BioInteractive Photosynthetic Pigments and Light Absorption

Question 1

Which wavelengths of light does chlorophyll a absorb most strongly?

Accepted Answer

Blue (~430 nm) and red (~662 nm)

Answer

Chlorophyll a has strong absorption peaks in the blue and red portions of the visible spectrum.

Question 2

What is the role of accessory pigments such as carotenoids in photosynthesis?

Accepted Answer

Absorb additional wavelengths of light and transfer energy to chlorophyll

Answer

Accessory pigments extend the range of light wavelengths captured and funnel that energy to the chlorophyll reaction centers.

Question 3

Why do leaves appear green to human eyes?

Accepted Answer

Chlorophyll reflects green wavelengths while absorbing red and blue

Answer

Chlorophyll absorbs red and blue light for photosynthesis but reflects green light, which is what we see.

Question 4

What is an action spectrum in the context of photosynthesis?

Accepted Answer

A graph showing the rate of photosynthesis at different wavelengths of light

Answer

An action spectrum plots the rate of photosynthesis against wavelengths of light, showing which wavelengths drive the most photosynthetic activity.

Question 5

Which pigment is responsible for the yellow and orange colors seen in autumn leaves?

Accepted Answer

Carotenoids

Answer

Carotenoids (carotenes and xanthophylls) produce yellow and orange colors that become visible when chlorophyll breaks down in autumn.

BioInteractive - Photosynthesis BioInteractive Test Practice Test