Unit 6 Biology ISA
Investigating Chlorophyll and Other pigments
- Method
- Comparing photosynthetic pigments in leaves
- Chromatography
- Reference to Photosynthesis
- Created by: Joanna
- Created on: 11-10-11 15:42
Method
- Independent variable - type of leaf
- Dependent variable - RF value (using chromatography)
Chromatography
Identify different colours of dyes, inks and pigments
- separate out different pigments from leaf
-some pigments are more soluble in solvent : travel furthest
-mark a colour spot of leaf using a rod : shouldn't be below level of solvent so that it doesn't dissolve
-don't move the chromatogram so that it will not touch the side of boiling tube - pigments may run off edge
-mark position of solvent asa chromatgoram stopped running - don't leave solvent too long - evaporate
- middle pigment marked - middle value / an average - allow comparison / standardisation
-calculate relative front value using distance moved by pigment / distance moved by solvent front
-RF value <1
Comparing photosynthetic pigments in leaves
2 different species of leaves
cut out same number and size of leaf discs
same volume of ethanol (solvent)
same length of time
filter / centrifuge photosynthetic pigments
pigment- place on origin on chromatography paper and leave to run
Chromatogram 1 | Chromatogram 2
calculate RF value and compare
statistical test? looking for a significant different in RF values
use standard error and 95% confidence limits
Chromatography
identify different colours of dyes, pigments and inks
how does it work?
separate out different pigments from leaf
some pigments are more soluble - travel the furthest
some pigments are insoluble - don't travel as far
mark position of the origin in pencil - don't use ink
spot shouldn't be below level of solvent so it wouldn't dissolve
not move the chromatogram while running - so it wont touch side of boiling tubes & pigments wont run off the edge
mark position of the solvent front as soon as chromatogram stopped running - solvent may evaporate
relative front = distance from origin to spot / distance from origin to solvent front
middle of the pigment spot is marked - average / allows comparison + standardisation
Photosynthesis
2 stages: light dependent and light independent
light dependent - thylakoid membranes | light independent [calvin cycle] - stroma
products of LD - reduced NADP, ATP + oxygen
products of LI - NADP / ADP / triose phosphate + useful organic substances e.g. glucose
how to measure rate of photosynthesis:
aquatic plant e.g. elodea -in water as oxygen less dense than h20
use photosynthometer - count # of bubbles
read scale + work out volume of syringe (pie r squared x length)
rate = volume of oxygen / time
controlled factors:
thermostatically controlled water bath - maintain constant temperature
potassium hydrogencarbonate - provide source of carbon dioxide
plant left in dark at 1st so it doesn't photosynthesis
Photosynthesis - limiting factors
Effect of light intensity
As light intensity increases, rate of photosynthesis increaes - above compensation point - more oxygen until reached the light saturation point, light no longer becomes the limiting factor and so the curve plateaus
Reference to reaction of photosynthesis - why?
More light - more photolysis of water - formation of protons and electrons - during light harvesting so more ATP and NADPH produced
Temperature doesn't affect rate of light dependent reaction as it is a photochemical reaction + doesn't use enzymes
Temperature affects rate of light independent reaction as it is a metabolic reaction + use enzymes e.g. ribulose bisphosphate carboxylase - each enzymes have optimum level
Action spectrum - shows rate of photosynthesis at different wavelengths of light
Absorption spectrum - shows absorption of different wavelengths of light by different photosynthetic pigments
Green light - not strongly absorbed but reflected
Red light strongly absorbed but white light is very strongly absorbed as it contains all the different wavelengths of light
Variegated leaves don't grow as well - contains less chloroplasts / less chlorophyll / less electrons emitted and also need proteins e.g. nitrates
Related discussions on The Student Room
- 7 weeks of revision...for medicine...my timetable »
- Over 500 questions on AQA Bio Unit 4 + Current Spec and old Spec papers + MS! »
- need urgent advice ,messed up bad »
- BTEC Level 3 in applied science »
- Edexcel IAL BIOLOGY JANUARY 2024 »
- Biology rate of reaction question »
- Pharmacy/a levels »
- any tips for taking/retaking edexcel biology ial unit 6 (practicals)? »
- GCSE Biology Study Group 2022-2023 »
- BTEC Level 3 Applied Science Unit 1 May 2022 Exams »
Comments
Report
Report
Report
Report
Report
Report
Report
Report
Report
Report
Report
Report
Report
Report
Report
Report
Report
Report
Report
Report
Report
Report
Report
Report
Report
Report
Report
Report
Report