Chapter 3- Biomolecules Flashcards
Why do humans need water?
- It is a solvent for chemical reactions.
- It is an element of transport. (Transport dissolved substances | blood | sweat | urine and excretion)
- It helps to control our body temperature.
- It is the key component of tissues.
Why do plants need water?
- It is essential for photosynthesis.
- It helps keep the plant turgid and firm.
- It transports mineral salts and water up the xylem.
- It transports food down the phloem.
List three types of monosaccharides, disaccharides and polysaccharides. Name as well five types of reducing sugars.
- Glucose | fructose | galactose
- Sucrose | lactose | maltose
- Starch | cellulose | glycogen
- Glucose | fructose | galactose | lactose | maltose
What is a condensation reaction?
A condensation reaction is the process whereby two simple molecules are joined together to form a larger molecule with the removal of water.
What is hydrolysis?
Hydrolysis is the process where a molecule of water is used to break up a large molecule into smaller molecules.
State how the Benedict’s test is carried out.
- Prepare 2cm3 of food sample.
- Add 2cm3 of Benedict’s solution to the sample.
- Shake the mixture thoroughly and submerge in a boiling water bath.
- Blue (none), green (traces), orange (moderate), brick-red (large amounts present).
State the function of starch.
Starch is the storage form of carbohydrates in plants. It is commonly found in storage organs such as potatoes and tapioca.
State the function of cellulose.
Cellulose is used for support structures in plants. It makes up the cell wall. It can also be used as a dietary fibre in humans to prevent constipation.
State the function of glycogen.
Glycogen is the storage form of carbohydrates on humans. It is usually stored in the liver muscles of mammals.
Why are starch and glycogen suitable as storage forms?
- QThey have compact shapes (easily stored in cells).
- They are insoluble (does not affect water potential in cells).
- They are large molecules (cannot diffuse out easily).
- They are easily broken down to glucose and hydrolysed.
State how the starch test is carried out.
- Take 2cm3 of food sample.
- Add a few drops of iodine solution to it.
- If the iodine turns blue-black, starch is present. If it remains brown, starch is absent in the sample.
What is the function of carbohydrates?
- It is can be converted to fats and amino acids.
- It forms nucleic acids such as DNAs.
- Synthesis of lubricants such as mucus.
- Synthesis of nectar in flowers.
- Substrate for respiration. (Glucose + water)
- It is a support structure. (Cellulose)
What are fat molecules made up of?
- Glycerol
- Fatty acid chains
- Ester bond
What is the difference between a saturated fat molecule and an unsaturated fat molecule?
- Saturated fat molecules have only one bond. Unsaturated fat molecules have more than two bonds and have kinky fatty acid chains.
- Saturated fat is unhealthy, while unsaturated is less fatty.
- Saturated fat is in solid state at r.t.p while unsaturated fats are in liquid states at r.t.p.
- Unsaturated fats can also be converted to trans fats in high heat.
State how the Ethanol emulsion test is carried out.
- Add 2cm3 of food sample to 2cm3 of ethanol.
- Shake well and add 2cm3 of water to the mixture.
- The formation of white emulsion means that fats are present.
