Pho.rs: Electrolysis, photosynthesis and spectrometry

A1 ^0.40

Balance the equations for the reactions occurring in the solution at the anode

$$\mathrm{H_2O} - e^- \to \mathrm{H^+ + O_2} \uparrow $$

and cathode:

$$\mathrm{Cu^{2+}} + e^- \to \mathrm{Cu^0}.$$

Assume that no other reactions occur at the anode and cathode.

Write down and balance the overall equation for the electrolysis of an aqueous solution of $\rm{CuSO_4}$.

$$\rm Cu SO_4 + H_2O \to$$

1 The equations at the cathode and anode are balanced: $$\mathrm{Cu^{2+}} + 2e^- \to \mathrm{Cu^0},$$$$ 2\mathrm{H_2O} - 4e^- \to 4\mathrm{H^+ + O_2} \uparrow.$$	2 × 0.10
2 The complete electrolysis equation is written down (possibly with incorrect coefficients): \[ \rm 2Cu SO_4 + 2H_2O \to 2H_2SO_4 + 2Cu + O_2 \uparrow. \]	0.10
3 The coefficients in the complete equation are correct.	0.10

A2 ^1.00

Prepare $V_0=150$ mL of copper sulfate with a molar concentration of $c_0=0.400~\mathrm{M}$. You are given copper sulfate powder ($\rm CuSO_4 \cdot 5 H_2 O$). How many grams $m_{bs}$ of powder are needed to prepare the specified solution? It can be assumed that the volume of the resultant copper sulfate solution is the same as the volume of the added water.

We will call the resulting solution “solution A2.” Pour $5$ mL of solution A2 into Answer tube A2.

1 The required amount of copper sulfate is expressed in terms of known quantities: $$\nu_{\rm bs} = c_0V_0.$$	0.20
2 The formula for $m_{bs}$ is obtained: $$m_{\rm bs} = c_0 V_0 \cdot M ({\rm CuSO_4 \cdot 5 H_2O}).$$	0.20
3 The correct numerical answer is obtained: $$m_{\rm bs}=15.0~{\rm g}.$$	0.20
4 The maximum absorption height differs by no more than 10% from the author's values.	0.40
5 The maximum absorption height differs by no more than 20% from the author's values.	0.20

A3 ^2.50

In accordance with instruction G2, perform electrolysis of $120$ mL of solution A2 for $t_0=1$ h at a current of $I=1$ A.

Record the dependence of the volume of oxygen released $V_{\rm O_2}$ on time $t$. Take at least 10 measurements. Plot the resulting dependence and draw an approximation curve.

1 The data points for the $V_{O_2}(t)$ dependence are obtained.	10 × 0.10
2 At least three points are measured in the range $t \in [0, 1200] ~ s$.	0.20
Plotting a graph
4 The difference between the maximum and minimum coordinates is at least 50% of the length of the corresponding axis	2 × 0.05
5 Each of the axes is signed.	2 × 0.05
6 Each of the axes is uniformly digitized.	2 × 0.05
7 The points are plotted according to the table values.	10 × 0.02
8 An approximation curve is plotted.	0.20
9 The graph has a characteristic shape (the rate of oxygen formation first increases and then reaches saturation).	0.60

A4 ^0.60

After electrolysis, stir the solution remaining in the electrolyzer. In accordance with the G2 instructions, filter approximately 20-25 mL of the stirred solution after electrolysis.

We will refer to the filtered solution as “solution A4.” Pour 5 ml of solution A4 into Answer tube A4.

1 The maximum absorption height differs from the authors' values by no more than 10%.	0.60
2 The maximum absorption height differs from the authors' values by no more than 20%.	0.40
3 The maximum absorption height differs from the authors' values by no more than 40%.	0.20

A5 ^0.20 Calculate the charge $Q$ that flowed during electrolysis based on the known value of the current.

1 Formula for determining charge: $$Q = It.$$	0.10
2 Numerical value: $$Q = 3600\text{ C}.$$	0.10

A6 ^0.30 The amount of oxygen released at task A3 can be used to determine the charge flow during electrolysis. Write a formula that relates the total volume of oxygen released $V_{\rm O_2}$ to the charge flow $Q_{\rm O_2}$. Calculate the numerical value of the charge $Q_{\rm O_2}$. Assume that the experiment takes place at a pressure of $p_0=10^5$ Pa and a temperature of $T_0=298$ K.

1 The formula for the number of oxygen molecules is written down: $$N_{O_2} = \frac{N_{A}p_0V_{O_2}}{RT_0}.$$	0.10
2 The relationship between the amount of oxygen and the charge that has passed is recorded: $$Q_{O_2} = 4e\cdot N_{O_2}.$$	0.10
3 The numerical answer is obtained: $$Q_{O_2} = [2580, 3160]\text{ C}.$$	0.10

B1 ^1.00 In the answer sheets, fill in the table showing what volume of solution A2 ($V_\textbf{A2}$) and water ($V_{\rm H_2O}$) need to be mixed to obtain $4$ mL of the required solutions.

Note that the initial solution A2 has very strong absorption, so in this task you calculate its dilution by a factor of 10 or more.

1 Correct values of the $V_\textbf{A2}$ volumes are obtained.	5 × 0.10
2 Correct values of the $V_{\rm H_2O}$ volumes are obtained.	5 × 0.10

B2 ^1.50

Using the calculations made in the previous task, prepare five solutions in optical cuvettes. In accordance with instruction G1, measure the absorption spectrum of each of the five solutions.

Save the measured spectra in the “Results/B2” folder on your desktop under the names “B2.{cuvette number}.txt” (for example, “B2.3.txt”).

1 The spectra are saved and the peak values differ from those of the authors by no more than 20%.

5 × 0.30

B3 ^0.40 Specify the wavelength $\lambda_0$ of light that is most strongly absorbed by $\rm CuSO_4$ solutions.

1 $$\lambda_0 \in \left[ 820, 830\right] \text{ nm}$$	0.40
2 $$\lambda_0 \in \left[ 810, 840 \right] \text{ nm}$$	0.20

B4 ^2.00 For each cuvette, record the absorption spectra and the determine the absorption coefficients $A$ at the wavelength $\lambda_0$ that you have chosen. Plot a graph of the dependence of absorption $A$ on the molar concentration of copper ions $[\rm Cu^{2+}]$, draw a fitting straight line $A=s\cdot [\rm Cu^{2+}]$ and determine its slope $s$.

1 The peak absorption value $A(\lambda_0)$ is determined for each concentration.	5 × 0.10
Plotting a graph
3 The difference between the maximum and minimum coordinates is at least 50% of the length of the corresponding axis.	2 × 0.05
4 Each of the axes is signed.	2 × 0.05
5 Each of the axes is uniformly digitized.	2 × 0.05
6 The points are plotted according to the table values.	5 × 0.10
7 An approximating line is drawn.	0.20
8 $$s \in \left[ 23.7, 29.0 \right] \text{ a.u./M}$$	0.50
9 $$s \in \left[ 21.1, 31.7 \right] \text{ a.u./M}$$	0.20

B5 ^0.30 Measure the absorption spectrum of a 10-fold diluted solution of A4.

Save the measured spectrum in the “Results/B5” folder on your desktop under the name “B5.txt”.

1 The spectrum is saved and the peak value differs from the authors' by no more than 20%.

0.30

B6 ^0.80

Determine the concentration of copper ions $[\rm Cu^{2+}]_\textbf{A4}$ in solution A4.

1 The value $A(\lambda_0)$ is determined from the spectrum.	0.20
2 Formula $[{\rm Cu}^{2+}]_{\bf A4}=10 \cdot A(\lambda_0) / s$ is recorded or used.	0.20
3 $$[{\rm Cu}^{2+}]_{\bf A4}\in [0.225, 0.275]$$	0.40
4 $$[{\rm Cu}^{2+}]_{\bf A4}\in [0.200, 0.300]$$	0.20

B7 ^1.00 The decrease in copper ion concentration in the solution can also be used to determine the charge passed during electrolysis. Write a formula that relates the initial concentration of copper ions $c_0$, the final concentration of copper ions $[\rm Cu^{2+}]_\textbf{A4}$, and the charge flow $Q_{\rm Cu}$. Calculate the numerical value of the charge $Q_{\rm Cu}$. Assume the volume of the solution doesn't change throughout the electrolysis.

1 The formula of the amount of copper ions that reacted at the cathode is written: $$\nu = \left(c_0-\left[\text{Cu}^{2+}\right]_\bf{A4}\right)V_i.$$	0.30
2 The charge is expressed in terms of the amount of copper: $$Q_\text{Cu} = 2eN_A\nu$$	0.30
3 The numerical value is found: $$Q_{\rm Cu}\in[3920,4800]~\rm C$$	0.40

C1 ^1.50 At the end of the exercises, there is an enlarged graph (Fig. 11). Determine the absorption values $A_{peak}$ for each $\rm pH$ value on the graph. Determine the absorbance value $A_{iso}$ at the isosbestic point. Calculate the ratios $A_{peak}/A_{iso}$ for each $\rm pH$ value. For convenience, a table is provided on the answer sheet. Plot a graph of $A_{peak}/A_{iso} ({\rm pH})$ and draw an approximating curve.

1 The values $A_{peak}(\operatorname{pH})$ are obtained from the graph.	9 × 0.05
2 The value $A_{iso}$ is obtained from the graph.	0.06
3 The relative peak height is calculated (marked only when $A_{iso}$ and $A_{peak}$ are measured correctly)	9 × 0.03
Plotting a graph
5 The difference between the maximum and minimum coordinates is at least 50% of the length of the corresponding axis.	2 × 0.05
6 Each of the axes is signed.	2 × 0.05
7 Each of the axes is uniformly digitized.	2 × 0.05
8 The points are plotted according to the table values.	9 × 0.03
9 An approximating line is drawn.	0.15

C2 ^0.30

This step uses a thin glass cuvette with an adapter. Following the G1 instructions for thin cuvettes, obtain the absorption spectrum of undiluted solution A4 without indicator. Save the measured spectrum to the “Results/C2” folder on your desktop under the name “C2.txt”.

1 The spectrum is saved and the peak value differs from the authors' by no more than 20%.

0.30

С3 ^0.30

This step uses a thin glass cuvette with an adapter. Following the G1 instructions for thin cuvettes, obtain the absorption spectrum of the undiluted A4 solution with the indicator. Save the measured spectrum to the “Results/C3” folder on your desktop under the name “C3.txt”.

1 The spectrum is saved and the peak value differs from the authors' by no more than 20%.

0.30

C4 ^0.30 The introduction to the problem describes how absorption spectra are combined when there are several substances in solution. Based on measurements at tasks C2-C3, calculate the absorption $A'_{peak}$ at wavelength $\lambda^{CR}_{peak}$ caused only by the absorption of the indicator. What is the absorption $A'_{iso}$ at a wavelength of $\lambda^{CR}_{iso}=475$ nm caused only by the absorption of the indicator?

1 A recalculation formula is given, e.g. \[A'=A-A_0\]	0.10
2 The in answer is obtained: $$A'_{peak}\in[0.63,0.77]$$	0.10
3 The answer is obtained: \[A'_{iso}\in[0.22,0.26]\]	0.10

C5 ^0.50 Based on the data in task C4, calculate the ratio $A'_{peak}/A'_{iso}$. Using the graph from task C1, determine the value of ${\rm pH_{fin}}$ in solution A4.

1 The value is calculated: \[A'_{peak}/A'_{iso}\in[2.6,3.2]\]	0.20
2 The $\rm pH$ is determined: $$\text{pH}_\text{fin} \in [0.8,0.9]$$	0.30

C6 ^1.40 Fill in the remaining fields in the table on the answer sheets.

1 The table is completed.

14 × 0.10

С7 ^3.00

Perform the experiment described above, adding the specified amount $\Delta V$ of acid with concentration $C_{\rm HCl}$ at each step. Measure and save the absorption spectrum at each step according to instruction G1. Save the measured spectra in the folder on your desktop named “Results/C7” under the names “C7.{step number}.txt” (for example, “C7.2.txt”). You should end up with 8 spectra. Pour the remaining solution after obtaining all spectra into Answer tube C7.

1 The spectra are saved.	7 × 0.30
2 The solution in the test tube is correct (the $\rm pH$ differs by less than 0.05 from the authors').	0.90

C8 ^0.80 Display all spectra from item C7 in the program's working area. Determine the wavelength $\lambda^{BB}_{peak}$ at which absorption changes most significantly with $\rm pH$ changes. Determine the wavelength of the isosbestic point $\lambda^{BB}_{iso}$.

1 $$\lambda^{BB}_{peak} \in [580,600]~\rm nm$$	0.40
2 $$\lambda^{BB}_{iso} \in [490,510]~нм$$	0.40

C9 ^1.50 Plot the graph of the dependence of the absorption ratio at wavelengths $\lambda^{BB}_{peak}$ and $\lambda^{BB}_{iso}$ on $\rm pH$ (i.e., the graph $A_{peak}/A_{iso} ({\rm pH})$ for bromophenol blue).

1 The points for the graph are calculated.	8 × 0.10
Plotting a graph
3 The difference between the maximum and minimum coordinates is at least 50% of the length of the corresponding axis.	2 × 0.05
4 Each of the axes is signed.	2 × 0.05
5 Each of the axes is uniformly digitized.	2 × 0.05
6 The points are plotted according to the table values.	8 × 0.02
7 A smoothing curve is drawn.	0.24

С10 ^0.30

This step uses a thin glass cuvette with an adapter. Following the G1 instructions for thin cuvettes, obtain the absorption spectrum of the undiluted A2 solution without indicator. Save the measured spectrum to the “Results/C10” folder on your desktop under the name “C10.txt”.

1 The spectrum is saved and the peak value differs from the authors' by no more than 20%.

0.30

С11 ^0.30

This step uses a thin glass cuvette with an adapter. Following the G1 instructions for thin cuvettes, obtain the absorption spectrum of the undiluted A2 solution with indicator. Save the measured spectrum to the “Results/C11” folder on your desktop under the name “C11.txt”.

1 The spectrum is saved and the peak value differs from the authors' by no more than 20%.

0.30

С12 ^0.30

Based on the measurements in questions C10-C11, calculate the absorption $A'_{peak}$ at wavelength $\lambda^{BB}_{peak}$ caused only by the absorption of the indicator. What is the absorption $A'_{iso}$ at a wavelength of $\lambda^{BB}_{iso}$ nm caused only by the absorption of the indicator?

1 \[A'_{peak}\in[0.9,1.0]\]	0.15
2 \[A'_{iso}\in[0.33,0.39]\]	0.15

С13 ^0.50 Based on the data in task C12, calculate the ratio $A'_{peak}/A'_{iso}$. Using the graph from task C9, determine the value of ${\rm pH_{ini}}$ in solution A2.

1 The value is calculated: \[A'_{peak}/A'_{iso}\in[2.3,2.7]\]	0.25
2 $$\text{pH}_\text{ini}\in[3.82,4.02]$$	0.25

С14 ^1.00 By increasing the concentration of hydrogen ions in the solution (i.e., decreasing the $\rm pH$), it is also possible to determine the charge passed during electrolysis. Write a formula that relates the initial ${\rm pH_{ini}}$ of the solution, the final ${\rm pH_{fin}}$ of the solution, and the charge $Q_{\rm pH}$ that has passed through. Calculate the numerical value of the charge $Q_{\rm pH}$.

1 The formula is obtained: $$Q_\text{pH} = eN_AV_i(10^{-\text{pH}_\text{fin}}-10^{-\text{pH}_\text{ini}})$$	0.50
2 The numerical answer is obtained: $$Q_\text{pH}\in[1480,1800]~\rm C$$	0.50

D1 ^0.70 Based on the laws you know, fill in the table on the answer sheet, checking only one of the options for each statement: true/false.

1 The number of correct answers.

7 × 0.10

D2 ^0.30 Select and mark with a check mark on the answer sheet the most reliable value of the leaked charge.

1 The correct answer is chosen.

0.30

E1 ^0.60

For each LED battery, measure the voltage across the 3 LEDs connected in series and calculate the voltage across single LED when the power source is turned on. Fill in the table in the answer sheets.

1 $$U_r=[1.75, 2.13]~\rm V$$	0.20
2 $$U_g=[2.51, 3.07]~\rm V$$	0.20
3 $$U_b=[2.6, 3.18]~ \rm V$$	0.20

E2 ^0.30 Find the current $I$ flowing through the LEDs of each color. Fill in the table in the answer sheets.

1 $$I_r=[0.15, 0.19]~\rm A$$	0.10
2 $$I_g=[0.33, 0.41]~\rm A$$	0.10
3 $$I_b=[0.24, 0.30]~\rm A$$	0.10

E3 ^0.30 Find the power of light $P$ emitted by each of the LED. Fill in the table in the answer sheets.

1 $$P_r=[38, 46]~\rm mW$$	0.10
2 $$P_g=[46, 56]~\rm mW$$	0.10
3 $$P_b=[103, 127]~\rm mW$$	0.10

E4 ^1.00

For this task, use microorganism $A$. Prepare the setup for measurements according to the G3 instructions. Turn on the light source and start timing.

If no oxygen release is observed 30 minutes after the start of the experiment, record zero values for $V_{O_2}$ in the table in the answer sheets.

If oxygen release is observed 30 minutes after the start of the experiment, continue the experiment for another 1.5 hours. Record the volume of oxygen $V_{O_2}$ released when illuminated by different colors of light in the table on the answer sheet.

1 $$V_{\rm red} = [100, 350] \ \text{mm}^3$$	0.20
2 $$V_{\rm green} = [50, 200] \ \text{mm}^3$$	0.20
3 $$V_{\rm blue} = [100, 350] \ \text{mm}^3$$	0.20
4 The amount of oxygen released by the red and blue LEDs is greater than that of the green LED.	0.40

E5 ^1.00 For microorganism $B$, repeat the procedure described in the previous question.
Fill in the table in the answer sheets.

1 $$V_{\rm red} = [0, 18] \ \text{mm}^3$$	0.20
2 $$V_{\rm green} = [0, 18] \ \text{mm}^3$$	0.20
3 $$V_{\rm blue} = [0, 18] \ \text{mm}^3$$	0.20
4 It is stated that oxygen is not released for all three colors of LED.	0.40

E6 ^1.00 According to instruction G4 get the image of the cells in Goryaev's chamber for both microorganisms $A$ and $B$. Save the acquired images to the “Results/E6” folder on your desktop under the name “E6.A.jpg” and “E6.B.jpg” respectively.

According to instruction G4, use Goryaev's chamber to count the number of cells in the four small squares $n_A$ and $n_B$ of microorganisms $A$ and $B$.

The edge of the large square of the Goryaev chamber is 0.2 mm, the depth of the chamber is 0.1 mm, and the large square consists of 16 small squares. Count the total number of cells $N_A$ and $N_B$ of microorganisms $A$ and $B$ inside a 20 ml syringe. Write down the calculation formula showing how $n_A$ and $N_A$ are related.

1 $$n_A = [30, 70]$$	0.20
2 $$n_B = [40, 500]$$	0.20
3 The formula is obtained: $$N = n \cdot 20 \text{mL} \cdot \dfrac{16}{0.2 \times 0.2 \times 0.1 \text{mm}^3 \cdot 4}.$$	0.20
4 $$N_A/n_A = 2 \cdot 10^7$$The point is only evaluated if $n_A$ hits the confidence interval.	0.20
5 $$N_B/n_B = 2 \cdot 10^7$$The point is only evaluated if $n_B$ hits the confidence interval.	0.20

E7 ^1.20 Using the data obtained in tasks E4, E5, and E6, calculate the photosynthetic efficiency $E$ for both microorganisms and all colors of light. Fill in the table in the answer sheets.

1

Photosynthesis efficiency $E, \ 10^{-15}~\dfrac{\text{m}^3}{\text{cell}\cdot \text{W}}$

Microorganism	Red	Green	Blue
$А$	[1.5,15]	[0.6,8.0]	[0.6,6.0]
$В$	[0,0.6]	[0,0.5]	[0,0.2]

2 Correct answers for microorganism $A$.

3 × 0.30

3 Correct answers for microorganism $B$.

3 × 0.10

E8 ^1.00

Using the data obtained in questions E3 and E7, fill in the table in the answer sheets.

1

The number of correct answers.

	True	False	It cannot be concluded from the experiment
Organism $A$ is unable to perform photosynthesis when illuminated by green light.		v
Organism $B$ is capable of moving toward more optimal conditions for photosynthesis.	v
Organisms $A$ and $B$ perform the same type of photosynthesis.		v
Organism $B$ performs photosynthesis more efficiently when illuminated with red light.			v
Organism $B$ performs anoxygenic photosynthesis.	v

5 × 0.20

F1 ^2.00

According to instruction G5, perform thin-layer chromatography of extracts of microorganisms $A$ and $B$.

Immediately after completing the chromatography and drying the plate, analyze the table and carefully mark the spots corresponding to chlorophylls with an “X” and the spots corresponding to carotenoids with an “O” on the plate with a pencil.

Raise the HELP sign so that an assistant can come to you and photograph the plate.

Place the marked plate in Answer tube F1.

1 In the chromatogram of the microorganism $A$ extract, carotenoids and chlorophylls are separated.	0.40
2 In the chromatogram of the microorganism $B$ extract, carotenoids and chlorophylls are separated.	0.40
3 All the chlorophyll spots for microorganism $A$ are marked correctly.	0.30
4 All the chlorophyll spots for microorganism $B$ are marked correctly.	0.30
5 All carotenoid spots for microorganism $A$ are marked correctly.	0.30
6 All carotenoid spots for microorganism $B$ are marked correctly.	0.30

F2 ^1.00

In accordance with instruction G1, obtain the absorption spectrum of extracts from microorganisms $A$ and $B$.

Save the measured spectra in the folder on the desktop “Results/F2” under the names “F2.A.txt” and “F2.B.txt” for microorganisms $A$ and $B$, respectively.

Pour 3 mL of the microorganism extract solutions you measured into Answer tube F2.A and Answer tube F2.B.

1 The spectra are saved.	2 × 0.30
2 The spectrum is saved and the peak value differs from the authors' by no more than 25%.	2 × 0.20

F3 ^1.40 Based on the chromatograms you have obtained, as well as the absorption spectra, mark whether the statements are true or false on the answer sheet.

1

The number of correct answers.

	True	False
Chlorophylls will have two maxima in the red and blue regions of the absorption spectrum.	v
Carotenoids can be found on the chromatogram of organism $B$.	v
Carotenoids are more polar than chlorophylls.		v
In this experiment, carotenoids can only be clearly identified by their mobility, as their absorption spectra are similar.	v
On the chromatogram of organism $A$ extract, chlorophylls have the highest mobility.		v
Bacteriochlorophyll absorbs the longer wavelength part of the spectrum than chlorophylls.	v
Carotenoids participate in electron transfer along the photosynthetic electron transport chain.		v

7 × 0.20

F4 ^0.80 What conclusions can be drawn from the results of thin-layer chromatography and absorption spectrum analysis? Mark whether the statements are true or false on the answer sheet.

1

The number of correct answers.

	True	False
Organism $B$ can use the longer wavelength part of the spectrum for photosynthesis.	v
The pigment compositions of organisms $A$ and $B$ are identical.		v
In mixed communities, organism $B$ is found in deeper layers than organism $A$.	v
The carotenoid sets of both organisms are identical.		v

4 × 0.20

H1 ^0.80

Select the correct statements about microorganisms.

1

The number of correct answers.

	True	False
Green algae are aerobic microorganisms.	v
Purple and green bacteria perform oxygenic photosynthesis.		v
Phototrophic bacteria can use reduced sulfur compounds as electron donors in anoxygenic photosynthesis.	v
Cyanobacteria mainly live in anaerobic conditions.		v

4 × 0.20

H2 ^0.80

The figure shows a diagram of a small pond with poor water circulation. Identify the zones of the pond (A-D) where the following microorganisms will live.

cyanobacteria and green algae
anaerobic decomposers of organic matter
green bacteria
purple bacteria

Write the numbers of the organisms in the table on the answer sheet.

1

The number of correct answers.

Pond zone	Microorganisms
A	1
B	4
C	3
D	2

4 × 0.20

H3 ^0.80 Based on the information about microorganisms $A$ and $B$ that you obtained during your research, determine in which pond zone (A-D from task H2) each of the microorganisms is most likely to live.

1

The number of correct answers.

Microorganism	Pond zone
Microorganism $A$	$A$
Microorganism $B$	$B$

2 × 0.40

H4 ^1.00 Cyanobacterial mat consists of many phototrophic and non-phototrophic microorganisms that are arranged in layers one below the other. Indicate whether the following statements are true or false.

1

The number of correct answers.

Microorganism	True	False
Microorganisms can move within the mat.	v
In the upper layer of the cyanobacterial mat, bright light increases the risk of photodamage to the photosynthetic apparatus of cells.	v
Non-phototrophic microorganisms can only exist deep within the cyanobacterial mat.		v
Phototrophic microorganisms with different sets of pigments can change places depending on changes in the wavelength range of sunlight.	v
At sunrise and sunset, bacteria capable of absorbing light in the shorter wavelength region of the spectrum will photosynthesize most actively.		v

5 × 0.20

Electrolysis, photosynthesis and spectrometry

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