AQA AS LEVEL BIOLOGY EXAM SCRIPT
QUESTIONS WITH ANSWERS GRADED A+
✔✔properties of starch and glycogen as energy stores? - ✔✔-insoluble, doesn't affect
water potential, cell won't shrink or burst
-coiled, compact, fits inside cells better
-branched/chained, easy to break down, glucose removed from the end
✔✔endoplasmic reticulum? - ✔✔rough- has ribosomes ,protein synthesis, process and
package
smooth- makes lipids and carbs
✔✔golgi apparatus? - ✔✔processes and packages proteins
into vesicles
digestive enzymes placed into lysozomes, vesicles with membranes
✔✔structure of cellulose? - ✔✔-beta glucose arranged in straight chain (each
alternative beta glucose rotated 180°)
-many cellulose chains are cross linked by hydrogen bonds, form microfibrils
-microfibrils crosslinked to make macrofibrils
-hydrogen bonds are strong together, hard to break,makes cellulose strong
-forms cell wall structure
✔✔mitochondria? - ✔✔site of respiration, produces ATP which releases energy
cristae- inner membrane has large surface area so more metabolic enzymes can attach
matrix- middle liquid
✔✔test for starch? - ✔✔iodine brown to blue/black
✔✔chloroplast structure? - ✔✔absorbs light energy for photosynthesis to produce
glucose
double membrane
thylakoid disks stack into granum
thylakoid surrounded by stroma fluid
large surface area
✔✔test for reducing sugars - ✔✔heat with benedicts, turns brick red
✔✔vacuole - ✔✔surrounded by membrane called tonoplast
contains cell sap
keeps cell turgid
pushes chloroplasts to surface
✔✔test for non reducing sugar? - ✔✔-heat with benedicts, no change
-add dilute hcl (hydrolyses glycosidic bond)
,-add sodium hydrogen carbonate to neutralise
-heat with benedicts, will turn brick red
✔✔structure of bacteria? - ✔✔circular DNA and plasmids
no membrane bound organelles
smaller ribosomes
cell wall made of murein
some have slime capsule (protect from phagocytosis) and flagella (movement)
✔✔types of proteins? - ✔✔globular and fibrous
✔✔structure of virus? - ✔✔DNA or RNA
if RNA, contains reverse transcriptase enzyme to convert it into DNA
capsid
phospholipid membrane
attachment proteins to identify and attach to host
✔✔what are globular proteins? - ✔✔have a specific 3d shape, soluble eg. haemoglobin
✔✔how does a virus infect their host cell? - ✔✔uses attachment protein to attach
send in DNA capsid which uses cell to make virus components
producing copies and destroying host cell
✔✔what are fibrous proteins? - ✔✔insoluble, inflexible and strong eg. keratin
✔✔how do amino acids differ? - ✔✔have different r groups
✔✔what is a chromosome? - ✔✔coiled DNA
formed during interphase
made of 2 sister chromatids joined by centromere
2 copies of same DNA molecule
✔✔what is a homologous pair of chromosomes? - ✔✔1 maternal 1 paternal
same genes but different alleles
✔✔how are amino acids joined? - ✔✔condensation reaction between carboxyl group
and amine group. leaves bond between carbon and nitrogen, DIPEPTIDE
✔✔primary structure of a protein? - ✔✔sequence of AA, polypeptide chain. change in
sequence, bonds will be formed in different places in secondary.
✔✔secondary structure? - ✔✔primary structure coils to form an alpha helix, hydrogen
bonds form between amino acids
, ✔✔tertiary structure? - ✔✔secondary structure folds again to form final 3d shape, held
by ionic/hydrogen/disulfide bonds
✔✔quarternary structure? - ✔✔more than one polypeptide chain, non protein can be
involved
✔✔quarternary structure examples? - ✔✔haemoglobin, antibodies, collagen
✔✔collagen structure? - ✔✔-strong
-primary structure glycine
-secondary tight coil
-tertiary coils again
-quarternary three chains wrapped like rope
✔✔protein test? - ✔✔biruet reagent, turns purple
✔✔what is an enzyme? - ✔✔biological catalyst
speeds up reaction without being used up
lowers activation energy
✔✔what makes an enzyme specific? - ✔✔specific active site, only complimentary
substrates can bind and form enzyme substrate complexes
✔✔lock and key model? - ✔✔active site is rigid, only exactly complimentary substrates
fit
✔✔induced fit model? - ✔✔shape of active site changes slightly so substrate fits exactly
forming ES complex
✔✔affect of substrate concentration on enzyme activity? - ✔✔more substrate, more
chance of successful collisions, ES complex, increase rate
increases until all enzymes are saturated
✔✔affect of enzyme concentration on enzyme activity? - ✔✔more enzymes, more
successful reactions, ES complexes
continues until all the substrates are used up
✔✔affect of temperature on enzyme activity? - ✔✔as temp increases, kinetic energy
increases, molecules move faster
more collisions, more ES complexes
carries on until optimum
after optimum, tertiary bonds break
lose active site shape
no longer complimentary
denatured
QUESTIONS WITH ANSWERS GRADED A+
✔✔properties of starch and glycogen as energy stores? - ✔✔-insoluble, doesn't affect
water potential, cell won't shrink or burst
-coiled, compact, fits inside cells better
-branched/chained, easy to break down, glucose removed from the end
✔✔endoplasmic reticulum? - ✔✔rough- has ribosomes ,protein synthesis, process and
package
smooth- makes lipids and carbs
✔✔golgi apparatus? - ✔✔processes and packages proteins
into vesicles
digestive enzymes placed into lysozomes, vesicles with membranes
✔✔structure of cellulose? - ✔✔-beta glucose arranged in straight chain (each
alternative beta glucose rotated 180°)
-many cellulose chains are cross linked by hydrogen bonds, form microfibrils
-microfibrils crosslinked to make macrofibrils
-hydrogen bonds are strong together, hard to break,makes cellulose strong
-forms cell wall structure
✔✔mitochondria? - ✔✔site of respiration, produces ATP which releases energy
cristae- inner membrane has large surface area so more metabolic enzymes can attach
matrix- middle liquid
✔✔test for starch? - ✔✔iodine brown to blue/black
✔✔chloroplast structure? - ✔✔absorbs light energy for photosynthesis to produce
glucose
double membrane
thylakoid disks stack into granum
thylakoid surrounded by stroma fluid
large surface area
✔✔test for reducing sugars - ✔✔heat with benedicts, turns brick red
✔✔vacuole - ✔✔surrounded by membrane called tonoplast
contains cell sap
keeps cell turgid
pushes chloroplasts to surface
✔✔test for non reducing sugar? - ✔✔-heat with benedicts, no change
-add dilute hcl (hydrolyses glycosidic bond)
,-add sodium hydrogen carbonate to neutralise
-heat with benedicts, will turn brick red
✔✔structure of bacteria? - ✔✔circular DNA and plasmids
no membrane bound organelles
smaller ribosomes
cell wall made of murein
some have slime capsule (protect from phagocytosis) and flagella (movement)
✔✔types of proteins? - ✔✔globular and fibrous
✔✔structure of virus? - ✔✔DNA or RNA
if RNA, contains reverse transcriptase enzyme to convert it into DNA
capsid
phospholipid membrane
attachment proteins to identify and attach to host
✔✔what are globular proteins? - ✔✔have a specific 3d shape, soluble eg. haemoglobin
✔✔how does a virus infect their host cell? - ✔✔uses attachment protein to attach
send in DNA capsid which uses cell to make virus components
producing copies and destroying host cell
✔✔what are fibrous proteins? - ✔✔insoluble, inflexible and strong eg. keratin
✔✔how do amino acids differ? - ✔✔have different r groups
✔✔what is a chromosome? - ✔✔coiled DNA
formed during interphase
made of 2 sister chromatids joined by centromere
2 copies of same DNA molecule
✔✔what is a homologous pair of chromosomes? - ✔✔1 maternal 1 paternal
same genes but different alleles
✔✔how are amino acids joined? - ✔✔condensation reaction between carboxyl group
and amine group. leaves bond between carbon and nitrogen, DIPEPTIDE
✔✔primary structure of a protein? - ✔✔sequence of AA, polypeptide chain. change in
sequence, bonds will be formed in different places in secondary.
✔✔secondary structure? - ✔✔primary structure coils to form an alpha helix, hydrogen
bonds form between amino acids
, ✔✔tertiary structure? - ✔✔secondary structure folds again to form final 3d shape, held
by ionic/hydrogen/disulfide bonds
✔✔quarternary structure? - ✔✔more than one polypeptide chain, non protein can be
involved
✔✔quarternary structure examples? - ✔✔haemoglobin, antibodies, collagen
✔✔collagen structure? - ✔✔-strong
-primary structure glycine
-secondary tight coil
-tertiary coils again
-quarternary three chains wrapped like rope
✔✔protein test? - ✔✔biruet reagent, turns purple
✔✔what is an enzyme? - ✔✔biological catalyst
speeds up reaction without being used up
lowers activation energy
✔✔what makes an enzyme specific? - ✔✔specific active site, only complimentary
substrates can bind and form enzyme substrate complexes
✔✔lock and key model? - ✔✔active site is rigid, only exactly complimentary substrates
fit
✔✔induced fit model? - ✔✔shape of active site changes slightly so substrate fits exactly
forming ES complex
✔✔affect of substrate concentration on enzyme activity? - ✔✔more substrate, more
chance of successful collisions, ES complex, increase rate
increases until all enzymes are saturated
✔✔affect of enzyme concentration on enzyme activity? - ✔✔more enzymes, more
successful reactions, ES complexes
continues until all the substrates are used up
✔✔affect of temperature on enzyme activity? - ✔✔as temp increases, kinetic energy
increases, molecules move faster
more collisions, more ES complexes
carries on until optimum
after optimum, tertiary bonds break
lose active site shape
no longer complimentary
denatured
