Chapter 22 - Photosynthesis, Light, and Pigments

photosynthate

sugar product of photosynthesis

photosynthesis formula

CO₂ + H₂O + light → C₆H₁₂O₆ + O₂

what is the main photosynthetic organ in plants?

leaves

stomata

pores that let gases into the cell, the cell can also lose water through these pores

cuticle

the waxy protective layer

why is the leaf’s epidermis transparent?

to let light in for photosynthesis

electromagnetic (EM) radiation

energy that is given off by the sun

photon

“packet” of EM radiation energy

why is visible light the only light used in photosynthesis?

other light types can’t reach Earth and it has just the right amount of energy

when light hits an object, what can occur?

reflection, transmission, absorption

pigments

can absorb certain wavelengths and reflect others

chlorophylls (A + B)

the primary photosynthetic pigment in plants

where are chlorophylls located?

embedded in the thylakoid

accessory pigments

help in harvesting light

the main accessory pigments in plants

carotenoids (carotenes and xanthophylls) and cyanins

absorption spectrum

determined by how effectively wavelengths are absorbed

action spectrum

how well different wavelengths power photosynthesis

action and absorption spectrum relation

they are similar to each other

florescence

a lower energy photon releases light

resonance

when most energy is passed to a neighboring pigment

what is modern life dependent on?

the 5-10% of autotrophs performing photosynthesis

guard cells

regulate the size of the stomata

mesophyll

the layer inside of a leaf that is the main site of photosynthesis, is rich in chloroplasts

chloroplast

the organelle where photosynthesis occurs

vascular bundles (“veins”)

transport materials in and out of the leaf

xylem

tissues that water travels through

phloem

tissue that sap travels through

flavonoids

pigments that act as melanin for humans

what happens when light photons are absorbed?

energy is transferred to an electron and excites the electron