DietCambridge IGCSE Biology: Flashcards

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Define what is meant by a balanced diet.

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Define what is meant by a balanced diet.: A balanced diet is one that contains all the nutrients needed in the correct proportions to maintain good health, support growth, and provide energy. It includes carbohydrates, fats, proteins, vitamins, mineral ions, fibre and water in appropriate amounts.
Name three principal dietary sources of carbohydrates.: Bread, rice, pasta, potatoes, and cereals are principal dietary sources of carbohydrates. (Any three of these acceptable.)
What is the importance of carbohydrates in the diet?: Carbohydrates provide energy for metabolism and physical activity. They are broken down to glucose, which cells use for respiration to release energy.
Name two principal dietary sources of fats and oils.: Butter, oils, nuts, seeds, fatty fish, meat, and dairy products such as milk and cheese are principal sources of fats and oils. (Any two acceptable.)
Explain the importance of fats and oils in the diet.: Fats and oils provide energy (more than twice as much energy per gram as carbohydrates), insulation, and protection of organs. They are also important for the absorption of fat-soluble vitamins.
Name three principal dietary sources of proteins.: Meat, fish, eggs, beans, lentils, nuts, and dairy products such as milk and cheese are principal sources of protein. (Any three acceptable.)
What is the importance of proteins in the diet?: Proteins are needed for growth and repair of tissues, making enzymes and hormones, and producing antibodies for the immune system. They can also be used for energy if carbohydrates and fats are insufficient.
Name two principal dietary sources of vitamin C.: Citrus fruits (oranges, lemons), berries, kiwi fruit, tomatoes, peppers, and leafy green vegetables are principal sources of vitamin C. (Any two acceptable.)
What is the importance of vitamin C and what disease does deficiency cause?: Vitamin C is needed for the formation and maintenance of collagen in connective tissues, promoting wound healing and immune function. Deficiency causes scurvy, which involves poor wound healing, bleeding gums, and weakened connective tissue.
Name two principal dietary sources of vitamin D.: Oily fish (salmon, mackerel), egg yolks, fortified milk, and sunlight exposure (skin synthesis) are principal sources of vitamin D. (Any two acceptable.)
What is the importance of vitamin D and what disease does deficiency cause?: Vitamin D is needed for the absorption of calcium and phosphate, which are essential for strong bones and teeth. Deficiency causes rickets, characterised by weak and deformed bones, particularly in children.
Name two principal dietary sources of calcium ions.: Milk, cheese, yoghurt, leafy green vegetables, and fortified foods are principal sources of calcium. (Any two acceptable.)
What is the importance of calcium ions in the diet?: Calcium ions are essential for the formation and maintenance of strong bones and teeth, and for muscle contraction and nerve transmission.
Name two principal dietary sources of iron ions.: Red meat, liver, beans, lentils, fortified cereals, and leafy green vegetables are principal sources of iron. (Any two acceptable.)
What is the importance of iron ions in the diet?: Iron ions are needed to make haemoglobin in red blood cells, which transports oxygen around the body. Deficiency causes anaemia, resulting in tiredness and breathlessness.
Define fibre (roughage) and name two principal dietary sources.: Fibre or roughage is indigestible plant material, including cellulose. Principal sources are vegetables, fruits, wholegrain cereals, beans, and lentils. It aids digestion by promoting peristalsis and prevents constipation.
What is the importance of water in the diet?: Water is essential for all metabolic reactions, transporting nutrients and waste products, maintaining body temperature through sweating, and keeping joints lubricated. It is a major component of cells and blood.