Week 1: Cells, Organisation & Biological Molecules

Viruses are not living organisms. They are smaller than bacteria, have no cellular structure, consist of a protein coat surrounding either DNA or RNA, and can only reproduce inside living cells. You must know the term pathogen (an organism that causes disease) and understand that pathogens can be fungi, bacteria, protoctists or viruses. The spec requires you to know specific named examples of each.

1. Virus diagram (10 min): Sketch a generalised virus structure from memory. Label: protein coat, nucleic acid (DNA or RNA). Add a note explaining why viruses are described as parasitic. Then check your diagram against your textbook/notes.
2. Pathogen fact files (25 min): Create a one-page fact file for each of these pathogens. For each, include: type of organism, what disease it causes, how it is transmitted, and one key feature from the specification.
   • Tobacco mosaic virus (TMV): Prevents chloroplast formation → discoloured leaves
   • Influenza virus: Causes flu
   • HIV: Causes AIDS
   • Plasmodium (protoctist): Causes malaria
   • Pneumococcus (bacterium): Causes pneumonia; spherical shape
   • Lactobacillus bulgaricus (bacterium): Used in yoghurt production; rod-shaped
3. Dual coding exercise (10 min): For each pathogen, draw a simple sketch alongside your notes. For example, draw TMV with a note about leaf discolouration, or draw a mosquito next to Plasmodium. Visual association strengthens recall.
4. Quick retrieval (5 min): Close your fact files. On a blank sheet, list as many pathogen names, diseases and organism types as you can. Check and correct.

• I can describe the basic structure of a virus (protein coat + DNA or RNA)
• I can explain why viruses are not considered living
• I can define "pathogen" and give examples from all four groups
• I know what disease each named pathogen causes
• I can describe what TMV does to tobacco plant leaves and why

You need to describe the structure and function of seven cell components: nucleus, cytoplasm, cell membrane, cell wall, mitochondria, chloroplasts, ribosomes, and vacuole. You also need to know which of these are found in plant cells only (cell wall, chloroplasts, large permanent vacuole) versus those shared with animal cells. The concept of levels of organisation (organelle → cell → tissue → organ → organ system) connects everything together.

1. Blank cell diagrams (15 min): On a blank sheet, draw a labelled animal cell and a labelled plant cell side by side, entirely from memory. Include all seven organelles where appropriate. After you finish, check against your textbook and add anything you missed in a different colour.
2. Function flashcards (15 min): Make a flashcard for each organelle. On the front: the organelle name. On the back: its function in one clear sentence. Here is the level of precision you need:
   • Nucleus: Contains genetic material (DNA); controls cell activities
   • Cytoplasm: Jelly-like substance where most chemical reactions take place
   • Cell membrane: Controls what enters and leaves the cell
   • Cell wall: Made of cellulose; provides support and shape (plants only)
   • Mitochondria: Site of aerobic respiration; releases energy (ATP)
   • Chloroplasts: Contain chlorophyll; site of photosynthesis (plants only)
   • Ribosomes: Site of protein synthesis
   • Vacuole: Contains cell sap; maintains turgor pressure (large & permanent in plant cells)
3. Comparison table (10 min): Draw a table comparing plant and animal cells. Columns: Feature | Plant Cell | Animal Cell. Rows: cell wall, chloroplasts, vacuole, cell membrane, nucleus, cytoplasm, mitochondria, ribosomes. Tick/cross or add detail for each.
4. Levels of organisation (5 min): Write the hierarchy from memory: organelle → cell → tissue → organ → organ system → organism. Give one named example at each level (e.g. mitochondrion → muscle cell → muscle tissue → heart → circulatory system → human).
5. Spaced repetition (5 min): Go back to yesterday's pathogen fact files and test yourself on 3 quick questions without looking. This combats the forgetting curve.

• I can draw and label both plant and animal cells from memory
• I can state the function of all 7 organelles
• I can list 3 differences between plant and animal cells
• I can order the levels of organisation with an example at each level

There are three main biological molecules: carbohydrates (contain C, H, O), proteins (contain C, H, O, N — and sometimes S), and lipids (contain C, H, O). Each is a large molecule built from smaller units: starch/glycogen from simple sugars, proteins from amino acids, lipids from fatty acids and glycerol. You also need to describe the practical food tests for glucose, starch, protein and fat.

1. Molecule summary mind map (15 min): In the centre write "Biological Molecules". Branch out to carbohydrates, proteins and lipids. For each, add: elements present, monomer (building block), polymer examples, and where they are found. Use colour coding — one colour per molecule type.
2. Food tests table (15 min): Create a table with columns: Nutrient Tested | Reagent/Method | Method Steps | Positive Result. Fill in from memory for:
   • Glucose (reducing sugar): Benedict's reagent → heat in water bath → turns from blue to brick-red/orange
   • Starch: Iodine solution → turns from brown/yellow to blue-black
   • Protein: Biuret reagent (NaOH + CuSO₄) → turns from blue to purple/lilac
   • Lipid (fat): Ethanol emulsion test → mix with ethanol, pour into water → white cloudy emulsion forms
3. Elaborative interrogation (10 min): For each food test, ask yourself "Why does this work?" and "What would happen if...?" For example:
   • Why must the Benedict's test be heated? (The reaction requires energy to proceed)
   • What would the result be if the sample contained starch but no glucose? (Positive for iodine, negative for Benedict's)
   • Why must the ethanol emulsion test use ethanol first? (Lipids dissolve in ethanol but not water — when poured into water, they come out of solution as tiny droplets)
4. Quick retrieval from earlier days (5 min): Without looking back, write down: 3 features of bacteria, 2 named protoctists, the function of ribosomes.

• I can name the elements in carbohydrates, proteins and lipids
• I can state the monomers for starch/glycogen, proteins and lipids
• I can describe all four food tests including reagent, method and colour change
• I can explain why the Benedict's test requires heating

Enzymes are biological catalysts that speed up metabolic reactions without being used up. Each enzyme has a specific active site that is complementary in shape to its substrate (lock and key model). Temperature and pH both affect enzyme function: increasing temperature increases rate up to the optimum, but above this the enzyme denatures (the active site changes shape permanently). Changes in pH away from the optimum also alter the active site shape.

1. Key definitions (5 min): Write from memory: enzyme, biological catalyst, active site, substrate, denaturation, optimum temperature. Check and correct.
2. Graph sketching (15 min): On graph paper or plain paper, sketch these two graphs from memory:
   • Rate of reaction vs temperature: Rate increases, peaks at optimum (~37°C for human enzymes), then drops sharply as enzyme denatures. Label the optimum and explain why the curve falls.
   • Rate of reaction vs pH: Bell-shaped curve peaking at the optimum pH. Label the optimum and add a note that different enzymes have different optimum pH values (e.g. pepsin in stomach = pH 2, amylase in mouth = pH 7).
3. Self-explanation exercise (15 min): Explain each of the following out loud or in writing as if you are teaching a Year 7 student. If you can explain it simply, you understand it:
   • Why does increasing temperature (below the optimum) increase the rate of enzyme activity?
   • What happens to the active site above the optimum temperature? Why can't the substrate fit anymore?
   • Why is denaturation permanent? (The bonds holding the active site shape break and cannot reform)
   • Why do enzymes only work on one type of substrate?
4. Past paper practice (15 min): Complete at least 3 enzyme questions from the resources below. Mark them yourself and note any errors.

• I can define enzyme, active site, substrate, denaturation
• I can sketch and explain the rate vs temperature graph
• I can sketch and explain the rate vs pH graph
• I can explain why enzymes are specific to their substrate
• I can structure a 6-mark answer on temperature and enzyme activity

Saturday is your consolidation day. No new content — today is about testing everything you've covered this week under more realistic conditions, identifying your remaining gaps, and planning what needs more attention in the coming weeks.

1. Full retrieval grid (15 min): Create a blank grid with these column headings across the top: Organism groups, Cell structure, Levels of organisation, Biological molecules, Food tests, Enzymes. Down the side, write prompts like: "Name 2 examples", "Key feature", "Definition of...", "Draw a diagram of...". Fill in the entire grid without any notes. This is your honest baseline.
2. Mark and traffic-light your grid (5 min): Check your grid against this week's notes. Use three colours:
   • 🟢 Green: Confident — I could answer this in an exam
   • 🟠 Amber: Partially correct — I need to revisit this
   • 🔴 Red: Couldn't recall — this needs urgent re-revision
3. Re-revise red/amber areas (10 min): Go back to the specific day's tasks for any red or amber topics. Re-read the key facts, then test yourself again immediately.
4. Timed mini-test (20 min): Attempt the questions below under timed, exam-like conditions. No notes, no phone, strict time. Write full answers as you would in an exam.
   1. State the eight characteristics shared by all living organisms. (4 marks)
   2. Describe three differences between plant cells and animal cells. (3 marks)
   3. A student tested a food sample with Benedict's reagent and the solution remained blue. They then tested it with iodine solution and the solution turned blue-black. What conclusions can you draw about the food sample? (3 marks)
   4. Explain the effect of increasing temperature on the rate of an enzyme-controlled reaction. (6 marks)
   5. Describe the features of viruses and explain why they are not classified as living organisms. (4 marks)
5. Self-mark (5 min): Mark your mini-test using the specification as your mark scheme. Be honest and strict — in the real exam, vague answers don't score.

• I can list all 8 life characteristics and explain each briefly
• I can classify organisms into the 5 groups with key features and examples
• I can explain what pathogens are and give named examples
• I can describe virus structure and explain why they are not living
• I can draw and label plant and animal cells with all organelles
• I can state the function of every cell component in the spec
• I can order the levels of biological organisation
• I can name the elements in carbohydrates, proteins and lipids
• I can describe all four food tests with full method and colour changes
• I can explain how temperature and pH affect enzyme activity
• I can define denaturation and explain it in terms of active site shape