AQA A-Level Biology Exam Questions With
Complete Solutions
polymer
long molecules formed from combinations of many monomers joined together
condensation reaction
a chemical reaction in which two or more molecules join and produces one water
molecule
hydrolysis reaction
A chemical reaction that breaks apart a larger molecule by adding a molecule of
water
isomers
Compounds with the same chemical formulae but different structures.
carbohydrates
compounds made from carbon, hydrogen and oxygen (monosaccharides,
disaccharides and polysaccharides), important energy store
monosaccharide
simple sugars (glucose, fructose, galactose)
disaccharide
two monosaccharides joined together by a glycosidic bond
polysaccharide
many sugar units joined by a glycosidic bond
maltose
α glucose + α glucose
lactose
glucose + galactose
sucrose
glucose + fructose
where is lactose found?
milk
where is maltose found?
germinating seeds
, where is sucrose found?
table sugar
cellulose
polymer of β glucose
starch
polymer of α glucose (amylose + amylopectin)
what is the structure of cellulose?
long, unbranched chains of β glucose, insoluble
where is cellulose found?
plant cell walls
why is cellulose strong?
chains linked by h bonds form microfibrils giving high tensile strength to prevent
osmotic lysis
what is the structure of starch?
long, highly-branched, compact helix and insluble
where is starch found?
energy stores in plants
glycogen
storage form of glucose in animals, compact, highly-branched structure
limits of the Benedict's test
isn't specific or sensitive
what is the test for reducing sugars?
Benedict's test
what colour will the solution be in the presence of reducing sugars?
green → red (nearer red, higher conc reducing sugar)
what is the test for starch?
iodine test
if starch is present, what colour will the iodine be?
orange → blue-black
covalent bond
a chemical bond in which two atoms share a pair of electrons
ionic bond
the bond between two oppositely charged ions
hydrogen bond
Complete Solutions
polymer
long molecules formed from combinations of many monomers joined together
condensation reaction
a chemical reaction in which two or more molecules join and produces one water
molecule
hydrolysis reaction
A chemical reaction that breaks apart a larger molecule by adding a molecule of
water
isomers
Compounds with the same chemical formulae but different structures.
carbohydrates
compounds made from carbon, hydrogen and oxygen (monosaccharides,
disaccharides and polysaccharides), important energy store
monosaccharide
simple sugars (glucose, fructose, galactose)
disaccharide
two monosaccharides joined together by a glycosidic bond
polysaccharide
many sugar units joined by a glycosidic bond
maltose
α glucose + α glucose
lactose
glucose + galactose
sucrose
glucose + fructose
where is lactose found?
milk
where is maltose found?
germinating seeds
, where is sucrose found?
table sugar
cellulose
polymer of β glucose
starch
polymer of α glucose (amylose + amylopectin)
what is the structure of cellulose?
long, unbranched chains of β glucose, insoluble
where is cellulose found?
plant cell walls
why is cellulose strong?
chains linked by h bonds form microfibrils giving high tensile strength to prevent
osmotic lysis
what is the structure of starch?
long, highly-branched, compact helix and insluble
where is starch found?
energy stores in plants
glycogen
storage form of glucose in animals, compact, highly-branched structure
limits of the Benedict's test
isn't specific or sensitive
what is the test for reducing sugars?
Benedict's test
what colour will the solution be in the presence of reducing sugars?
green → red (nearer red, higher conc reducing sugar)
what is the test for starch?
iodine test
if starch is present, what colour will the iodine be?
orange → blue-black
covalent bond
a chemical bond in which two atoms share a pair of electrons
ionic bond
the bond between two oppositely charged ions
hydrogen bond
