2.3 CARBOHYDRATES AND LIPIDS

Question 1

Macromolecules and subunits (monomers)

Answer 1

Protein/ polypeptides=
Amino acid

Carbohydrates/ polysaccharide=
Monosaccharide

Lipids/ triglyceride=
3 fatty acids + glycerol

Nucleic acid=
Nucleotides

Question 2

Functions of lipids

Answer 2

Energy storage
Heat insulator due to poor conduction (non-polar)
–> blubber for artic animals
Buoyancy: float as fat is less dense than water

Question 3

Energy storage overview

Answer 3

Lipids are more suitable for long term energy storage in humans than carbohydrates

Question 4

Reasons for using lipid as energy storage

Answer 4

Quantity of E released in cell respiration per gram is more than double than carbs (16 kJ <39kJ)
–> half as much body mass is needed for same Q of E

Lipids are six times more efficient

Lipids have secondary roles that carbs don’t: heat insulators

Question 5

Reasons for using carbohydrates/ glycogen as energy

Answer 5

Glycogen for short term E storage as it is rapidly broken down and easily transported by the blood
whilst fats in adipose tissue (lipids) cannot be mobilised as quickly

Glucose can do both anaerobic and aerobic respiration but lipids can only respire aerobically

Question 6

Monosaccharide

Answer 6

Glucose
Blood sugar; made by plants

Galactose
Dairy products; less sweet

Fructose
Very sweet; honey

Question 7

Disaccharides

Answer 7

Maltose
2 glucose M; malt sugar

Lactose
Galactose + glucose; milk

Sucrose
Sugarcane; glucose+ fructose

Question 8

Polysaccharides

Answer 8

Starch (made of glucose)
Storage E in plants

Glycogen ( when there is too much glucose)
Storage E in animals

Cellulose
Plant cell walls

Question 9

Function of glucose in animals

Answer 9

A source

Of energy

Question 10

Function of lactose in animals

Answer 10

sugar in milk of mammals
Energy source
To young

Question 11

Function of glycogen in animals

Answer 11

Use sore short term E storage in the liver

Question 12

Function of fructose in plants

Answer 12

Source of E (honey)

Question 13

Function of sucrose in plants

Answer 13

Transport and store E (sugar cane)

Question 14

Function of cellulose in plants

Answer 14

Fibres arranged in layers

Provide strength in cell wall

Question 15

Fatty acids

Answer 15

Saturated: single bonds between all C atoms

Unsaturated: at least one double bond

Polyunsaturated: more than one double bond

Question 16

Unsaturated fatty acids

CIS

Answer 16

H atoms are always on the same side of the 2 C aroma that are double bonded
Bend in hydrocarbon chain at double bond
Bad for packing regularly
Lower melting point
Usually liquid ART

Question 17

Unsaturated fatty acids

TRANS

Answer 17

H on opp sides 
No bend 
Higher melting point 
Solid ART
Produced artificially: margarine/ processed foods

Question 18

Carbohydrates

Answer 18

Monosaccharides monomers are linked together by condensation reaction

Disaccharide and polysaccharide polymers

Question 19

Glucose M

Answer 19

Hexagon

Question 20

Ribose M

Answer 20

Pentagon

Question 21

Cellulose

Answer 21

Straight
Unbranched polymer of beta and D glucose

Forms cross links with hydrogen bonds

Very strong

Question 22

Starch

Answer 22

Helical shape
Polymer of alpha and D glucose M

Amylose: 1,4 links unbranched
Amylopectin: some 1,6 links branched

Plants use it to store glucose

Question 23

Glucogen

Answer 23

Branches polymer of alpha and D glucose

More 1,6 links more branched than amylopectin

Mammals use it to store glucose in liver / muscle cells

INSOLUBLE

if glucose is stored, water would enter cells, making them burst because glucose is soluble

Question 24

Links between glucose sub units

Answer 24

1,4 bonds

Some 1,6

Question 25

Lipids

Answer 25

Triglycerides

Phospholipids

Steroids

Question 26

Triglycerides

Answer 26

3 fatty acids and I glycerol hay condensation

3 hydrocarbon tails

Fats/
Oil

Question 27

Phospholipids

Answer 27

2 fatty acids linked to glycerol and phosphate group
Partly hydrophobic
Form membranes

Question 28

Steroids

Answer 28

Four fuses rings 
Cholesterol 
Estrogen 
Progesterone 
Testosterone