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Unit 5: Photosynthesis

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V. Photosynthesis: CO2 + H2O O2 + glucose + H2O

A. The Properties of Light

1. light behaves as a wave2. the distance between the peaks of two consecutive waves

is measured in nanometers as the wavelength.

The Electromagnetic Spectrum

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3. Colors of Light & Their Properties

a. ROYGBIV: red, orange, yellow, green, blue, indigo, violet

b. Note that blue light and red light are on opposite sides

4. The Three Fates of Light

a. absorption: light energy retained by objects.This is the only type that may be used for photosynthesis

b. reflection: light energy not retained by objects so it

bounces back.

c. transmission: light energy not absorbed by the object, but

passes through it.

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d. Examples of the Three Fates of Light:

- if an object is white, all colors of light are reflected

- if an object is black, all colors are absorbed- if an object is red, only red is reflected. The others are

absorbed

Canis lupus Canis lupus Canis rufus

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B. Pigments

1. Pigments are molecules which absorb energy of specific

wavelengths.

2. Important Plant Pigments and TLCa. chlorophyll a

- the green and most important pigment of

photosynthesis

b. chlorophyll b

- green accessory pigment

c. carotene

- orange accessory pigment

3. Rate of Flowa. Rf= a/b

b. the more soluble the pigment, the further it

will travel on the TLC strip

c. give answer in decimal form

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C. Leaf Structure & Function For Photosynthesis

Cross Section of Leaf (p. 80)

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1. Structures in the Leaf

a. Water loss through evaporation is prevented by the cuticle.

The cuticle is waxy and non-cellular

b. The outermost layer of cells in the leaf are the upper andlowerepidermis

c. the palisade layer contains most of the chloroplasts of the

leaf where most of the photosynthesis takes place

d. the spongy layer contains more open space for air. The

open spaces allows gases to pass freely into leaf interior.

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2. Stomata

a. The stomata are the openings on the surface of the leafthrough which air passes

b. The stomata are surrounded by guard cells in the epidermal

layersc. when water moves into the guard cells through

osmosis, the guard cells swell so the stomata willopen.

d. when water moves out of the guard cells, the guard

cells shrivel so the stomata closes.

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Hypertonic Condition

(guard cells=flaccid)

Hypotonic Condition

(guard cells=turgid)

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Environmental Factors Affecting Stomata

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3. Why are Stomata Mostly on the Lower Epidermis?

a. The lower surface is more protected than the upper surface,

thus concentrating stomata on the lower surface will permitthe necessary gas exchange while minimizing risk to the plant

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