KS3 Animal Academy

Animal cells have several key parts: the nucleus (control centre, holds DNA), cytoplasm (jelly where chemical reactions happen), cell membrane (controls what enters and leaves), and mitochondria (where energy is released). Plant cells also have a cell wall, chloroplasts and a vacuole — but animal cells don’t. The key question to ask: what does each part DO? Every structure has a function. Learn these functions and you’ll answer most cell biology questions.

An ecosystem is all the living things in an area plus their environment. Energy flows through ecosystems via food chains and food webs. A producer (like grass or a plant) captures energy from the sun. Primary consumers (herbivores like rabbits) eat producers. Secondary consumers (carnivores like foxes) eat primary consumers. Decomposers (fungi, bacteria) break down dead material. The key word is ENERGY — it always flows from sun → producer → consumer.

DNA stands for Deoxyribonucleic Acid. It’s found in the nucleus of every cell. DNA is shaped like a twisted ladder (double helix). A gene is a section of DNA that codes for a specific feature (like eye colour). We inherit genes from both parents — one copy from mum, one from dad. Dominant alleles always show their effect; recessive alleles only show when you have two copies. This is why two brown-eyed parents can have a blue-eyed child.

Natural selection is how species change over time. Charles Darwin discovered it in 1859. The process: (1) Within any species, individuals vary slightly. (2) Some variations help survival — like a hedgehog with longer spines is better protected. (3) Those individuals survive longer and reproduce more. (4) They pass on the helpful variation to offspring. Over millions of years, small changes add up to produce new species. This is evolution. The key phrase: ‘survival of the fittest’ means best suited to the environment, not strongest.

The human body has several interconnected systems. The circulatory system pumps blood (heart, blood vessels). The digestive system breaks down food (stomach, intestines). The respiratory system gets oxygen in and CO₂ out (lungs). The nervous system sends signals (brain, nerves). The skeletal system provides structure and protects organs (bones). The muscular system creates movement (muscles). Remember: each system has organs that work together for one job.

Scientists follow a standard method to investigate the world. The steps are: (1) Observation — notice something interesting. (2) Question — what do you want to find out? (3) Hypothesis — make a prediction you can test. (4) Experiment — design a fair test. (5) Results — collect and record data. (6) Conclusion — what do the results show? Was your hypothesis right? The key to a good experiment is making it FAIR — only change one variable at a time.

Writers choose words and techniques deliberately to create effects on the reader. The main techniques at KS3: Simile (comparing using ‘like’ or ‘as’: “as quiet as a mouse”). Metaphor (saying something IS something else: “he was a lion in battle”). Personification (giving human qualities to non-human things). Alliteration (repeated sounds: “Peter Piper picked...”). Onomatopoeia (words that sound like what they describe: buzz, crash). Rhetorical question (a question for effect, not answer). The key is always to explain the EFFECT — why did the writer choose this?

Persuasive writing aims to change the reader’s mind or get them to do something. Use the AFOREST structure: Alliteration (makes it memorable), Facts (evidence), Opinions (your view, stated confidently), Rhetorical questions (makes the reader think), Emotional language (appeal to feelings), Statistics (numbers as proof), Three/triples (rule of three for emphasis). Start with a powerful hook. Use connectives (Furthermore, However, In conclusion). End with a call to action. Strong persuasive writing sounds confident — no “I think maybe...”

Analysing poetry means explaining HOW the poet creates effects, not just WHAT the poem is about. Look at: Form (sonnet? free verse? how many stanzas?), Structure (how is it organised? does the mood change?), Language (what techniques are used — metaphor, simile, personification?), Tone (what is the poet’s attitude?). For each technique you spot, ask: what EFFECT does this have on the reader? Use the PEE structure: Point, Evidence (quote), Effect.

When answering comprehension questions: (1) Read the passage carefully — at least twice. (2) Underline or note key information. (3) Read the question — what exactly is it asking? (4) Find evidence in the text. (5) Write a clear answer using words from the question. For inference questions (what does the text suggest?), find clues in the language. For analysis questions, quote directly from the text and explain the effect.

A formal letter has a strict structure: Your address (top right) → Date → Recipient’s address (left) → Dear Sir/Madam (or name) → Opening paragraph (why you’re writing) → Main paragraphs (your arguments, one idea each) → Closing paragraph (what you want to happen) → Yours faithfully (if Dear Sir/Madam) or Yours sincerely (if you used a name) → Your name. Use formal language: full words (cannot, not can’t), no slang, polite tone, one idea per paragraph.

Ratio compares two quantities. The ratio 3:1 means for every 3 of one thing, there is 1 of another. To simplify a ratio, divide both numbers by the same amount (the HCF). To share in a ratio: add the parts (3+1=4), find what 1 part = (total ÷ 4), then multiply. Example: share £20 in ratio 3:1. Total parts = 4. One part = £5. So it’s £15 and £5. For proportion problems: if 3 items cost £12, one costs £4, five cost £20.

The three averages: Mean = add all values ÷ how many there are. Median = the middle value when sorted in order. Mode = the most common value. Range = largest minus smallest (not an average, measures spread). For percentage change: (new − old) ÷ old × 100. If the answer is positive, it’s an increase. If negative, it’s a decrease. Always show your working — even partial working can earn marks.

Algebra uses letters to represent unknown numbers. To solve an equation, do the same thing to both sides to keep it balanced. Order of operations: Brackets, Indices, Division, Multiplication, Addition, Subtraction (BIDMAS). To expand brackets: multiply everything inside by what’s outside. Example: 3(x + 4) = 3x + 12. To form an equation from a word problem: identify what’s unknown, call it x, translate the words into maths symbols.

Perimeter = the total distance around the outside of a shape (add all sides). Area = the space inside a shape. Key formulae: Rectangle: Area = length × width, Perimeter = 2(l + w). Triangle: Area = ½ × base × height. Parallelogram: Area = base × height. Trapezium: Area = ½(a + b) × h where a and b are the parallel sides. Always include units — area is in cm² or m², perimeter is in cm or m.

Probability measures how likely an event is, on a scale from 0 (impossible) to 1 (certain). To calculate probability: P(event) = number of favourable outcomes ÷ total number of outcomes. Express as a fraction, decimal or percentage. The probability of something NOT happening = 1 − P(it happening). For combined events, if they’re independent (one doesn’t affect the other), multiply the probabilities.