Biology, Seedless Plants

Raven Biology 13th edition, CH 29

Life on Land, What were three major issues plants had to overcome to live on land?

Water loss, protection from sun's harmful effects, and effective dissemination of gametes.

Colonization of the Land, What role did fungi play in helping plants colonize land?

They helped make nutrients available to plants.

Green Algae and Land Plants, What are the two major clades of green algae and which is the sister clade to land plants?

Chlorophytes (never made it to land) and Charophytes (sister clade to land plants).

Green Algae and Land Plants, What is the term for charophytes and land plants together?

Streptophytes.

Green Algae and Land Plants, What are three trends seen in land plants regarding their life cycles?

They have multicellular haploid and diploid stages, show a trend toward more diploid embryo protection, and show a trend toward a reduced haploid stage.

Adaptations to terrestrial life, What two structures help protect plants from drying out?

Waxy cuticle and stomata.

Adaptations to terrestrial life, Why are bryophytes limited in size?

Because they lack vasculature.

Adaptations to terrestrial life, What two types of vascular tissue do tracheophytes have and what do they transport?

Xylem (conducts water) and phloem (transports sugars and nutrients).

Adaptations to terrestrial life, How did plants deal with UV-induced mutations?

By shifting to a dominant diploid generation, masking deleterious recessive mutations.

Haplodiplontic Life Cycle, What does the multicellular diploid sporophyte produce and how?

It produces haploid spores by meiosis from diploid spore mother cells (sporocytes) in sporangia.

Haplodiplontic Life Cycle, What does the multicellular haploid gametophyte produce and how?

It produces gametes by mitosis.

Haplodiplontic Life Cycle, What is the result of gamete fusion?

A diploid zygote, the first cell of the next sporophyte generation.

Haplodiplontic Land Plants, How do human and animal life cycles differ from those of all land plants?

Humans/animals have a diplontic life cycle (only diploid stage is multicellular); all land plants are haplodiplontic (both stages multicellular).

Haplodiplontic Land Plants, In mosses and angiosperms, which generation is large and which is small?

Moss: large gametophyte, small sporophyte. Angiosperm: small gametophyte, large sporophyte.

Bryophytes, What are bryophytes called due to their lack of specific cells?

Nontracheophytes (they lack tracheids).

Bryophytes, Why are mycorrhizal associations important for bryophytes?

They enhance water uptake through a symbiotic relationship with fungi.

Bryophyte Characteristics, How many species of bryophytes are there and what are the three clades?

~16,000 species in three clades: liverworts, mosses, and hornworts.

Bryophyte Characteristics, Which generation is dominant in bryophytes and what is it specialized for?

The gametophyte is dominant, small, and specialized for photosynthesis.

Bryophyte Characteristics, Why do bryophytes require water for sexual reproduction?

Because sperm must swim to the egg.

Liverworts, What percentage of liverworts are leafy and resemble mosses?

80%.

Liverworts, What shape are the gametangia of lobed liverworts and what other type of reproduction do they undergo?

Umbrella-shaped; they also undergo asexual reproduction.

Mosses, What do moss gametophytes consist of and why are they not true leaves?

Small, leaflike structures around a stemlike axis; they lack vascular tissue.

Mosses, What anchors mosses to the substrate and are they as efficient as roots?

Rhizoids; they are multicellular but not nearly as efficient at water absorption as roots.

Mosses, What are the names of the female and male gametangia and what is required for fertilization?

Archegonia (female) and antheridia (male); flagellated sperm require water to swim.

Hornworts, What is puzzling about hornwort origins and what does the photosynthetic sporophyte resemble?

They are likely among the earliest land plants but have no fossils until the Cretaceous; the sporophyte looks like a green horn.

Hornworts, Where is the sporophyte base embedded and what is unique about their cells?

gametophyte tissue, from which it derives nutrition; cells have a single large chloroplast.

Cooksonia, What was Cooksonia and when did it appear?

The first known vascular land plant, appeared about 420 MYA.

Cooksonia, What phylum did Cooksonia belong to and what did it lack?

Phylum Rhyniophyta; it lacked roots and leaves.

Vascular Tissue, What are the functions of xylem and phloem?

Xylem conducts water and minerals upward; phloem conducts sucrose and hormones throughout the plant.

Vascular Tissue, In which generation does vascular tissue develop and what other structures are found in vascular plant sporophytes?

Develops in the sporophyte; cuticle and stomata are also found.

Tracheophytes, What three clades of vascular plants are there?

Lycophytes (club mosses), Pterophytes (ferns etc.), and Seed plants.

Tracheophytes, What trend occurred in the evolution of tracheophytes regarding gametophyte size and gametangia?

Gametophyte reduced in size; reduction in multicellular gametangia as well.

Stems Evolved Early, How did the lack of roots limit the size of early vascular plants?

Roots anchor plants and provide extensive water uptake; without them, plants couldn't grow large or get enough water.

Roots, What is unique about true roots and in which group are they found?

They provide both transport and support; found only in tracheophytes.

Roots, How many times did roots likely evolve?

At least twice.

Leaves, What is the primary function of leaves and how many times did they evolve?

Increase surface area for photosynthesis; evolved twice.

Leaves, What are the two types of leaves and in which groups are they found?

Euphylls (true leaves) in ferns and seed plants; Lycophylls in lycophytes.

Seeds, What are three key features of seeds?

They are highly resistant, protect embryos, and contain a food supply.

Seeds, Which plant groups lack seeds and what advantage do fruits provide in angiosperms?

Lycophytes and pterophytes lack seeds; fruits add protection and aid in animal dispersal.

Lycophytes, What is the relationship of lycophytes to other vascular plants and what do they lack?

They are the sister group to all other vascular plants; they lack seeds.

Club Moss, Selaginella, How do club mosses resemble true mosses and how are they different?

Superficially resemble them, but have different vascular structure and reproductive processes.

Club Moss, Selaginella, What bears the spores and what is the relationship between gametophyte and sporophyte?

Specialized leaves bear spores; the sporophyte is dependent on the gametophyte until its leaves develop.

Pterophytes, What is required for fertilization in all pterophytes?

Water for flagellated sperm.

Whisk Ferns, What does the whisk fern sporophyte consist of?

Evenly forking green stems without true leaves or roots.

Whisk Ferns, What is unique about some whisk fern gametophytes?

Some develop elements of vascular tissue.

Horsetails, What is the single living genus of horsetails and what are their stems like?

Equisetum; stems are ribbed, jointed, and photosynthetic.

Horsetails, What emerges at each node and what are the cells rich in?

A whorl of nonphotosynthetic, scalelike leaves; cells have silica deposits.

Ferns, How many species of ferns are there and what did ancient forests of them form?

About 11,000 species; ancient forests formed coal 300 MYA.

Ferns, Which generations are photosynthetic in ferns?

Both the conspicuous sporophyte and the much smaller gametophyte.

Fern Life Cycle, How does the fern life cycle differ from that of a moss?

Fern sporophyte is more developed, independent, dominant, and has vascular tissue and differentiated organs.

Fern Life Cycle, What does the fern gametophyte lack?

Vascular tissue.

Fern morphology, What are fern leaves called and how do they develop?

Fronds; they develop as tightly rolled-up coils called "fiddleheads".

Fern reproduction, Where are sporangia found and what are the clusters called?

On the back of fronds in clusters called sori.

Fern reproduction, What do spore mother cells produce and how?

They produce haploid spores by meiosis.

Fern reproduction, What does the germinated spore grow into and how do sperm move?

Grows into a gametophyte; sperm are flagellated and require water