(11, 12) photosynthesis

pigments

nonpolar, and located in the thylakoid membranes of chloroplasts

used to absorb energy from the sun

• chlorophyll A, directly involved in converting light energy to chemical energy, releases O₂ as a byproduct

• chlorophyll B (accessory pigment), light harvesting pigment that transfers its energy to chlorophyll A

• carotenoids (accessory pigments) (carotenes and xanthophylls), acts as antioxidants to protect chlorophyll molecules from photooxidative damage

Rf value

the ration of how far the substance migrated up the chromatography paper compared to the distance migrated by the solvent

(distance of the top of the target band) / (distance of the highest band)

epidermis

• one cell layer thick

• secretes a waxy cuticle that retards the loss of water

• includes the upper epidermis and lower epidermis

stomata

located in the lower epidermis

gas exchange with the atmosphere can occur

guard cells

in each stoma

regulate the opening and closing of stoma

mesophyll

between the two layers of the epidermis

most photosynthesis occurs here

palisade mesophyll: consists of long cylindrical, relatively closed packed cells\

spongy mesophyll: contains spaces between cells for temporary storage of gases

veins

the medium in which water is supplied

contains special conducting tissue called xylem and phloem

xylem: conducts water from the roots to the leaf

phloem: distributes organic products of photosynthesis and other substances to areas of the plant where they are needed

cell fractionation

isolates and purifies cellular components by cellular disruption and differential centrifugation