Life Cycles Moro Pigments

Question 1

What is the primary pigment involved in the photosynthetic systems of both Cyanobacteria and algae?

Answer 1

Chlorophyll a

Question 2

Where do the photosynthetic processes occur in eukaryotic organisms?

Answer 2

Inside the thylakoid membranes of chloroplasts.

Question 3

In cyanobacteria, where are the photosynthetic complexes embedded?

Answer 3

In thylakoids free in the cytoplasm

Question 4

What are the four multiprotein complexes responsible for the photosynthetic reaction in the thylakoid membrane?

Answer 4

• Photosystem II (PSII)
• Cyt b6f
• Photosystem I (PSI)
• ATP synthase

Question 5

Name two types of pigments involved in photosynthesis

Answer 5

Chlorophylls and Carotenoids

Question 6

Which chlorophyll types are usually found in some cyanobacteria?

Answer 6

Chlorophyll d and f.

Question 7

What role do carotenoids play in photosynthesis?

Answer 7

They contribute to light-harvesting (=their role in photosynthesis)

also:
- producing large amounts of secondary caroteins is a mechanism for protection against different stressors (moslty in green algae)
- photoprotection mechanisms in red algae rely on carotenoids (LUT-, ZEA-, CX-group)

Question 8

Which carotenoids are able to capture light in the green region of the spectrum (500-550 nm)?

Answer 8

Fucoxanthin, peridinin, and vaucheriaxanthin.

Question 9

What is the VAZ cycle in Pheophyceae?

Answer 9

The biosynthesis cycle of xanthophylls that changes depending on light conditions.

Question 10

What happens to the VAZ cycle when algae are exposed to high irradiances?

Answer 10

• biosynthesis of xanthophylls
• The cycle proceeds from violaxanthin to antheraxanthin to zeaxanthin

Question 11

What pigment is responsible for the brown coloration of the thallus in Pheophyceae?

Answer 11

Fucoxanthin.

Question 12

In which phyla are β,β-carotene and diatoxanthin most abundant?

Answer 12

Diatoms, Haptophytes, and Cryptophytes.

Question 13

What is a unique feature of Dunaliella species (green algae) in high irradiances?

Answer 13

• Increase in β-carotene
• as compared to a xantophill cycle

Question 14

What are the two types of secondary carotenoids synthesized by green algae?

Answer 14

• β,β-carotene and ketocarotenoids (e.g., Canthaxanthin)
• producing a large amount of secondary carotenoids is another mechanism for protection against different stressors

Question 15

Which accessory photosynthetic pigments are largely present in Cyanobacteria, Rhodophyta, and Cryptophyta?

Answer 15

Phycobiliproteins.

Question 16

Name the three main phycobiliproteins and their maximum absorption wavelengths.

Answer 16

• Phycoerythrin (570 nm)
• Phycocyanin (630 nm)
• Allophycocyanin (650 nm)

Question 17

How does seawater affect light absorption compared to air?

Answer 17

• Seawater absorbs light more strongly, with blue light penetrating the farthest depths
• infrared and ultraviolet e.g. stop in the first cm of depth

Question 18

What is the significance of accessory pigments in algae?

Answer 18

They allow algal growth at different depths by capturing light that chlorophyll cannot absorb.

Question 19

What pigments are used for identification in cyanobacteria?

Answer 19

Chlorophylls a, b, d; Carotenoids like β,β-carotene and zeaxanthin; and Phycobiliproteins like phycocyanin and phycoerythrin.

Question 20

Which chlorophyll allows cyanobacteria to utilize far-red light?

Answer 20

Chlorophyll d.

Question 21

What is the function of the orange carotenoid protein (OCP) in cyanobacteria?

Answer 21

It acts as a sensor of light intensity and helps in photoprotection by quenching excess energy.

Question 22

What is the major carotenoid in red algae species (Rhodophyta) that belong to the LUT group?

Answer 22

• photoprotective mechanisms rely on caroteinoids
• they play a key role in preventing damage
• the major carotenoid in red algae species (Rhodophyta) that belong to the LUT group is Lutein

Question 23

What pigments are present in dinoflagellates of the DINO-1 group?

Answer 23

Peridinin, β,β-carotene, diadinoxanthin, and others.

Question 24

Which group of dinoflagellates has a diatom endosymbiont?

Answer 24

DINO-3.

Question 25

What are the three main profiles of carotenoid composition in Rhodophyta?

Answer 25

LUT group (main carotenoid is lutein), ZEA group (main carotenoid is zeaxanthin), XC group (main carotenoid includes violaxanthin or antheraxanthin).

Question 26

What is the primary carotenoid in Porphyridium cruentum?

Answer 26

Zeaxanthin, belonging to the ZEA group.

Question 27

Which xanthophylls are found in the LUT group of red algae?

Answer 27

Lutein

Question 28

What makes dinoflagellates unique in terms of their pigment composition?

Answer 28

• They have likely incorporated various algal cells with different carotenoids into their bodies
• considering their pigments, they are the most differnet algal class

Question 29

What type of endosymbiont is present in DINO-3 group dinoflagellates?

Answer 29

Diatom endosymbiont.

Question 30

What pigment transformation occurs in the VAZ cycle under low irradiance?

Answer 30

Zeaxanthin to antheraxanthin to violaxanthin (ZAV cycle).

Question 31

How do diatoms protect themselves under high irradiance conditions?

Answer 31

By converting diadinoxanthin to diatoxanthin.

Question 32

What are secondary carotenoids, and when are they synthesized?

Answer 32

Carotenoids like β,β-carotene and ketocarotenoids (e.g., canthaxanthin) produced under environmental stress such as high irradiance or low nutrient availability.

Question 33

Which cyanobacteria pigment allows the capture of infrared light, extending photosynthesis further into the infrared region?

Answer 33

Chlorophyll f

Question 34

in responses to changes in light quantity and quality, cyanobacteria have evolved various regulation strategies, to adjust the functions of the PSI and PSII complexes.
These strategies include:

Answer 34

PBS stands for Phycobilisomes

Question 35

What is non-photochemical quenching in cyanobacteria?

Answer 35

A mechanism to protect photosystems from excessive light using the orange carotenoid protein (OCP).

Question 36

How do cyanobacteria use light quality to regulate the synthesis of phycobiliproteins?

Answer 36

By increasing phycocyanin synthesis under red light and phycoerythrin synthesis under green light.

Question 37

What are the major carotenoids found in Rhodophyta species belonging to the XC group?

Answer 37

Violaxanthin or antheraxanthin.