What are the two layers of the Marchantia thallus?
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An upper photosynthetic region and a lower storage region.
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What are the two layers of the Marchantia thallus?
An upper photosynthetic region and a lower storage region.
What are the two types of rhizoids found in Marchantia?
Smooth walled and tuberculate.
How are antherozoids attracted to the archegonium?
They are attracted chemotactically towards the neck of the archegonium.
What are the two types of appendages in the described structure?
What is the family name of the genus Marchantia?
Marchantiaceae.
What features can the margins of gemma cups have?
Hyaline, lobed, spiny, or entire.
What is a protonema?
A mass of green, branched, one-cell-thick filaments that grow into gametophytes.
What happens to spores under favorable conditions?
They absorb moisture and increase in size.
What is the family name that includes the genus Marchantia?
Marchantiaceae.
What class is Marchantia classified under?
Hepaticopsida or Marchantiopsida.
How do hornwort sporophytes differ from those of mosses?
Hornwort sporophytes resemble grass blades and have a cuticle, while moss sporophytes are larger and more complex.
How do the gametophytes of mosses and some liverworts differ from those of hornworts?
Mosses and some liverworts have more 'leafy' structures with stemlike features, while hornworts are flattened.
What are the two orders within the Marchantiidae subclass?
Marchantiales and Sphaerocarpales.
What is the structure of the diploid sporophyte in Bryophytes?
It consists of a basal foot, an elevating seta, and a terminal sporangium (capsule).
What is the function of the appendages?
Protection of the growing point and retention of water by capillary action.
What structures are used for asexual reproduction in Marchantia?
Gemma cups.
What leads to the scattering of spores in the air?
Jerky movement of elaters due to their hygroscopic nature.
What role do bryophytes play in rainfall interception?
They are effective rainfall interceptors, helping to prevent soil erosion.
How do sperm reach the ovum in Bryophytes?
Sperm swim to the ovum by chemotaxis in a water film.
How does vegetative reproduction occur?
Through progressive death and decay, with new cells formed by the apical cell.
What causes the valves of the sporophyte capsule to roll back?
Annular thickening in jacket cells.
What structure do spores form after repeated divisions?
A 6-8 celled filamentous structure with a rhizoid at one end.
What are adventitious branches?
Branches that some species possess on the ventral surface, which can grow into new thalli when separated.
What is located at the tip of the neck in archegonia?
A rosette of 4 cover cells.
What arises from the floor of the gemma cup?
Many small, stalked, discoid, and biconvex gemmae.
What role do mucilage hairs play in gemmae?
They imbibe water and help in the dispersal of gemmae.
What is the structure of an antheridiophore?
It has a 1-3 cm long stalk that bears an 8-lobed peltate disc.
What type of sporophytes do liverworts have compared to other bryophytes?
Liverworts have the simplest sporophytes among bryophytes.
What happens to moss sporophytes as they prepare to release spores?
They turn tan or brownish red.
What is unique about Bryophyte sporophytes compared to other plants?
They have the smallest and simplest sporophytes of all modern plants.
What does the apical cell of the filamentous structure give rise to?
It cuts off derivatives on lateral sides and finally gives rise to the gametophyte.
What type of plants are Marchantia?
Simple plants without roots or vascular systems.
What are the neck cells in the neck of archegonia?
6 vertical rows of cells that enclose 4-8 neck canal cells.
What feature do the sporophytes of hornworts and mosses share with vascular plants?
They have epidermal stomata.
Why are Bryophyte sporophytes dependent on gametophytes?
They depend on gametophytes for sugars, amino acids, minerals, and water.
What structures do male and female thalli bear in Marchantia?
Male thallus bears antheridiophores and female thallus bears archegoniophores.
What does the venter of an archegonium contain?
A large egg cell and a relatively small venter canal cell.
What division does Marchantia belong to?
Bryophyta.
What color are the scales on the ventral surface of Marchantia?
Violet, due to anthocyanin pigments.
Why are bryophytes limited to moist habitats and small size?
Due to the absence of vascular tissue.
What happens to gemmae when they come in contact with the ground?
They start germinating immediately.
What are the two subclasses of the class Hepaticopsida or Marchantiopsida?
Marchantiidae and Jungermanniidae.
Describe the structure of air pores.
Barrel-shaped with 4-8 superimposed tiers of cells; each tier consists of a ring of 4-5 cells.
What is the role of gemmae in reproduction?
Gemmae are involved in asexual reproduction, allowing for the formation of new plants.
What are gemma cups?
Cupules present on the dorsal surface along the midrib region.
What occurs after antherozoids enter the archegonium?
Only one antherozoid fuses with the egg, leading to the formation of a zygote.
What are rhizoids?
Tubular cells or filaments of cells that anchor bryophytes.
What is the function of the ostiole in antheridia?
It is a pore through which water enters the antheridial chamber.
What characterizes the storage region in the structure?
A compact zone of several layers of polygonal parenchymatous cells, devoid of chloroplasts and intercellular spaces.
What is the structure of the dorsal surface of Marchantia?
It has a shallow groove with a distinct midrib, polygonal areas, air pores, and gemma cups.
What happens to the venter canal and neck canal cells during fertilization?
They degenerate to form a mucilaginous substance that imbibes water.
What types of cells does a gemma contain?
Chloroplast-containing cells and rhizoidal cells.
What is the significance of bryophytes in ecosystems?
They prevent soil erosion, provide food for animals, and contribute to nutrient cycles.
What is the structure of an archegonium?
A stalked flask-shaped structure with a basal swollen venter and an elongated neck.
How do the cells in the lowermost tier of air pores appear?
They project inward, giving the pore a star-shaped appearance.
What type of reproduction do antheridia and archegonia in Marchantia represent?
Sexual reproduction.
Why is water essential in the fertilization process?
It facilitates the movement of antherozoids to the archegonium.
What is the structure of a gemma?
Constricted in the middle with two notches possessing a row of apical cells.
How long are spores viable?
About a year.
What happens during the dehiscence of an antheridium?
Water causes some cells to disintegrate, rupturing the antheridium and releasing antherozoids.
What is the photosynthetic region's location and structure?
Lies below the upper epidermis, consisting of large air chambers separated by single-layered partition walls.
What is the growth habitat of Marchantia polymorpha?
Cool, moist, and shady places.
How does the sporophyte capsule dehisce?
The single-layered capsule wall splits into longitudinal valves extending from apex to middle.
What type of plant is Marchantia?
A heterothallic or dioecious plant.
What is the structure of an archegoniophore?
It has a slightly longer stalk and a terminal disc that is 8-lobed.
What structures do protonema produce when resources are available?
Meristems that generate gamete-producing structures called gametophores.
What commercial use does peat moss (Sphagnum) have?
It is used as fuel, soil conditioner, and by florists.
What are the two forms of plant body in Bryophytes?
Thalloid attached by rhizoids or differentiated into stem-like and leaf-like structures.
What is the function of archegonia in Bryophytes?
It is the female sex organ that produces a single egg.
What are the three classes of Bryophytes?
Hepaticopsida (liverworts), Anthocerotopsida (hornworts), and Musci (mosses).
Who coined the term Bryophyta and when?
Braun in 1864.
What is the dominant stage in the life cycle of Bryophytes?
The gametophyte stage, which is haploid.
What are Bryophytes?
Non-vascular plants that have no seeds, no roots, and no vascular tissue.
How many species of Bryophytes are there?
About 35,000 species.
What type of ancestors did Bryophytes evolve from?
Green algal ancestors, closely related to Charophytes.
