Lipids

Question 1

where do lipids occur ?

Answer 1

occur in mammals as fats and n plants as oils

Question 2

what are the two types of lipids ?

Answer 2

triglycerides and phospholipid

Question 3

what are triglycerides composed of ?

Answer 3

condensations reactions between one glycerol molecule and 3 fatty acids

Question 4

what is the bond formed between glycerol and fatty acid ?

Answer 4

ester bond

Question 5

what are the two types of fatty acid ?

Answer 5

saturated lipids and unsaturated lipids

Question 6

where are saturated lipids found ?

Answer 6

animal fats

Question 7

saturated lipids contain ..

Answer 7

hydrocarbon chain has only single bonds between carbon atoms

Question 8

where are unsaturated found ?

Answer 8

plants

Question 9

unsaturated lipids consists ..

Answer 9

of hydrocarbon chain with at least one double bond between carbons

Question 10

why does unsaturated lipids have a lower melting point ?

Answer 10

intermolecular forces are weaker

Question 11

What state are the two types of lipids at room temperature ?

Answer 11

saturated lipids - solid
unsaturated lipids - liquid

Question 12

Properties of Triglycerides

Answer 12

• large ratios of energy storing carbon hydrogen bonds a lot of energy is stored
• act as a metabolic water source, release water if they are oxidised
• do not affect water potentials and osmosis, large and hydrophobic - insoluble in water
• low mass so stored without increasing the mass and preventing movement

Question 13

What are the roles of lipids in living organisms ?

Answer 13

• energy storage
• waterproofing
• insulation
• electrical insulation

Question 14

Energy storage

Answer 14

• triglycerides are oxidised during respiration so energy is released
• some is lost to the environment as heat to make ATP
• fat store - endure seasons

Question 15

Waterproofing

Answer 15

• repel water - hydrophobic
• sebaceous glands act as a water repellent

Question 16

Insulation

Answer 16

• lipids are poor conductors
• restricted blood supply so little body heat is distributed to the fat under the skin

Question 17

where are triglycerides stored in mammals ?

Answer 17

adipose tissue - subcutaneous tissue

Question 18

Where is myelin found ?

Answer 18

surface membranes if cells that wrap around the long fibres of nerve cells in animals

Question 19

many fibres insulate fibre to ..

Answer 19

prevent the passage of sodium and potassium ions

Question 20

what is phospholipid composed of

Answer 20

two fatty acids and a phosphate group and glycerol

Question 21

structure of phospholipids

Answer 21

• hydrophilic head due to negative charge on phosphate group
• attracts water and repels fats as it is charged
• the fatty acid chain is not charged - hydrophobic tail and it repels water but will mix with fats

Question 22

properties of phospholipids

Answer 22

• have two charged regions so they are polar
• in water, they are positioned so that the heads are exposed to water and the tails are not
• forms a phospholipid bilayer membrane structure which makes up the plasma membrane around cells