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
What is a Monomer?
These are the smaller molecules
What elements are found in Carbohydrate?
C,H,O
What elements are found in Protein?
C,H,O,N
What elements are found in Lipids?
C,H,O
What are the properties of Carbohydrate?
.Large insoluble storage Molecule
What are the properties of Protein?
.Have specific shape for their function
What are the properties of Lipids?
.Can either be liquids (oil) or solids (fats) at room temp.
What are the smaller basic unit and larger molecule of Carbohydrate?
Glucose
Starch (plants)
Glycerol (Animal)
What are the smaller basic unit and larger molecule of Protein?
Amino Acids
Polypeptide chains eg: protein hormones
What is the smaller basic unit and larger molecule of Lipids?
Glycerol backbone and three fatty acids
What is a deficiency?
Too little of something
Consequences of Vitamin C deficiency?
Scurvy- Bleeding in the gums and wounds which do not heal.
Consequences of Vitamin D deficiency?
Rickets (softening of the bones)
Consequences of Vitamin A deficiency?
Night Blindness
Consequences of Iron deficiency?
Anaemia- due to the reduction in the number of red blood cells so the person may feel tired.
Consequences of Calcium deficiency?
Rickets (softening of the bones)
Consequences of Protein deficiency?
Kwashiorkor-symptoms include swelling of the abdomen, wasting muscles, thinning hair and loss of teeth
What is the test for Protein (Biuret Test)?
Add an equal volume of sodium hydroxide to the solution of the food being tested and mix. Then add a few drops of copper sulfate.
Positive: Blue -> Purple
Test for Fat (Emulsion Test)?
Dissolve the food being tested into ethanol. Pour this solution into a clean test tube of water.
Positive: White Elmusion
What does Amylase break down and where does it break it down?
Amylase breaks down Starch to maltose in salivary glands (Mouth)
Amylase Breaks down Starch to Maltose in Pancreas in Small Intestine
What does Maltase break down and where?
Maltase breaks down Maltose into glucose in the wall of small intestine
What does Pepsin break break down and where?
Proteins –> Peptides
in Stomach Wall
What does Trypsin break down and where?
Proteins to Peptides in Pancreas (small intestine)
What does Peptidases break down and where?
Peptides to amino acids in the wall of the small intestine
What does Lipase break down and where?
Lipids to Glycerol and three fatty acids in the pancreas
Describe the process of Digestion
.Begins in mouth
.Saliva helps moisten food and contains the enzyme amylase breakdowns starch
.Chewed lump of food mixed with saliva passes along the oesophagus to stomach
.Initial Digestion of Protein takes place
. Stomach wall secretes Hcl so stomach contents are strongly acidic
. Semi digested food is held back in stomach by a ring at the outlet of the stomach (Sphincter Muscle)
. When it relaxes it releases food into the first part of duodenum
. Several digestive enzymes are added to the food in the duodenum (Made by Pancreas)
. Liver makes Bile which turns any large lipid globules into an emulsion of tiny droplets
. This increases SA of lipid –> easily broken down by Enzyme
. Bile is alkaline so neutralises semi digested food coming from stomach
. More Enzymes are added, until parts of food that are digested can be fully broken down into soluble end products.
. Ileum absorbs food
. Most digested food is already absorbed.
. Semi solid waste is remaining (faeces which is stored in the rectum and expelled out the body through anus)
What pH is pepsin and why?
2 because the stomach is acidic after the stomach wall secretes Hydrochloric acid and it is its optimum temperature
Adaptions to absorption of the Ileum?
Lining of Ileum has very large SA, which means it can quickly and efficently absorb through the soluble products of digestion into the blood. (This is helped by the length of the Intestine)
It’s very long, time to break down and absorb all the food before it reaches the end
Contains Microvilli which increases surface area for absorption even more
Villi has a single permeable layer of surface cells and a very good blood supply to assist quick absorption
