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Deficiency diseases are the diseases which occur mainly due to the lack of one or more nutrients in the diet over a long period of time. 
 

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Sources: 1 Mark
Functions: 1 Mark
Depending on its origin, there are two types of proteins - animal proteins and plant proteins. Animal proteins come from food like eggs, fish, meat and milk.  Plant proteins come from pulses, beans, soya bean, etc.
Proteins act as building blocks and are needed by the body for growth and repair.

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Disease: 1 Mark
Symptoms: 1 Mark
Deficiency of vitamin C causes scurvy.
The symptoms of scurvy include weakness, nausea, bleeding gums, joint and muscle pain.

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Vitamin A promotes good vision and maintains healthy eyes and skin.

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1 Mark each
The three main types of foods are energy giving foods, body-building foods, and protective foods.  
1. Energy-giving foods: They are made of carbohydrates and fats. Carbohydrates provide us with instant energy, while fats are stored as energy resources.
2. Body-building foods: Proteins are considered to be body-building foods as they help in body growth and also help in repairing damaged parts of the body.
3. Protective foods: Protective foods are mainly vitamins and minerals since they protect us from many diseases. They give us resistance against disease-causing germs.

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Definition: 1 Mark
Examples: 1 Mark each
PEM stands for Protein Energy Malnutrition. Lack of proteins in the diet results in the development of diseases related to PEM. Kwashiorkor and Marasmus are two types of diseases related with protein energy malnutrition.
1. Kwashiorkor is a disease that predominantly affects children under five years of age, if they do not get enough protein in their regular diet.
2. Marasmus is a disease that affects mostly infants who feed on mother's milk which is poor in protein content.

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Diseases: 1 Mark each
Any three: 
1. Iron deficiency: Lack of iron in the diet leads to a deficiency disease called anaemia.
Symptoms of anaemia include headaches, dark patches under the eyes and general weakness.
2. Iodine deficiency: Lack of iodine in the diet leads to a deficiency disease called goitre. 
 In adults, goitre results in swelling of glands near the throat. In children, iodine deficiency causes stunted mental and physical development.
3. Calcium deficiency: Lack of calcium in the diet makes the bones weak and brittle. It can also cause tooth decay.
Symptoms of calcium deficiency are weak bones and teeth, stunted growth and excessive bleeding from wounds.
4. Phosphorous deficiency: Lack of phosphorous in the diet makes the bones weak and brittle. It also causes improper functioning of the heart and muscles and causes errors in the formation of DNA.
Symptoms include fragile bones and teeth, and disorders in the muscular system.
 

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1 Mark each
The following steps are performed to test the presence of starch in a food item.

1. A small quantity of the food item to be tested is taken.
2. The food sample is then diluted with two drops of water.
3. 2-3 drops of iodine solution are added to it. 
4. Once the iodine solution is added, the colour change in the food sample is observed.
5. Change of colour in the food sample into blue-black indicates the presence of starch in it.

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1 Mark each
1. A small quantity of the food item to be tested is taken. If the food is solid, it should be either made into a paste or powdered.
2. Some of the food material is taken in a clean test tube and 10 drops of water are added to it. These are then mixed properly by shaking the test tube.
3. Using a dropper, two drops of copper sulphate solution is added to the test tube followed by ten drops of caustic soda solution.
4. The contents are mixed well and the test tube is allowed to stand for a few minutes.
5. If the solution turns violet,  it indicates the presence of protein in the food item.

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Disease + symptoms: 1 Mark each

$\begin{array}{ccc}\text{Vitamin/Mineral}& \text{Disease}& \text{Symptom}\\ \text{Vitamin A}& \text{Night blindness}& \text{Loss of vision in darkness}\\ \text{Vitamin C}& \text{Scurvy}& \text{Bleeding gums}\\ \text{Vitamin D}& \text{Rickets}& \text{Soft and bent bones}\\ \text{Iodine}& \text{Goiter}& \text{Swollen neck glands}\\ \text{Iron}& \text{Anaemia}& \text{Extreme weakness}\end{array}$