WJEC Level 3 Certificate in Food Science and Nutrition

Section 7: Assessment 326 Correct alternative answers could include: (a) Oily fish or butter or egg yolk or liver or whole milk (b) Red peppers or apricots or sweet potato or kale or mangoes Example of an insufficiently detailed answer: (c) Vitamin A is important in the diet of a pregnant woman to help her eyesight. It is important that she does not exceed recommended amounts as this could increase the risk of her baby being born with birth defects. Examiner commentary: Reference just to eyesight is not a detailed enough response to obtain the full 2 marks. The function of retinol in the formation of the pigment rhodopsin (visual purple) in the retina to enhance the mother’s vision in dim light, would need to have been included in the answer. Alternative answers for (c) could include the role of retinol in: Cell growth Embryonic development The production and correct function of mucous membranes Example of an incorrect answer: (a) Egg Examiner commentary: The correct answer is egg yolk, as it is the yolk which is the source of retinol. Section B: Graduated lead in questions Example answers Q1 : Describe the functions of lipids in the diet [2] Lipids are important in the diet for providing the body with fat-soluble vitamins A, D, E and K. Lipids are also a concentrated source of energy, providing more than twice as much energy per gram (9 kcal) as either carbohydrate (3.75 kcal) or protein (4 kcal) Q2 : Explain the difference between saturated and polyunsaturated fatty acids [4] Fatty acids are usually classified as saturated, monounsaturated or polyunsaturated depending on their chemical structure. The carbon atoms of saturated fatty acids have all the hydrogen atoms they can hold, and are therefore saturated with hydrogen. The linear shape of saturated fatty acids causes them to pack closer together, which gives them a rigid stable structure; meaning they are unlikely to react with other chemicals. Generally, fats that contain a high percentage of saturated fatty acids are solid at room temperature and have a high melting point. They tend to be of animal origin, for example butter, as they contain more saturated fatty acids than polyunsaturated fatty acids. Saturated fatty acid Polyunsaturated fatty acid CH H H OH CH C H H C H H C H H H OH CH OH H 2 O CH H H OH CH OH CH OH OH O R C C H H C H H C H H H OH O C C H H C H H C H H H OH O C C H H C H H C H H H OH O C glycerol glycerol fatty acids condensation reaction + 3 molecules H 2 O carboxyl group H 2 O H 2 O CH H H O CH O CH O C H H C H H C H H H O O O C C H H C H H C H H H C C H H C H H C H H H C H H C H H H C H H C H H C H H C H C H H C H H C H H C H C H H H C C H HH H H H H H C H H C H C triglyceride fatty acid 1 ⎫ ⎪ ⎬ ⎪ ⎭ fatty acid 2 ⎫ ⎪ ⎬ ⎪ ⎭ fatty acid 3 ⎫ ⎪ ⎬ ⎪ ⎭ CH H H OH CH C H H C H H C H H OH CH OH H 2 O CH H OH C OH C OH OH O R C C H H C H H C H H H OH O C C H H C H H C H H H OH O C C H H C H H C H H H OH O C glycerol glycerol fatty acids condensation reaction double bond carboxyl group H 2 O H 2 O CH H H O CH O CH O O O O C C C H H C H H H C H H C H H C H H C H C H H H C H H C H C triglyceride In these example questions: Q1 is testing your understanding of the term lipids and subsequently your ability to describe the function of fats in the diet. Q2 requires you to apply your knowledge and understanding of the chemical structure of fats in your explanation. With this type of question, it is considered good practice to include diagrams to support your explanation. Chapter 20: Unit 1 External assessment