Module 1
Health & lifestyle
Quick-reference revision notes for parents.
1.0 Working scientifically
The skills used across every science topic.
- Prediction: a sensible guess at the outcome, based on prior knowledge.
- Variables:
- Independent — the one you change.
- Dependent — the one you measure.
- Control — kept the same to make it a fair test.
- Anomaly: a result that doesn't fit the pattern. Identify and explain — don't just delete.
- Conclusion: states what the data shows; refers back to the prediction.
1.1 Nutrients
A balanced diet contains seven nutrients in the right proportions:
| Nutrient | Function | Example sources |
|---|---|---|
| Carbohydrates | Energy | Bread, pasta, rice |
| Fats & oils | Energy store, insulation | Butter, oils, cheese |
| Protein | Growth and repair | Meat, fish, eggs, beans |
| Fibre | Helps digestion | Vegetables, wholegrains |
| Water | Used in every chemical reaction in the body | Drinks, food |
| Minerals (Ca, Fe) | Calcium for bones; iron for red blood cells | Dairy, red meat |
| Vitamins (A, C, D) | A: vision; C: skin and immune; D: bones | Fruit, veg, sun (D) |
1.2 Food tests
| Nutrient | Reagent | Positive result |
|---|---|---|
| Starch | Iodine solution | Orange-brown → blue-black |
| Sugar (reducing) | Benedict's solution + heat | Blue → brick-red precipitate |
| Protein | Biuret reagent | Blue → purple/lilac |
| Fat (lipid) | Ethanol then water | Cloudy white emulsion |
Memory hook
"Iodine for starch, Benedict's for sugar, Biuret for protein." The vowels match the test.
1.3 Unhealthy diet
- Too much energy in (carbs/fats) → stored as fat → obesity → linked to heart disease, type 2 diabetes.
- Too little food → starvation, low energy, weakened immune system.
- Deficiency diseases:
- Iron → anaemia
- Vitamin C → scurvy
- Vitamin D / calcium → rickets
1.4 Digestive system
Order food travels through:
mouth → oesophagus → stomach → small intestine → large intestine → rectum → anus
| Organ | Job |
|---|---|
| Mouth | Chewing breaks food up; saliva starts digesting starch. |
| Oesophagus | Tube to the stomach (peristalsis squeezes food down). |
| Stomach | Acid kills microbes; enzymes digest protein. |
| Small intestine | Most digestion + absorption of nutrients into the blood. |
| Large intestine | Absorbs water; forms faeces. |
| Liver | Makes bile (emulsifies fats). |
| Pancreas | Releases digestive enzymes into the small intestine. |
Adaptation worth knowing
The small intestine is long and lined with villi (tiny finger-like folds). This gives a huge surface area for absorbing nutrients into the blood.
1.5 Bacteria and enzymes in digestion
- Enzymes are biological catalysts — they speed up the breakdown of large food molecules into small ones the body can absorb.
- Three main types: amylase (starch → sugar), protease (protein → amino acids), lipase (fat → fatty acids + glycerol).
- Gut bacteria in the large intestine help digest fibre and produce some vitamins.
1.6 Drugs
A drug is a substance that affects the way the body works.
- Medicinal — prescribed to treat illness (e.g. paracetamol, antibiotics).
- Recreational — taken for the effect they cause; many are addictive.
- Stimulants speed up the nervous system (e.g. caffeine).
- Depressants slow it down (e.g. alcohol).
1.7 Alcohol
- Alcohol is a depressant — slows reactions, impairs judgement.
- Long-term: damages the liver (cirrhosis), brain and heart.
- Pregnant women are advised not to drink — alcohol crosses the placenta and harms the developing baby.
1.8 Smoking
Three main harmful substances in tobacco smoke:
| Substance | Effect |
|---|---|
| Nicotine | Highly addictive; raises heart rate and blood pressure. |
| Tar | Coats the airways; causes cancer (lung, mouth, throat). |
| Carbon monoxide | Binds to red blood cells, reducing oxygen carried. |
Smoking damages tiny hairs (cilia) in the airways that normally sweep mucus + dirt up and out — this is why smokers cough.
Quick reference
- 7 nutrients: carbs, fats, protein, fibre, water, minerals, vitamins
- Food tests: iodine (starch), Benedict's (sugar), Biuret (protein), ethanol (fat)
- Digestion order: mouth → oesophagus → stomach → small → large intestine
- Enzymes: amylase, protease, lipase
- Smoking damages: nicotine (addiction), tar (cancer), CO (less oxygen)