BIOLOGY · Stage 8 · Chapter 6: Nutrition, Health and Movement

Biology 6.5 Diet, growth and development

5 min read 5 parts Lesson 5 of 12

0%read

Lesson summary

Biology 6.5 Diet, growth and development — Alhussan International Academy — Biology (Stages 7–9) notes: Explain how a lack of vitamins and minerals causes deficiency diseases and name the functions, sources and symptoms.Lifestyle — each person has an individual lifestyle, and fac…

Balanced diet
Small amounts
Vitamin D and calcium
Respiration
Non-infectious
Night-blindness

Section 1 of 5Diet, lifestyle and deficiency

Lifestyle
- each person has an individual lifestyle, and factors including diet affect every stage of life.
Balanced diet
- everyone needs one for the body to function properly.
Deficiency disease = an illness caused by lacking one component of a balanced diet.
- It affects growth, development and health in children and overall health in adults.
Pregnancy
- if a pregnant woman is malnourished, the development of her baby may be affected before it is born.
Small amounts
- only tiny amounts of vitamins and minerals are needed, but if any is missing a deficiency disease results.

Section 2 of 5Vitamin deficiencies

1Vitamin A3 points

needed for healthy eyes, especially seeing in dim light.
Sources: egg yolks, fish liver oils, dairy products, green vegetables, apricots and carrots.
Deficiency: night-blindness, where the eyes are damaged and cannot see in dim light.

2Vitamin C3 points

helps cells stick together in the skin and takes part in the reactions of aerobic respiration.
Sources: citrus fruits such as oranges, lemons and limes, and tomatoes.
Deficiency: scurvy, with bleeding gums, peeling skin, swollen legs and stopped aerobic respiration, which is eventually fatal.

3Vitamin D4 points

helps bones absorb the calcium they need to be hard and strong.
Sources: fish liver oils, egg yolks and cream, and the skin makes it in sunlight.
Deficiency: rickets, where the bones of growing children cannot absorb calcium, so they are soft and bendy and curve outwards.
In children and adults the bone structure is weakened and teeth crumble away.

Section 3 of 5Mineral deficiencies

1Calcium3 points

needed for strong, healthy bones and teeth.
Sources: dairy products such as milk, yoghurt and cheese.
Deficiency: weak, crumbly bones and teeth, and rickets.

2Iron3 points

needed for the haemoglobin in red blood cells, which picks up oxygen in the lungs and carries it to cells for aerobic respiration.
Sources: red meat, egg yolks, liver, apricots and green leafy vegetables.
Deficiency: anaemia, where red blood cells lack haemoglobin and fewer are made, so the person looks pale and feels tired and weak.

Nutrient	Function	Source	Deficiency disease
Vitamin A	Healthy eyes, sight in dim light	Carrots, liver, green vegetables	Night-blindness
Vitamin C	Holds cells together, helps respiration	Citrus fruits, tomatoes	Scurvy
Vitamin D	Helps bones absorb calcium	Fish liver oil, egg yolks, sunlight	Rickets
Calcium	Strong bones and teeth	Milk, yoghurt, cheese	Rickets, weak bones
Iron	Makes haemoglobin	Red meat, liver, green leafy vegetables	Anaemia

Section 4 of 5Links between deficiencies

Vitamin D and calcium
- both lack of vitamin D and lack of calcium cause rickets, because bones need vitamin D to absorb calcium even if enough is eaten.
Respiration
- scurvy and anaemia both affect aerobic respiration in cells.
- In scurvy cells stop sticking together and respiration stops, so tissues break down.
- In anaemia less oxygen reaches the cells, so aerobic respiration slows, causing tiredness.

Section 5 of 5Cures and prevention

Cure
- eat foods containing the missing nutrient or take supplements.
Sunlight
- people who stay indoors in places with little sun may need vitamin D in their diet.
History
- sailors on long voyages without fresh fruit suffered scurvy until citrus juice was added to rations,
  - and rickets was common in smoky cities with little sunlight.
Today
- fortified foods, such as flour with added iron, help prevent deficiencies.
Non-infectious
- deficiency diseases are not infectious and are preventable with a varied diet.

Last updated: 13 October 2026