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BIOLOGY
REQUIRED PRACTICALS
8 - DEHYDROGENASE ACTIVITY
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Created by
Jasmine Singh
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Cards (7)
AIM?
investigate effect of named
factor
on
rate
of
dehydrogenase activity
in
chloroplast extracts
->
temperature
/
light intensity
WHY DOES THIS EXPERIMENT WORK?
in
LDR
,
NADP
reduced
to
NADPH
by
gaining electrons
and using
dehydrogenase
as a
catalyst
->
DCPIP
accepts electrons
instead (turns from
blue
to
colourless
)
KEY PRACTICAL STEPS?
ice water bath
to prevent
breakdown
of
chloroplasts
by
enzymes
colorimeter
more
accurate
as not
subjective
measure time
until
absorbance
reached
end point
of
colour change
(check at
2 minute intervals
)
IV?
temperature
/
light intensity
(
proportional
to
1/d^2
)
DV?
time taken
for
DCPIP
to
decolourise
(
rate of LDR
proportional
to
1/t
)
CVs?
wavelength
of
light
volume
of
DCPIP
concentration
of
DCPIP
type
of
plant
size
of
plant
RISK?
DCPIP
is an
irritant
,
eye
protection
