Carbohydrates and Lipids Flashcards
What is a monomer? (1)
A monomer is a small, identical molecule from which larger molecules called polymers are made via condensation reactions
What is a polymer? (1)
Polymers are large molecules made from joining 3 or more similar monomers together
What is a condensation reaction? (1)
removal of one water molecule which forms a bond
What is a hydrolysis reaction? (1)
addition of one water molecule to break a bond
Give 2 examples of monomers (2)
Alpha/Beta glucose
Nucleotides
Amino acids
Give 2 examples of polymers (2)
Nucleic Acids
Cellulose
Starch
Protein
Name the bond formed between two monosaccharides (1)
Glycosidic bond
Draw the structure of alpha glucose (1)
https://www.google.com/search?q=structure+of+alpha+glucose&rlz=1C1VDKB_en-GBGB967GB967&sxsrf=ALiCzsa9otHIICek5tboH32WQ6Ai9k1dTA:1651412793402&source=lnms&tbm=isch&sa=X&ved=2ahUKEwiUmLaHuL73AhWSX8AKHRSzAr0Q_AUoAXoECAEQAw&biw=1280&bih=601&dpr=1.5#imgrc=Od39dZJh972gdM
Which monosaccharides form maltose and which enzyme is used to hydrolyse maltose? (2)
Alpha Glucose and Alpha Glucose
Enzyme - Maltase
Which monosaccharides form lactose and which enzyme is used to hydrolyse lactose? (2)
Alpha Glucose and Galactose
Enzyme - Lactase
Which monosaccharides form sucrose and which enzyme is used to hydrolyse sucrose? (2)
Alpha Glucose and Fructose
Enzyme - Sucrase
Give three features of starch and explain how these enable it to act as a storage substance. (3)
Helical so compact
Insoluble so doesn’t affect water potential
Large molecule so does not leave cell
Branched chains (1:4 and 1:6 glycosidic bonds) so rapid hydrolysis to remove glucose for respiration
The structure of cellulose is related to it’s role in plant cell walls. Explain how. (3)
Long straight unbranched chains of beta glucose monomers
Joined by MANY WEAK hydrogen bonds
Form microfibrils
Provide increased strength
Hydrogen bonds are important in cellulose molecules. Explain why. (2)
Holds cellulose chains together
Provides strength
Many weak hydrogen bonds provide strength in large numbers
Describe how lactose is formed and where in the cell it would be attached to a polypeptide to form a glycoprotein (3)
Glucose and Galactose
Joined by condensation reactions
Forms glycosidic bond
Added to [polypeptide in Golgi Body
Describe how the student would show that reducing sugars were present in a solution. (3)
Add equal volume of Benedict’s Solution
Heat to 95*C
Red/orange/green PRECIPITATE formed shows reducing sugar is present
Describe how a student would show that a non-reducing sugar is present in the solution
(5)
Complete Benedict’s test and observe negative result
Add HCl to sugar solution AND heat to 95C
Neutralise with alkali
Add equal volume of Benedict’s solution
Heat again to 95C
Red/Orange/Green PRECIPITATE formed
Describe how you would test a sample of food for the presence of starch. (2)
Add Potassium Iodide (KI) solution
Blue/Black indicates starch is present
What is a triglyceride made from and what bond is formed between them? (1)
3 fatty acids bonded via an ester bond to one glycerol molecule
What is a saturated fatty acid? (1)
Do not have double bonds between carbon atoms within the hydrocarbon chain
What is an unsaturated fatty acid? (1)
Double bonds between carbon atoms within the hydrocarbon chain
Some seeds contain lipids. Describe how you could use the emulsion test to show that a seed contains lipids. (3)
Crush the seed
MIX with ethanol and SHAKE
Add water AND shake
Forms cloudy white emulsion
What is a structural difference between a phospholipid and a triglyceride? (1)
Fatty acid is removed and replaced with a phosphate group
Compare and contrast the structure and properties of triglycerides and phospholipids. (5)
Both contain ester bonds
Both contain glycerol
Fatty acids on both may be saturated or unsaturated
Both are insoluble in water
Triglyceride has three fatty acids and phospholipids have two fatty acids plus phosphate group
Triglycerides are hydrophobic and phospholipids have hydrophilic and hydrophobic region
Phospholipids form bilayer but triglycerides don’t
A student carried out the Benedict’s test. Suggest a method, other than using a colorimeter, that this student could use to measure the quantity of reducing sugar in a solution. (2)
Filter and dry the precipitate
Find the mass
Explain how the digestion of starch in the small intestine leads to an increase in the concentration of glucose in the blood. Details of co-transport are not required. (3)
Starch is hydrolysed by amylase
Produces glucose
Small enough to cross the gut wall into the blood
Describe the structure of glycogen (2)
- Polymer of alpha glucose
- Joined by glycosidic bonds
Suggest how glycogen acts as a store of energy (2)
- Hydrolysed
- Glucose used in respiration
