BioInteractive Photosynthetic Pigments and Light Absorption 3

Question 1

What happens to a chlorophyll molecule after it absorbs a photon?

Accepted Answer

An electron is excited to a higher energy level

Answer

Photon absorption excites a chlorophyll electron to a higher energy state, from which it can be transferred to an electron acceptor.

Question 2

Which pigment is most directly involved in the initial photochemical reaction at the reaction center?

Accepted Answer

Chlorophyll a

Answer

Chlorophyll a is the primary pigment at the reaction centers (P680 and P700) where photochemistry actually occurs.

Question 3

What is photoprotection and which pigments are primarily responsible for it?

Accepted Answer

Protection of the photosynthetic machinery from excess light damage, primarily by carotenoids

Answer

Carotenoids quench excess excitation energy and scavenge reactive oxygen species, preventing photo-oxidative damage to the reaction centers.

Question 4

What color of light is LEAST effective at driving photosynthesis in most plants?

Accepted Answer

Green

Answer

Green light is mostly reflected by chlorophyll and therefore drives photosynthesis at the lowest rate compared to red and blue wavelengths.

Question 5

What is the significance of the 'red drop' observed in photosynthesis action spectra?

Accepted Answer

Photosynthetic efficiency drops sharply at wavelengths above 680 nm, suggesting two photosystems work together

Answer

The red drop showed that wavelengths above 680 nm alone are insufficient to drive photosynthesis efficiently, which helped reveal that two cooperating photosystems are required (the Emerson enhancement effect).

BioInteractive - Photosynthesis BioInteractive Test Practice Test

BioInteractive - Photosynthesis BioInteractive Test Practice Test

BioInteractive Photosynthetic Pigments and Light Absorption 3