Nutrients and food testsIB MYP Biology: Flashcards
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What is the main function of carbohydrates?
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- What is the main function of carbohydrates?
- To provide energy.
- What are proteins needed for?
- Growth and repair.
- What are two functions of lipids?
- An energy store and insulation.
- What is iron needed for?
- To make haemoglobin in red blood cells.
- What is calcium needed for?
- Strong bones and teeth.
- What does vitamin D do?
- Helps the body absorb calcium, so bones are hard.
- Which test shows starch, and what is the positive result?
- Iodine solution: orange-brown to blue-black.
- Which test shows reducing sugar, and what is the positive result?
- Benedict's solution, heated: blue to brick-red.
- Which test shows protein, and what is the positive result?
- Biuret solution: blue to purple.
- Which test shows lipid, and what is the positive result?
- Ethanol emulsion test: a cloudy white emulsion in water.
- How is the energy content of a food measured?
- By burning it under water and measuring the temperature rise.
- Why is the energy found by burning a food too low?
- Some heat is lost to the surroundings and the food may not burn completely.
- Which deficiency diseases are caused by lack of vitamin C, vitamin D, iron and protein?
- Scurvy, rickets, anaemia and kwashiorkor.
- What is obesity, and what two diseases is it linked to?
- Being very overweight from taking in more energy than is used; type 2 diabetes and heart disease.
- Why does energy need vary between people?
- It depends on age, size and activity level.
Exam questions on Nutrients and food tests
- A 15-year-old girl in Doha eats very little red meat or green vegetables. She feels tired all the time, and her doctor finds that she has anaemia.Explain why a lack of iron makes the girl feel tired.2 marks
- Sailors on long sea voyages in the 1700s, who ate no fresh fruit, often developed bleeding gums and wounds that would not heal. Today, some children whose diets contain too little vitamin D develop soft, bent leg bones.Explain why a diet low in vitamin D leads to soft bones.2 marks
- A student has four unlabelled food samples, W, X, Y and Z, each mixed with water. She tests each one with iodine solution, with Benedict's solution (heated in a water bath), with biuret solution, and with the ethanol emulsion test. Sample W turns blue-black with iodine and gives no other change. Sample X turns brick-red with Benedict's solution and purple with biuret solution, and gives no other change. Sample Y gives a cloudy white layer in the ethanol emulsion test and no other change. Sample Z gives no change in any test.State the nutrient or nutrients present in samples W, X and Y.3 marks
Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).