Biology 120 Lab Cerritos College

BIOLOGY 120 LAB CERRITOS COLLEGE

Manual Exercise 6 L. L. Harris

ALGAE – BRYOPHYTES – PTEROPHYTES

(rev. 7.22.03)

I. INTRODUCTION

A. Groupings

Today begins our survey of the Kingdom Plantae. In the interest of time, our survey will consist of the major divisions (phyla) of this kingdom only. We can artificially separate the major phyla two ways:

1) Non-Vascular Plants versus Vascular Plants

2) Seedless Plants versus Seed Plants

An argument for an third artificial separation can also be made – one can divide the kingdom into the so-called Lower Plants and Higher Plants. This third means of separation takes into account both of the classifications mentioned earlier. A so-called lower plant will be described as a multicellular, phototrophic organism that displays:

1) little or no tissue differentiation

2) no true vascular tissue (no xylem, no phloem)

3) reproductive structures that are simple one-celled/few-celled structures

4) development of the zygote outside the female reproductive organ

B. The Transition Onto Land

All life is believed to have had its beginnings in the seas; given time (a long time!) terrestrial existence

would eventually be achieved. Today’s lab will begin with water-living phototrophs and end with plants that were the first to make the true transition onto land. The following list cites several problems that needed to be solved before a true land existence (independent of "standing water") was realized:

1) How to obtain water when the fluid not longer bathes the entire surface of the plant body

2) Transport of water and dissolved substances from restricted areas of intake to other parts of the plant body – and transport the products of photosynthesis to those parts of the plant that do not carry out this process themselves.

3) Prevent excessive loss of water by evaporation.

4) Keep a moist surface for gas exchanges when the surrounding medium is air; no longer water

5) Means to support the plant body against the pull of gravity when the buoyancy of an aqueous

medium is no longer available.

6) Carry out reproduction when there is little or no water for a flagellated sperm cell

7) Prevent the desiccation of the zygote and early embryonic plant.

8) How to withstand the extreme fluctuations in temperature, humidity, wind, light, and other

environmental parameters to which terrestrial organisms are often subjected.

II. PHOTOTROPHS OF THE SEAS (and other bodies of water!)

A. THE DIATOMS (These have long been members of the Kingdom Protista)

Premier Phototroph of the Planet – some might say! 75% of the Earth is covered with water. This is where living diatoms are found. Fossil diatom deposits are found deposited where waters (seas, lakes) once covered the Earth. Commercial uses are due the silIca contained in their cell walls.

Observe Displays, make wet-mounts of living diatoms or look at prepared slides, know some of the commercial uses of Diatoms:

__________________________________________________________

B. THE ALGAL DIVISIONS (Algae are currently members of the Kingdom Protista)

1. GREEN ALGAE (Division Chlorophyta) – Some are unicellular, most are multicellular. Believed to

have given rise to the first "Land Plants". Found in Marine & Fresh Waters.

Examples: _____________________________________________________________________

2. RED ALGAE (Division Rhodophyta) – Mostly marine; few are freshwater species. Not all are Red!

Some are black, violet, brownish, yellow, or even green!

Examples: _____________________________________________________________________

3. BROWN ALGAE (Division Phaeophyta) – Almost exclusively marine; the freshwater species being quite rare. These are the algae most of us think of as the "seaweeds". They are the "sea kelps".

Found along rocky coasts of the cooler parts of the oceans. Some are warm water species.

Examples: _____________________________________________________________________

Commercial Value of Algae: (I will not have you attribute these to their algal division)

Agar _________________________________________________________________________

Carrageenan ___________________________________________________________________

_______________________________________________________________________

Others: _______________________________________________________________________

General Anatomy of a Sea Kelp: Your Drawing:

Holdfast - __________________________________

Stipe - ____________________________________

Bladder - __________________________________

Blade - ____________________________________

Frond – a collection of blades

III. THE PLANT KINGDOM

A. THE LIFE CYCLE OF PLANTS

AN ALTERNATION OF GENERATIONS: (Followed by all plants, not followed by all algae!)

SPOROPHYTE (2n) SPORES (1n) GAMETOPHYTE (1n)

M m

DIPLOID m m HAPLOID

GENERATION GENERATION

ZYGOTE (2n) GAMETES (1n)

KEY: 2n – diploid / 1n – haploid / M – meiosis / m - mitosis / F - fertilization

B. THE SEEDLESS PLANTS

1. MOSSES & LIVERWORTS (DIVISION BRYOPHYTA & DIVISION HEPATOPHYTA)

They lack true vascular tissue. So, in terms of general anatomy, they do not have true roots,

stems, or leaves.

Sketch of Moss:

They tend to be small and found in moist regions.

Why small? – _________________________________

Why moist regions?

Reason One: __________________________

Reason Two: __________________________

Gametophyte Generation is the dominant generation

for both Mosses and Liverworts: Sketch of Liverwort:

Asexual Reproduction – liverwort's Gemmae _________

Look at: living moss & liverwort plants (use dissecting scope)

2. FERNS (DIVISION PTEROPHYTA)

Sporophyte Generation is dominant.

"Advancement" over Mosses & Liverworts: Sporophyte has true vascular tissue (Xylem & Phloem)

(Gametophyte is avascular [must have open-water])

What "advantage" does vascular tissue offer? _________________________________________

General Anatomy of the Fern Sporophyte:

Your Drawing:

Rhizome - ___________________________________

Roots - _____________________________________

Frond - _____________________________________

Sori - _______________________________________

Sporangium - ________________________________

Ferns are "the Amphibians of the Plant Kingdom" – like Frogs,

Salamanders, and Toads the fern’s spores must land in water

if the avascular gametophyte is to be successful. (2 big reasons!)

Why? -_______________________________________________________________________

Look at: Living ferns (naked eye), Sori (use your Dissection scope), Wet mount of sori [use Compound

Light scope]; Prothallium slides (Demos at back of room)

More of Your Drawings:

IV. MORE VOCABULARY

SPOROPHYTE – _________________________________________________________________________

____________________________________________________________________________________

GAMETOPHYTE – ________________________________________________________________________

____________________________________________________________________________________

DOMINANT GENERATION – ________________________________________________________________

____________________________________________________________________________________

PHOTOTROPHS – ________________________________________________________________________

____________________________________________________________________________________

ASEXUAL REPRODUCTION – ______________________________________________________________

____________________________________________________________________________________

SEXUAL REPRODUCTION - ________________________________________________________________

____________________________________________________________________________________

DIOECIOUS – ___________________________________________________________________________

____________________________________________________________________________________

MONOECIOUS – _________________________________________________________________________

____________________________________________________________________________________

XYLEM – ________________________________________________________________________________

____________________________________________________________________________________

PHLOEM – _______________________________________________________________________________

____________________________________________________________________________________

SEED – _________________________________________________________________________________

____________________________________________________________________________________