BIOLOGY · Stage 8 · Chapter 6: Nutrition, Health and Movement
Biology 6.12 Chapter 6 Review: Nutrition, Health and Movement — Alhussan International Academy - Biology (Stages 7-9) Revision Notes & Topical Questions
5 min read 6 parts Lesson 12 of 12
Lesson summary
6.12 Chapter 6 Review: Nutrition, Health and Movement — Alhussan International Academy — Biology (Stages 7–9) notes: Revise the key ideas about diet, smoking, scientific evidence, the skeleton and muscles from Chapter 6.Balanced diet — it contains carbohydrates and fats for energ…
- Fats and oils (lipids)
- Deficiency diseases
- Excess energy food
- Carbon monoxide
- Correlation
- Building confidence in a claim
Section 1 of 6Balanced diet and deficiencies
- Balanced diet
- it contains carbohydrates and fats for energy, protein for growth and repair, vitamins and minerals in small amounts, fibre and water.
- The energy a person needs depends on age, activity and body size.
- Fibre keeps food moving through the gut, so a high-fibre diet gives more faeces and food passes through in about 24 hours.
- With low fibre, less faeces is produced and food may stay in the gut for several days.
- Carbohydrates
- they supply energy, and rich foods include rice, bread and potatoes.
- Fats and oils (lipids)
- they supply energy in a concentrated form, insulate and protect organs, and are found in butter and vegetable oil.
- Deficiency diseases
- each follows from a lack of one nutrient.
- Lack of vitamin C causes scurvy.
- Lack of vitamin D or calcium causes weak bones (rickets), because calcium is not used to harden the bones.
- Lack of iron causes anaemia.
- Rickets has two possible causestoo little vitamin D in the diet, or too little sunlight to make it.
- Excess energy food
- it leads to obesity and a higher risk of type 2 diabetes and heart disease.
- A BMI over 30 signals a risk of heart disease, type 2 diabetes and high blood pressure.
Section 2 of 6Food tests
| Nutrient | Test | Positive result |
|---|---|---|
| Starch | Iodine solution | Blue-black |
| Reducing sugar | Benedict's reagent, heated | Orange-red |
| Protein | Biuret reagent | Purple |
| Fat | Ethanol emulsion test | Cloudy white |
Section 3 of 6Smoking and the body
- Nicotine
- it is addictive and raises the heart rate.
- Tar
- it contains carcinogens and destroys cilia in the airways.
- Carbon monoxide
- it reduces the oxygen carried by haemoglobin.
- Diseases
- smoking causes lung cancer, bronchitis, emphysema and heart disease.
- It also harms passive smokers and unborn babies.
Section 4 of 6Scientific evidence about health
- Correlation
- it shows a link between two variables, not a cause.
- Building confidence in a claim
- scientists use several checks.
- Large representative samples and control groups.
- Repeated results and a known mechanism.
- Peer review of the work.
- Judging a claim
- look at the sample size, the controls and who carried out the work.
- Health between countries
- it differs because of nutrition, water, healthcare, education and income.
Section 5 of 6Skeleton, joints and muscles
- Functions of the skeleton
- it supports, protects, allows movement, makes blood cells and stores minerals.
- Synovial joints
- they contain cartilage, synovial fluid and a membrane, and are held by ligaments.
- The hip and shoulder are ball and socket joints.
- The elbow and knee are hinge joints.
- Muscles
- they contract to pull on bones through tendons and can only pull, never push.
- They work as antagonistic pairs such as biceps and triceps.
- One muscle of the pair contracts while the other relaxes.
Section 6 of 6Linking ideas across the chapter
- Smoking and exercise
- carbon monoxide lowers the oxygen in the blood.
- The muscles then respire anaerobically sooner and lactic acid builds up.
- Evaluating a diet claim
- check the sample size, the controls and whether the correlation has a plausible mechanism.
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