PLANT DIVERSITY 1BE SURE TO READ THE

DESCRIPTIONS OF ALTERNATION OF

GENERATIONS AND THE CHARACTERISTICS OF THE PLANT GROUPS IN

THE LAB MANUAL

The Next Two Weeks:overview of plant groups

• PLANT KINGDOM (major groups)– MOSSES (“non-vascular”)– FERNS– GYMNOSPERMS (conifers)– ANGIOSPERMS (flowering plants)

seedless

Vascular

WHY PLANTS MATTER• Base of food chain

– They are the ultimate/fundamental source of nutrients

– Make organic molecules available to other organisms (they fix carbon, make N-available)

• Make O2 available & remove CO2 from atmosphere

• Source of raw materials/resources– Wood (building materials)

– Paper

– Cloth/fabric

• Stabilize soil

• Cool and humidify environment

• Source of medicine, chemicals, etc…

• Aesthetics

Defining Characteristics of the Plant Kingdom:You know it’s a plant when…

• Multicellular

• Eukaryotic

• Photosynthetic Autotrophs– Chlorophyll

• Cell Walls of Cellulose

• Non-motile/mobile

• Alternation of Generations

ALTERNATION OF GENERATIONS:

see also diagram in lab manual

• Gametophyte: muticellular haploid—– HAPLOID = 1 COPY OF EACH CHROMOSOME– Produces unicellular haploid GAMETES (by mitosis)

that fertilize one another to make:

• Sporophyte: multicellular diploid—– DIPLOID = 2 COPIES OF EACH CHROMOSOME– Produces unicellular haploid SPORES (by meiosis)

that divide by mitosis to make the GAMETOPHYTES

HAPLOID: 1 copy of each chromosome

DIPLOID: 2 copy of each chromosome

If humans had alternation of generations

Background ConceptsReproduction:• ASEXUAL REPRODUCTION:

– Clones: offspring are genetically identical to one another and parent

– Fast, cheap, easy– Low risk to parent, and if environment is stable produces lots of

successful offspring quickly

• SEXUAL REPRODUCTION: – Genetically different/variable: offspring are different from

parent and one another– Slower, riskier, more expensive, for parent– but creates potential for offspring to have new and different

capabilities that could make them more successful or capable of dealing with a changing environment.

Background Concepts Cont.

Vascular Tissue:Specializes cells that transport materials around the plantCan transport “long distance”

– XYLEM: • transports materials absorbed from soil: water and minerals. • creates rigid support (so plant can grow big)

– PHLOEM: • transports sugars made by photosynthesis

Aquatic photosynthetic organism, that existed at some point in history, common ancestor to both algae and plants

Aquatic common ancestor of both plants and algae

Alg

ae

Pla

nts

In the aquatic env:• Obtaining water• Drying out• support• Sperm swimming to egg

Various levels of adaptation to dry land

PLANTS ARE TERRESTRIAL:Challenges of life on land…..

• Obtaining water– how do they get water to cells that need it?

• Drying out– how to prevent loss of water they have?– both the adult and juvanile plant

• Support (against gravity)– how do the plants support themselves as they grow upright (if

they do)

• Reproduction with swimming sperm in a terrestrial environment– How does the sperm get to the egg when it needs to swim– Also, sperm must not dry out as well

Adaptation

• Any characteristics that allows an organism to better survive and reproduce in its environment– Physical (morphological)– Physiological– Behavioral

HOW PLANTS WORK• Use Water (from ground), CO2, and sunlight energy to make food• WATER + CO2 SUGARS

– this is photosynthesis– This happens mostly in leaves (which also lose water)

MOSSES AND LIVERWORTS:

• No vascular tissue

• swimming sperm

• no true roots or leaves

MOSSES AND LIVERWORTS:

• What environment do they require?• Why are they limited to this environment?• How does sperm get to egg? Under what

conditions?• How do they obtain water?• Do they have vascular tissue? true roots? • Dominant Generation? • Why do they have to be smal

MOSSESL AND LIVERWORTS:

• WHY ARE THEY SMALL?– give two reasons

• WHY MUST THEY LIVE IN WET ENVIRONMENTS?– give two reasons

FERNS:• Have vascular tissue

• Have roots and true leaves

• have swimming sperm

• have spores

FERNS:• Do they have vascular tissue?• What are the leaves called?• What are their reproductive structures?• What are in sori• Roots?• Dominant Generation?• Do they grow tall?• Why can they grow this tall • How are they better adapted to dry land than

mosses/liverworts

FERNS:

• Why can they grow bigger then mosses?– give two reasons

• Why might you find ferns growing in places that are too dry for mosses?

• What kind of environments are they restricted to by reproduction?– what do they need for reproduction

Stomata• Openings in leaves that allow:

– gas exchange (primarily allows CO2 into plant)– water to exit plant– some water loss is necessary/needed, but too much is bad.

• The opening (stomata) are borded by two cells called guard cells.– Guard cells can open and close the stomata– If the stomata are closed what does that do to gas exchange?

Water loss?

• What surface of the leaf has most of the stomata? • Why does that make sense given that water is lost

through the stomata?

many stomata

Stomata w/ guard cells