AQA A-level Biology paper 1
large molecules often contain carbon.
why? - Answer-they can readily form
bonds with other carbon atoms. this
forms a 'backbone'. other atoms can
then attach.
describe benedicts test for reducing
sugars - Answer-add equal volumes of
the sugar sample and benedicts
reagent.
heat the mixture in a water bath for 5
minutes.
brick red precipitate will form.
,what is a reducing sugar? - Answer-a
sugar that can reduce (give electrons
to) another chemical.
describe the benedicts test for non
reducing sugars - Answer-with food
sample, add an equal volume of dilute
hydrochloric acid in a test tube.
place test tube in water bath for 5
mins.
add sodium hydrogencarbonate
solution.
heat resulting solution with an equal
volume of benedicts. solution for 5
minutes.
turns orange/brown.
,what does dilute hydrochloric acid do
in the benedicts test for non reducing
sugars? - Answer-it hydrolyses any
disaccharide into monosaccharides,
thus also forming reducing sugars.
describe the structure of starch -
Answer-chains of alpha glucose
some chains are branched=
amylopetcin
some chains are coiled= amylose
what purpose does the structure of
amylose serve? - Answer-makes the
molecule compact so it is stored more
easily.
, what purpose does the structure of
amylopectin serve? - Answer-more
surface area for enzymes to work on,
thus glucose molecules can be released
at a much quicker rate.
how is the structure of starch suited to
its function? - Answer-1. starch is
insolube so it doesnt affect water
potential
2. it is large enough that it doesnt
diffuse out of cells
3. compact enough so that a lot of it
can be stored in a small space
4. branched= each end can
simultaneously be acted on by
enzymes, so glucose is quickly released
large molecules often contain carbon.
why? - Answer-they can readily form
bonds with other carbon atoms. this
forms a 'backbone'. other atoms can
then attach.
describe benedicts test for reducing
sugars - Answer-add equal volumes of
the sugar sample and benedicts
reagent.
heat the mixture in a water bath for 5
minutes.
brick red precipitate will form.
,what is a reducing sugar? - Answer-a
sugar that can reduce (give electrons
to) another chemical.
describe the benedicts test for non
reducing sugars - Answer-with food
sample, add an equal volume of dilute
hydrochloric acid in a test tube.
place test tube in water bath for 5
mins.
add sodium hydrogencarbonate
solution.
heat resulting solution with an equal
volume of benedicts. solution for 5
minutes.
turns orange/brown.
,what does dilute hydrochloric acid do
in the benedicts test for non reducing
sugars? - Answer-it hydrolyses any
disaccharide into monosaccharides,
thus also forming reducing sugars.
describe the structure of starch -
Answer-chains of alpha glucose
some chains are branched=
amylopetcin
some chains are coiled= amylose
what purpose does the structure of
amylose serve? - Answer-makes the
molecule compact so it is stored more
easily.
, what purpose does the structure of
amylopectin serve? - Answer-more
surface area for enzymes to work on,
thus glucose molecules can be released
at a much quicker rate.
how is the structure of starch suited to
its function? - Answer-1. starch is
insolube so it doesnt affect water
potential
2. it is large enough that it doesnt
diffuse out of cells
3. compact enough so that a lot of it
can be stored in a small space
4. branched= each end can
simultaneously be acted on by
enzymes, so glucose is quickly released
