Chapter 2 - Human Nutrition Flashcards
Edexcel iGCSE Biology
Name the three main chemical elements that are found in carbohydrates.
Carbon, Oxygen and Hydrogen
What types of biological molecules are made up of Fatty Acids and Glycerol?
Lipids
What types of biological molecules are made up of Amino Acids?
Protein
Describe how you would use Benedict’s solution to test for glucose.
- prepare a food sample, transfer 5cm3 to a test tube.
- prepare a water bath, 75 degrees C
- Add ~10 drops of Benedict’s solution to test tube
- place test tube in water bath for 5 minutes
- Note colour change
what colour will Benedict’s solution turn if a high glucose is present?
Brick-Red
what colour will Benedict’s solution turn if a low Glucose concentration is present?
Green or Yellow
What solution could you use to see if there’s starch in a sample?
Iodine solution
Describe how you would test for starch with iodine solution
- Prepare a food sample, transfer 5cm3to a test tube
- add a few drops of iodine solution and gently shake the tube.
- Note the colour change
What colour does iodine solution turn in the presence of starch?
Brown-Orange to Blue-Black
what nutrients does the body get energy from?
Carbohydrates, Lipids and Protein
Why does the body need proteins?
Growth and Repair
What foods contain proteins?
meat and fish
Eric has just been to see his doctor. He has been told that he needs to increase the amount of Vitamin D in his diet. Why might Eric need Vitamin D?
To help the body absorb calcium for strong teeth and bones.
explain fully what is meant by the term ‘a balanced diet’
A balanced diet supplies all your essential nutrients in the right proportions.
Explain the difference in energy requirement between children and older people.
Children require more energy as they are generally more active.
explain the difference in energy requirements between a pregnant woman and a non-pregnant woman
The pregnant woman needs more energy so her baby can develop
Describe a simple experiment to measure the amount of energy in a food
- weigh a small amount of the food, pick it up with a mounted needle
- add a set volume of water to a boiling tube.
- measure the temperature of water and light the food sample.
- immediately, hold the food under the boiling tube until it goes out.
- Measure the temperature change.
energy in food = Mass of water x Temperature change of water x 4.2
give one way you could make the experiment to measure the amount of energy in a food more accurate
Insulate the boiling tube, E.G. with foil. this would minimise heat loss and keep more energy in water.
What is the main role of digestive enzymes?
break down big molecules into smaller ones
Name the enzyme that converts starch into glucose
amylase converts starch into maltose… maltase converts maltose into glucose
what does protease do?
Protease converts proteins into amino acids
when lipids are digested, what molecules are they broken down into?
glycerol and fatty acids
Where in the body is bile stored?
bile is stored in the gall bladder
Where in the body is bile produced?
Bile is produced in the liver
