes: it has DNA ☐ Yes: it is very small ☐ By cell theory, no: it isn't a cell, so scientists usually call it non-living ::: :::teacher-note **Answer:** By cell theory, no: it isn't a cell, so scientists usually call it non-living Viruses sit on the boundary. Most biologists say they are not alive, because they are not cells. ::: ::: ## Evaluate: look back Write one sentence: "At first I thought… Now I think… because…" **Revision summary** - **Cell theory:** all living things are made of one or more cells; the cell is the smallest unit of life; cells come from other cells. - That includes **plants, fungi and bacteria**, not only animals. - **Single-celled** organisms (bacteria, yeast) are one cell doing everything; **multicellular** organisms are many cells working together. ## Exit ticket :::keep-together **Name a single-celled organism and a multicellular one that isn't an animal.** {{lines-3}} ::: :::teacher-note **Answer:** For example: a bacterium (single-celled) and a gum tree or mushroom (multicellular). :::