Photosynthesis

Question 1

What are the three main pigment groups?

Answer 1

chlorophylls (Chl), carotenoids and phycobilins

Question 2

Give 3 examples of parameters who can be calculated from fluorenscence measurements.

Answer 2

relative electron transport rate (rETR)
constitutive heat dissipation (NO)
non-photochemical quenching (NPQ)
light saturation parameter (Ek)

Question 3

How high (in%) are the proportions of quenching parameters in optimum conditions?

Answer 3

photochemistry: 25-30%
constitutive heat dissipation: 70%
non-photochemical quenching: 1-5%

Question 4

If you sum up all quenching parameter values how high will the outcome be?

Answer 4

1 or 100%

Question 5

Where does 95% of the in-vivo Chla fluorescence originates from at room temperature?

Answer 5

PS II

Question 6

How can you make the fluorescence of PS I visible?

Answer 6

low temperaters (77 kelvin)

Question 7

Why can you see PSI fluorescence only at low temperature?

Answer 7

room temperature: all energy is used for photochemistry because PSI is very effective
low temperature: photochemical processes have stopped and excess energy is released as fluorescence

Question 8

How can you roughly destinguish between taxa/pigment groups by using fluorescence measurements (FluroCam, 77K)?

Answer 8

ratio of PSII : PSI (e.g. Chlorophyta 0,5)

fluorescence emission wavelength

Question 9

Name two today widely used fluormeters.

Answer 9

pulse amplitude modulation (PAM) fluormeter

fasr repetition rate fluormeter (FRRf)

Question 10

Which instruments use single-turnover and which use mutiple-turnover saturation pulses?

Answer 10

PAM: MT
FluorCam: MT
FRRf: ST and MT

Question 11

Why are there differences in photosynthetic proterties along a lamina of kelp?

Answer 11

lamina may adapt different postures through the water column
lamina’s orientation differs
spatial distribution of the downwelling irradiance along the lamina
Specific geometric
arrangements of the lamina may affect profoundly the absorption of light, such as folding, curves or
the straight lamina alignment

Question 12

What do the spatial differences concerning photosynthetic properties along a lamina show?

Answer 12

tissues sticking upward tend to receive higher downwelling irradiance other
underlying tissues from the same lamina receive lower downwelling irradiance

Question 13

What kind of samples can be examined with the Handy FluorCam?

Answer 13

macroscopic samples such as leaves or cut

samples in a petri dish

Question 14

What kind of measurements can be done with the fluorescence kinetic microscope?

Answer 14

FKM enables imaging measurements of photosynthetically active
organisms, and is specifically designed to investigate microscopic cells and sub-cellular structures

Question 15

What informations does the 77K-spectrometer provide?

Answer 15

provides detection of the absolute

optical spectra from internal pigments, photosystems, and their composition

Question 16

What are the excitation spectra used for?

Answer 16

compare actual intensity at each excitation wavelength, which in turn can be used to assess which
pigments dominate in fluorescence contribution

Question 17

What does a low Ek-value mean?

Answer 17

alga is low light adapted

Question 18

If the Ek decreases with rising temperature, what does this tell you about the sample?

Answer 18

higher Ek = higher irradiance needed to be light saturated

the sample is stressed in high temperature

Question 19

Name 3 cons on the Diving PAM in comparison to the FluorCam.

Answer 19

PAM: light source further away and is operated by hand, high human error, no decent temperature control, no decent dark-acclimation possible

Question 20

Which instrument is the most precise: Diving PAM, FRRf and Fluor Cam. Why?

Answer 20

FRRf
most sensitive to fluorescence
real dark incubation possible
temperature controlled
computer controlled protocoll
BUT: not useful for macroalgae analysis

Question 21

Which instruments that we used can be used for analysis for macroalgae and which for microalgae?

Answer 21

macroalgae: PAM, FluorCam
microalgae: RFFf, fluorescence kintecs microscope (FKM)

Question 22

What does the maximum quantum yield tells you about your sample?

Answer 22

maximum photochemical efficiency of open RCIIs (all Qa are in a fully oxidised state) (measured with one light pulse after dark acclimation)
In basic
terms the quantum yield (F) can be described as the
ratio of product output to gathered quanta:
mol product out/mol quanta in
–> fraction of photons used for photochemical reactions (=ratio)

Question 23

Can you compare samples from different pigment groups without mentioning the species?

Answer 23

no
there are big differences between species in the same PG
different pigment composition, different physiological properties, different ecological background

Question 24

What differences concerning photosynthetic properties do you find along a kelp lamina?

Answer 24

younger parts of a kelp-lamina are close to
the rhizoid –>they are close to the sea floor and further away from the sea surface–>shaded by the
upper part of the lamina and by other individuals around
Younger parts are low light adapted and older parts are high light adapted
results may be a function of age as well as spatially across and along the lamina

Question 25

How did the different algae behave after exposure to high light ?

Answer 25

increasing ΦNPQ and ΦNO

Question 26

Why was it not possible to use the fluorescence kinetks mikroscope (FKM)?

Answer 26

dead cells or suboptimum conditions for in-vivo measurements
cover glass: mechanical stress
damage during sampling
Light and temperature stress during sampling and storage

Question 27

Can you determine between different algae using 77K? How?

Answer 27

PSI:PSII
emission spectra: search for typical peaks e.g. phycobiliproteins for red algae, fucoxanthin for brown algae, non of those for green algae

Question 28

How was it possible to see the beginning of grazing/decline of the bloom via 77K?

Answer 28

uncoupled chlorophyll was detected –> not bind to proteins anymore –> different emission