B3

Question 1

Explain how sodium hydroxide unblocks the drain.

Answer 1

It hydrolysis the bonds
Glycerol and soap salts of fatty acids
Prodcuts are water soluble and drain away

Question 2

3 types of fats and their function

Answer 2

triglicerides ( long-term energy storage, thermal insulation)
phospholipids ( cell membrane, electrical insulation in neurons(no delocalized electrons))
steroids - hormones

Question 3

use and abuse of steroids

Answer 3

• oral contraceptive pills and hormonal therapy
• recuperation from illness and rebuilding of lost musscles
• anabolic steroids to increase muscle mass unfair advantage in sports

Question 4

cholesterol

Answer 4

steroid transported in lipoproteins
- LDL transports cholesterol to arteries, atherosclerosis. source of LDL cholesterol are saturated fatty acids
- HDL transport cholesterol from the arteries to the liver

Question 5

why fats are good energy storage?

Answer 5

• less oxidised
• burning is more exothermic

Question 6

oxidative and hydrolytic rancidity

Answer 6

oxidative
site of reactivity is C=C
temperature, oxygen availability increases the rate
reduced by refrigerating

hydrolytic
site of reactivity ester linkages between glycerol and fatty acids
fatty acids released cause unpleasant smell
moisture, temperature, light increases the rate
catalysed by enzymes, light

Question 7

carbohydrates vs fats as energy storage

Answer 7

fats are more reduced
carbohydrates are soluble in water (hydrogen bonds) lipids are insoluble in water as they are hydrophobic