2.3 Syllabus
U1. Monosaccharide monomers are linked together by condensation reactions to form disaccharides and polysaccharide polymers.
-Carbohydrates are made of C, H and O
-Carbohydrates are composed of recurring monomers called monosaccharides (which typically form ring structures)
These monosaccharides may be linked together via condensation reactions (water is formed as a by-product)
-Carbohydrates are composed of recurring monomers called monosaccharides (which typically form ring structures)
These monosaccharides may be linked together via condensation reactions (water is formed as a by-product)
- Two monosaccharide monomers may be joined via a glycosidic linkage to form a disaccharide
- Many monosaccharide monomers may be joined via glycosidic linkages to form polysaccharides
u2. Fatty acids can be saturated, monounsaturated and polyunsaturated.
-Fatty acids are long hydrocarbon chains that are found in certain types of lipids (triglycerides & phospholipids)
-Fatty acids that possess no double bonds are saturated (have maximum number of H atoms)
-Fatty acids that possess no double bonds are saturated (have maximum number of H atoms)
- Linear in structure, and are typically solid at room temperatures
- Bent in structure, and are typically liquid at room temperatures
U3. Unsaturated fatty acids can be cis or trans isomers.
Cis: The hydrogen atoms attached to the carbon double bond are on the same side. (Always Liquid)
Trans: The hydrogen atoms attached to the carbon double bond are on different sides. Generally linear in structure (despite being unsaturated) and are usually solid at room temperature
Trans fatty acids do not commonly occur in nature and are typically produced by an industrial process called hydrogenation
Trans: The hydrogen atoms attached to the carbon double bond are on different sides. Generally linear in structure (despite being unsaturated) and are usually solid at room temperature
Trans fatty acids do not commonly occur in nature and are typically produced by an industrial process called hydrogenation
u4. Triglycerides are formed by condensation from three fatty acids and one glycerol.
-Triglycerides are the largest class of lipids and function primarily as long-term energy storage molecules
- Animals tend to store triglycerides as fats (solid), while plants tend to store triglycerides as oils (liquid)
A1. Structure and function of cellulose and starch in plants and glycogen in humans.
A2. Scientific evidence for health risks of trans fat and saturated fatty acids.
-Saturated fats and trans fats raise blood cholesterol levels, while (cis) unsaturated fats have lower blood cholesterol levels
-Fats and cholesterol cannot dissolve in blood and are consequently packaged with proteins (to form lipoproteins) for transport
-Fats and cholesterol cannot dissolve in blood and are consequently packaged with proteins (to form lipoproteins) for transport
- Low density lipoproteins (LDL) carry cholesterol from the liver to the rest of the body
- High density lipoproteins (HDL) scavenge excess cholesterol and carry it back to the liver for disposal
A3. Lipids are more suitable for long term energy storage in humans than carbohydrates.
-Carbohydrates
- More easily digested than lipids, good for energy storage that needs to be more rapidly released
- Soluble in water → easier to transport in blood
- Can store more energy per gram than carbohydrates → better for long term energy storage
- Not soluble in water, also harder to break down and transport around the body (build-up of high energy content fats)
A4. Evaluation of evidence and the methods used to obtain the evidence for health claims made about lipids.
There are two main health claims made about lipids in the diet:
- Diets rich in saturated fats and trans fats increase the risk of CHD
- Diets rich in monounsaturated and polyunsaturated (cis) fats decrease the risk of CHD
S1. Determination of body mass index by calculation or use of a nomogram.
The body mass index (BMI) provides a measure of relative mass based on the weight and height of the individual
