PLANT DIVERSITY I

YOU MUST KNOW…• WHY LAND PLANTS ARE THOUGHT TO

HAVE EVOLVED FROM GREEN ALGAE• SOME OF THE DISADVANTAGES AND

ADVANTAGES OF LIFE ON LAND• THAT PLANTS HAVE A UNIQUE LIFE

CYCLE TERMED ALTERNATION OF GENERATIONS WITH A GAMETOPHYTE GENERATION AND A SPOROPHYTE GENERATION

YOU MUST KNOW…• THE ROLE OF ANTHERIDIA AND

ARCHEGONIA IN GAMETOPHYTES• THE MAJOR CHARACTERISTICS

OF BRYOPHYTES• THE MAJOR CHARACTERISTICS

OF SEEDLESS VASCULAR PLANTS

CONCEPT 29.1• LAND PLANTS EVOLVED FROM

GREEN ALGAE

• CHAROPHYTES – PLANTS EVOLVED FROM GREEN ALGAE – EVIDENCE IS:

• PRODUCE CELLULOSE FOR CELL WALLS IN THE SAME FASHION

• THE PEROXISOMES HAVE ENZYMES THAT REDUCE THE LOSS OF ORGANIC PRODUCTS IN PHOTORESPIRATION

• SPERM STRUCTURE IS CLOSELY RELATED• BOTH PRODUCE CELL PLATES IN THE

SAME WAY DURING CELL DIVISION• RELATED ANALYSIS OF NUCLEAR AND

CHLOROPLAST GENES

MOVEMENT ON LAND• ADVANTAGE – INCREASED SUNLIGHT,

MORE CARBON DIOXIDE IN THE ATMOSPHERE, SOILS RICH IN NUTRIENTS, FEWER PREDATORS

• CHALLENGE – LACK OF WATER, DESICCATION, LACK OF STRUCTURAL SUPPORT AGAINST GRAVITY

LAND PLANT’S LIFE CYCLE• ALTERNATION OF GENERATION (2

MULTICELLULAR STAGES)• GAMETOPHYTE STAGE – PLANT CELLS

ARE HAPLOID (GAMETES ARE PRODUCED)

• SPOROPHYTE STAGE – PLANT CELLS ARE DIPLOID (ZYGOTE) THAT DIVIDE MITOTICALLY

• SPOROPHYTE PRODUCES SPORES BY MEIOSIS

• ZYGOTE DEVELOPS IN FEMALE PARENT

• GAMETANGIA – ORGANS THAT PRODUCES GAMETES

• ARCHEGONIA – FEMALE GAMETANGIA – PRODUCES ONE EGG

• ANTHERIDIA – MALE GAMETANGIA – PRODUCES MANY SPERM

CONCEPT 29.2• MOSSES AND OTHER

NONVASCULAR PLANTS HAVE THEIR LIFE CYCLES DOMINATED BY GAMETOPHYTES

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BRYOPHYTES• 3 PHYLA – MOSSES, LIVERWORTS,

AND HORNWORTS• NONVASCULAR (NO XYLEM OR

PHLOEM TISSUE)• GAMETOPHYTES ARE THE DOMINANT

STAGE OF THE LIFE CYCLE• ARCHEGONIA AND ANTHERIDIA ARE

FOUND ON THE GAMETOPHYTES• REQUIRE WATER FOR THE SPERM TO

SWIM TO THE EGG DURING FERTILIZATION

BRYOPHYTES• ALTHOUGH

PHOTOSYNTHETIC WHEN YOUNG, MUST ABSORB WATER, SUGARS, AND OTHER NUTRIENTS FROM PARENTAL GAMETOPHYTES

CONCEPT 29.3• FERNS AND OTHER SEEDLESS

VASCULAR PLANTS WERE THE FIRST PLANTS TO GROW TALL

• PLANTS GREW TALLER BECAUSE OF VASCULAR TISSUES, GAINING ACCESS TO LIGHT

• SEEDLESS VASCULAR PLANT LIFE CYCLE IS DOMINATED BY THE SPOROPHYTE STAGE

• MEIOSIS OCCURS IN STRUCTURES CALLED SPORANGIA, PRODUCING HAPLOID SPORES

• CONTINUE TO REQUIRE WATER FOR THE SPERM TO REACH THE EGG