Unit 6 Biology ISA

Investigating Chlorophyll and Other pigments

  • Method
  • Comparing photosynthetic pigments in leaves
  • Chromatography
  • Reference to Photosynthesis 
HideShow resource information
  • 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 


1 of 5

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

2 of 5

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

3 of 5

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

4 of 5

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 

5 of 5

Comments

Loveleen

what would be the null hypothesis and the conclusion?

mary

have you done the most recent isa or is this just study materials?

mary

have you done the most recent isa or is this just study materials?

mary

and if this is the isa which is the stastical test you used

mary

and if this is the isa which is the stastical test you used

mary

and if this is the isa which is the stastical test you used

yasmin shah

is this what comes up on the isa?

ank

what kind of questions come up in section b (the exam part) of the isa? thanks :D

Tasmia Ahmed

Hey just wondered if anyone can help with what comes up in section B and what to revise for? :)

Thanks :D 

Tasmia Ahmed

ank wrote:

hey if you've done the isa would you be able to tell me what comes up? thanks :D

flower123

Loveleen wrote:

what would be the null hypothesis and the conclusion?

sorry if this is a bit late

the null hypothesis will b that there is no relationship between whatever your trying to find, and in conclution you just acceot the null hypothesis if there is overlap and reject if no overlap in the error bars and you also hve to mention that there is less than 5% probability that the statistical difference is due to chance


flower123

mary wrote:

and if this is the isa which is the stastical test you used

sorry if this is a bit late

you use standard error and 95% confidence limit
flower123

Tasmia Ahmed wrote:

Hey just wondered if anyone can help with what comes up in section B and what to revise for? :)

Thanks :D 

sorry if this is a bit late

for section B revise stuff on quadrats, transects, limiting factors, light dependent reaction

flower123

thank you so much for these notes =)

HelloKitty

does anyone know anything about the ISA practical involving yeast?

what things should we prepare for / revise?

thanks

Paulina

Hey, I'm wondering if in section B will be anything on ecology and populations, like succession? any other info about section B?

Thank you :)

Dima Borysov

anyone want to hit me up with some more hints for the isa?

would be much appreciated :)

Sadiya' :]

Aww thanks so much for this ISA info... Much appreciated ! :) **

Bina

Hey has anyone done the paper yet? What comes up in section B? Thanks! :) 

chax

What is asked in section B - what do i need to know?>

chax

What is asked in section B - what do i need to know?>

Charlotte

Are there any random questions that come up that wouldnt be in the textbook? Are there any hard questions? Thanks in advance

Bina

When is everyones ISA? Mine is tomorrow..any help would be appreciated! 

tanya mcentee

Hey Bina how was the ISA, could you tell me some specific questions for section b?

Alice

Rf = retardation factor! Not relative front

javeria

Hey, i've got the ISA tomorrow was wondering if there was anything anyone would recommend i should particularly research on?

james

anyone know the type of questions they ask on section B

james

javeria wrote:

Hey, i've got the ISA tomorrow was wondering if there was anything anyone would recommend i should particularly research on?

what kind of questions came up on section B if you dont mind me asking 

izm

Hi was wondering if anyone had any information on the practical involving Yeast? :)

Similar Biology resources:

See all Biology resources »See all resources »