Biological Molecules Y9 Flashcards
What is a Balanced Diet?
A balanced diet consists of having 7 key nutrients of food but all in their correct proportion.
What are the 7 groups of food in a balanced diet?
Carbohydrates Protein Dairy Vitamins Fats Minerals Fibre Water
What is the purpose of a Carbohydrate?
This breaks down food into glucose which can then be used for respiration.
Eg: Fruit, Pasta and Bread
What is the purpose of Fat?
This is used as a Long term energy store . Provides Thick insulation . Helps protect internal Organs . Component of the Cell Membrane Eg; Butter, Oil
What is the purpose of Vitamin A?
.Forms a pigment needed for vision
. Protects the surface of the eye
Eg; Liver, Fish Oil, Eggs
What is the purpose of Vitamin C?
Needed for healthy, skins, gum and healing
What is the purpose of Vitamin D?
Needed for the absorption of calcium which keeps strong and healthy bones and teeth
Eg: Sunlight
What is the Purpose of Protein?
Needed for Growth and repair
What is the purpose of Minerals? Calcium and Iron?
Calcium- Needed for strong, healthy teeth and bones
Iron- Needed to make haemoglobin which binds with O2 to carry O2 around the body
What is the purpose of Fibre?
Needed to provide roughage and keep food moving through the gut by peristalsis.
. Prevents constipation
Eg; Dates, Prunes
What is the purpose of Water?
To hydrate
Why would someone gain weight?
When their energy intake is greater than their energy output meaning that they will have spare energy which will convert into fat
Essential Practical:
How much energy is in food?
- A food sample is weighed and the mass is noted
- A boiling tube is filled with a known volume of water which is recorded. The temp should also be recorded
- The food sample is then put into a burning spoon and ignite
- The food sample is quickly placed underneath the boiling tube. As soon as the food is completley burnt we will stop
- Energy Released from Food per gram (J) =
mass of water (g) x temp rise x 4.2/
mass of food sample (g)
What is wrong with this practcial?
. Innacurate and understimates the the enrgy in food
. Not all the food energy is transferred into the water
. Energy is lost in the air and glass
How to modify the method to improve accuaracy?
. Burn the food closer to the tube -> less heat lost to the air
. Stir the water -> Heat energy evenly spread
. Using a bomb Calorimeter -> O2 rich enviroment ensures complete combustion of food
. Using a temp probe to give more precise readings of temp, as there are smaller intervals between each measurements
Food test for Glucose
Reagent Used : Benedict Reagent
Positive Result: Brick Red
Negative Result: Blue
Food test for Starch
Reagent used: A few drops of iodine
Positive Result: Blue/Black
Negative Result: Orange/Brown
What are Polymers?
Polymers are very large molecules when smaller molecules join together end-to-end