1.1 - Biological Compounds

Question 1

name the 4 inorganic ions in living organisms

Answer 1

magnesium, phosphate, calcium, iron

Question 2

what is the role of Mg2+ in plants ?

Answer 2

used to produce chlorophyll

Question 3

what is the role of FE2+ in animals ?

Answer 3

component of haemoglobin and is involed in the transport of oxygen

Question 4

what is the role of PO4 3- in living organisms?

Answer 4

strengthen tissues such as bones, teeth in animals and in cell walls in plants

Question 5

why is water a polar molecule ?

Answer 5

unequal distribution of charge across the molecule
O is delta negative the H
O attracts electrons more strongly than H

Question 6

describe H+ bonding between water molecules

Answer 6

weak intermolecular forces of attraction from between a lone pair of a delta negative O and a delta positive H on an adjacent molecule

Question 7

what is a metabolite ?

Answer 7

a molecule formed or used in a metabolic reaction

Question 8

how is water a metabolite ?

Answer 8

• H2O is a reactant in photosynthesis and hydrolysis reactions
• H2O is a product in aerobic respiration and condensation reactions

Question 9

why is water’s high specific heat capacity important for organisms ?

Answer 9

• acts a temperature buffer, enabling endotherms to resist fluctuations in core temperature
• maintain optimum enzyme activity

Question 10

why is water’s high latent heat of evaporation important for organisms?

Answer 10

• when water evaporates, it has a cooling effect
• this is important in homeostasis: organisms can lose heat through sweating or panting

Question 11

why is water an important solvent for organisms ?

Answer 11

• water is polar
• it enables chemical reactions to take place within cells
• the transport of materials in the plasma
• removal of metabolic waste

Question 12

why does water have high surface tension ?

Answer 12

cohesion of water molecules at the surface of the water

Question 13

why is a high surface tension important for organisms ?

Answer 13

• enables transport of water and nutrients through plants stems and small blood vessels in the body
• allows small insects to walk on the water surface

Question 14

what is a monosaccharide ?

Answer 14

• simple sugar
  general formula = Cn(H20)n

Question 15

give some examples of monosaccharides

Answer 15

• ribose
• deoxyribose
• α and β glucose
• fructose
• galactose

Question 16

what is the difference between α and β glucose

Answer 16

• the orientation of the hydroxyl group
• (ABBA) alpha below beta above

Question 17

what is the name of the bond formed when two monosaccharides bond?

Answer 17

glycosidic bond

Question 18

what is a disaccharide ?

Answer 18

• molecule formed by condensation reaction between to monosaccharides
• held together by a glycosidic bond
  general formula = C12H22O11

Question 19

give some examples of disaccharides and their monosaccharide constituents

Answer 19

glucose + fructose –> sucrose
glucose + glucose –> maltose
glucose + galactose –> lactose

Question 20

what is a polysaccharide ?

Answer 20

a polymer of monosaccharides, formed by many condensation reactions

Question 21

give some examples of polysaccharides

Answer 21

• starch
• glycogen
• cellulose
• chitin

Question 22

what is the function of starch?

Answer 22

energy storage in plants

Question 23

describe the structure of starch

Answer 23

• polymer of two α glucose monomers
• two forms: amylose and amylopectin
• amylose : 1-4 glycosidic bonds (unbranched)
• amylopectin: 1-4 and 1-6 glycosidic bonds (branched)

Question 24

what is the function of gylcogen ?

Answer 24

energy storage in animals

Question 25

how does the structure of glycogen relate to its function ?

Answer 25

it is highly branched enabling the rapid hydrolysis of glucose molecules

Question 26

describe the structure and function of cellulose

Answer 26

• main component of cell walls in plants (structural function)
• consists of β glucose molecules joined by 1-4 glycosidic bonds (unbranched
• alternate glucose molecules rotated 180° allowing hydrogen bonds between parallel chains, forming microfibrils

Question 27

describe the structure and function of chitin

Answer 27

• found in exoskeletons of insect and crustaceans as well as fungal cell walls (structural function)
• consists of β glucose molecules with amino acid side chains, joined by 1-4 glycosidic bonds
• alternate glucose molecules rotated 180° allowing hydrogen bonds between parallel chains, forming microfibrils

Question 28

how is a triglyceride formed ?

Answer 28

one molecule of glycerol forms ester bonds with three fatty acids via condensation reactions

Question 29

relate the structure of triglycerides to their function

Answer 29

• high energy storage in H+ bonds
• insoluble hydrocarbon chain - used for waterproofing
• slow conductor of heat - thermal insulation
• less dense than water - used for buoyancy of aquatic animals

Question 30

what is a phospholipid ?

Answer 30

formed by condensation of one glycerol molecule, two fatty acids and a phosphate group

Question 31

relate the structure of phospholipids to their function

Answer 31

• fatty acids are hydrophobic
• phosphate head is hydrophilic
• forms a phospholipid bilayer in water - component of cell membranes
• tails splay outwards - waterproofing

Question 32

what is the difference between saturated and unsaturated fats ?

Answer 32

• saturated fats have no C=C bonds, are solid at room temp due to strong intermolecular forces
• unsaturated fats have one or more C=C bonds, are liquid at room temp due to weak intermolecular forces

Question 33

what is meant by a low density lipoprotein (LDL)?

Answer 33

• combination of triglycerides from saturated fats and protein
• blocks receptor sites, reducing cholesterol absorption
• know as ‘bad’ lipoproteins

Question 34

how do LDLs contribute to the risk of CVD ?

Answer 34

high blood cholesterol level caused by LDLs leads to the formation of atheromas

Question 35

describe the general structure of an amino acid (draw it )

Answer 35

• amine group
• variable R group
• carboxyl group
• H atom
• central carbon