Photosynthetic Live in aqueous environments (ie. In or near

water) Lack external tubes to move water and

materials from one part of the plant to another

Unicellular or multicellular Cells have a cell wall Contain chlorophyll a (sometimes other forms

of chlorophyll also) Complicated alternating sexual & asexual

reproduction cycles

Unicellular algae = Kingdom Protista

Multicellular algae = Kingdom Plantae

Pros don’t need protection from drying out

can have very thin leaf-like structures these thin structures can exchange O2, CO2, &

nutrients directly with the H2O no specialized tissues for carrying

2. don’t need stem-like structures for support

3. reproductive cells can swim through water

Cons water absorbs much of the suns energy

that chlorophyll needs as it passes through it

particularly, sea water absorbs large amounts of red and violet wavelengths

1881, the German plant physiologist T. W. Engelmann placed a filamentous green alga under the microscope and illuminated it with a tiny spectrum of visible light.

In the medium surrounding the strands were motile, aerobic bacteria.

After a few minutes, the bacteria had congregated around the portions of the filament illuminated by red and blue light.

Assuming that the bacteria were congregating in regions where oxygen was being evolved in photosynthesis, Engelmann concluded that red and blue light are the most effective colors for photosynthesis.

With modern instruments, a plot of the rate of photosynthesis as a function of wavelength of light produces a graph like this. More precise than Engelmann's but telling the same story.

because sea water absorbs most of the red & violet wavelengths, the deeper you get, the dimmer and bluer the light gets

dim blue light contains very little energy that chlorophyll a can use

Algae has evolved two mechanisms to help Additional types of chlorophyll

Chlorophyll b Chlorophyll c Chlorophyll d

Accessory pigments Absorb different wavelength of light than

chlorophyll and pass the energy they absorb on for photosynthesis

Reflect different wavelengths of light than chlorophyll wide range of algae color

1. Write a paragraph explaining how the following adaptations contribute to the survival of algae in water and might not contribute to the survival of algae on dry land

Thin leaf like structures No waterproof covering No stem like structures No system of internal tubes

2. Write a paragraph explaining the restriction that aquatic life places on algae’s photosynthetic ability, the proof of this theory, and the adaptations it has resulted in

CLASSIFIED ACCORDING TO TYPES OF CHLOROPHYL & ACCESORY PIGMENTS THEY HAVE

Colonies: Assemblage of individual cells with variable or constant number of cells that remain constant throughout the colony life

Coenobium: Colony with constant number of cells, which cannot survive alone; specific „tasks“ among groups of cells is common

•Single Celled – Chlamydomonas

•Colonial – Volvox

•Multicellular – Ulva

CONTAIN CHOROPHYLLS a & b STORE FOOD AS STARCH

CONTAIN CHLOROPHYLLS a & c ALSO CONTAIN FUCOXANTHIN

ACCESORY PIGMENT

CONTAIN CHOROPHYLL a & sometimes d

ALSO HAVE PHYCOBILIN ACCESORY PIGMENTS

LIVE DEEPER IN THE OCEANS BECAUSE PHYCOBILIN IS VERY EFFICIENT AT ABSORBING BLUE LIGHT

Algae, the major food of fish (and thus indirectly of many other animals), are a keystone in the aquatic food chain of life; they are the primary producers of the food that provides the energy to power the whole system.

They are also important to aquatic life in their capacity to supply oxygen through photosynthesis.

Seaweeds, e.g., the kelps and the red algae (nori), have long been used as a source of food, especially in Asia.

Kelp are also much used as fertilizer, and kelp ash is used industrially for its potassium and sodium salts.

agar and carrageen, used as a stabilizer in foods, cosmetics, and paints.