Chapter 3 outline from Quizlet.docx

Chapter 3 outline from Quizlet Characteristics and Diversity of Bryophytes General Characteristics of Bryophytes Bryophytes are small, flat plants thriving in moist environments. They can adapt to dry deserts, hot rocks, and even aquatic environments. Mosses exhibit resilience in extreme condit...

Chapter 3 outline from Quizlet Characteristics and Diversity of Bryophytes General Characteristics of Bryophytes Bryophytes are small, flat plants thriving in moist environments. They can adapt to dry deserts, hot rocks, and even aquatic environments. Mosses exhibit resilience in extreme conditions like the Arctic Circle and Antarctic continent. Some bryophytes, such as Fontinalis dalecarlica, can grow in low salinity aquatic environments. They significantly contribute to plant biodiversity and carbon storage. Contribution to Plant Evolution and Environmental Impact Earliest plants resembled bryophytes, aiding in understanding plant evolution. Bryophytes, like lichens, are pioneer colonizers of barren surfaces. Sensitive to air pollution, bryophytes are absent or reduced in polluted areas. Serve as models for early land plants, offering insights into environmental impact. Store large amounts of carbon, contributing to ecosystem balance. Comparative Structure and Reproduction Gametophyte Structure and Adaptations Bryophytes like liverworts and hornworts have flat, dichotomously branched gametophytes. Thalli facilitate water and CO2 uptake with specialized adaptations like pores. Leafy liverworts and mosses have structures resembling leaves and stems. Certain species show conducting functions in thalli, possibly precursor to vascular tissues. Cell Structure and Reproduction Mechanisms Bryophyte cells are interconnected by plasmodesmata, similar to vascular plants. Possess small disk-shaped plastids, with some species having a single large plastid per cell. Asexual reproduction occurs through fragmentation or gemmae production. Loss of zoospore production is linked to the absence of centrioles in spindles. Bryophytes vs. Vascular Plants and Charophytes Structural and Functional Contrasts Bryophytes lack water- and food-conducting tissues like xylem and phloem. Cell walls of bryophytes are non-lignified, distinguishing them from vascular plants. Sporophyte size and complexity differ between bryophytes and vascular plants. Bryophyte sporophytes are unbranched with one sporangium, unlike vascular plants. Shared characteristics with charophytes include male and female gametangia with a sterile jacket layer. Evolutionary Relationships and Reproductive Features Bryophytes and charophycean green algae share paraphyletic traits based on habitats and adaptations. Oogamous sexual reproduction is common, with zygotes retained within parental thallus. Apical meristem produces tissues in bryophytes and vascular plants. Bryophyte sporangia have sporopollenin walls for protection against decay and drying. Charophytes lack key characteristics present in bryophytes and vascular plants. Evolution of Plant Reproduction Sexual Reproduction in Bryophytes Antheridia and archegonia produce sperm and eggs respectively, often on separate gametophytes. Distinct sex chromosomes control sex determination during meiosis. Bryophytes were the first plants where sex chromosomes were identified. Antheridium consists of a protective layer surrounding spermatogenous cells. Spermatogenous cells develop into biflagellated sperm for fertilization. Zygote remains within archegonium for matrotrophy, providing nourishment. Plant Nutrient Transport and Placenta Apoplastic nutrient transport facilitated by placenta at the sporophyte-gametophyte interface. Bryophyte placenta includes transfer cells with increased surface area for nutrient exchange. Transfer cells found in vascular plants and Coleochaete suggest evolutionary link. Placental cells in Coleochaete indicate matrotrophy evolution in plant ancestors. Plant Evolution and Sporophyte Generation Multicellular, matrotrophic embryos are fundamental to all plant groups. Matrotrophy and plant placenta support diploid sporophyte production. Genetically diverse haploid spores provide an advantage to early plants. Sporophyte generation evolved from zygotes with delayed meiosis. Increased mitotic divisions enhance sporophyte size and spore production. Structural Adaptations in Bryophytes Epidermis and Stomata Stomata in mosses and hornworts regulate gas exchange and sporangium dehydration. Presence of stomata in bryophytes suggests an evolutionary link to vascular plants. Liverwort sporophytes lack stomata but have decay-resistant phenolic coverings. Hornwort sporophyte epidermis is protected by a cuticle layer. Bryophyte Spores and Germination Bryophyte spores enclosed in sporopollenin for survival during air dispersal. Spores germinate into protonemata, developing into gametophytes and gametangia. Protonemata are characteristic of mosses and some liverworts. Historical use of mosses for insulation in clothing. Comparative Structure & Reproduction Loss of zoospore production linked to absence of centrioles in spindles. Mitosis in liverworts suggests evolutionary stages towards centriole absence. Archegonia structure aids in sperm attraction and zygote nourishment. Nutrient transport facilitated by placenta and transfer cells in bryophytes. Bryophyte spores\' sporopollenin walls enable survival during dispersal. Protonemata development leads to gametophyte and gametangia formation. Diversity and Classification of Liverworts Phylum Marchantiophyta Overview Approximately 5200 liverwort species, often small and inconspicuous. Liverworts grow in various habitats, with the name \'liverwort\' reflecting their appearance. Gametophytes develop from spores or protonema-like filaments. Liverworts categorized into complex thalloid, leafy, and simple thalloid types. Complex Thalloid Liverworts Internal tissue differentiation in complex thalloid liverworts. Thick thallus with distinct upper chlorophyll-rich and lower colorless regions. Presence of rhizoids, scale rows, and air chambers in complex thalloid liverworts. Riccia and Ricciocarpus exhibit simple sporophyte structures. Sporophyte dispersal occurs upon decay of mature sporophyte. Conocephalum salebrosum Characteristics and growth habits of Conocephalum salebrosum liverwort. Specialized structures like gametophores bear sex organs in liverworts. Distinctive gametophores for antheridia and archegonia in Marchantia gametophytes. Sporophyte generation includes elongated elaters within mature sporangium. Reproductive Structures of Liverworts Antheridia and Archegonia Antheridia and archegonia are borne on specialized structures called antheridiophores and archegoniophores respectively. Sporophyte generation in liverworts includes a foot, short seta, and capsule. Mature sporangium contains elaters with hygroscopic wall thickenings that aid in spore dispersal. Elaters respond to humidity changes by twisting to disperse spores after capsule dehiscence. Leafy Liverworts Overview Comprising over 4000 of 5200 Marchantiophyta species, liverworts thrive in tropical and subtropical regions with high humidity. They grow on various plant surfaces like leaves and bark, forming small, well-branched mats. Abundant in temperate regions, some tropical species remain unidentified. Leafy liverworts have distinct leaf structures compared to mosses, with two rows of equal-sized leaves and a third row of smaller leaves. Comparison Between Liverworts and Mosses Leaf Structure Liverworts and mosses both have a single layer of undifferentiated cells. Moss leaves are usually equal in size and spirally arranged, while liverworts have two rows of equal-sized leaves and a third row of smaller leaves. Moss leaves splay outward in three dimensions, unlike liverwort leaves. Liverwort leaves can be highly lobed or dissected, whereas moss leaves are usually entire. Antheridia, Archegonium, and Perianth Antheridia are borne on androecium, which are modified leaves. Sporophyte and archegonium are surrounded by a tubular sheath called perianth. Perianth serves as a protective structure for the reproductive organs in liverworts. Moss Diversity and Characteristics Phylum Bryophyta Overview Various organisms are colloquially called mosses, but genuine mosses belong to the Bryophyta phylum. Bryophyta consists of classes like Sphagnidae, Andreaeidae, and Bryidae, with peat and granite mosses diverging early in moss evolution. Bryidae, the largest class, encompasses around 10,000 moss species. Class Sphagnidae - Peat Mosses Sphagnidae includes genera like Sphagnum and Ambuchanania, with Sphagnum having unique spore discharge mechanisms. Peat mosses contribute to soil acidity, have high water-holding capacity, and are used in horticulture and industrial applications. Efforts are ongoing to regenerate peatlands due to ecological concerns. Ecological Impact and Usage of Mosses Peatlands and Carbon Storage Sphagnum-dominated peatlands cover a significant portion of the Earth\'s surface and store large amounts of organic carbon. Peat, formed from mosses and other plants, is used as fuel and contributes to concerns about global warming. Peatlands play a crucial role in carbon sequestration and require conservation efforts. Class Bryidae - True Mosses Moss gametophytes in Bryidae range in size and have multicellular rhizoids and one cell-layer thick leaves. Some mosses have specialized water-conducting tissues like hydroids and food-conducting cells called leptoids. Bryidae includes most moss species, with leafy shoots developing from budlike structures on protonemata. Moss Structure and Reproduction Hydroids and Leptoids Hydroids are elongated cells facilitating water and solute transport. Leptoids surround hydroids in some moss genera, aiding in food conduction. Both cell types have living protoplasts with degenerate nuclei. Conducting cells in mosses resemble those of fossil plants called protracheophytes. Moss Sexual Cycle Involves production of male and female gametangia and specialized spore dispersal processes. Gametangia are produced by mature leafy gametophytes. Antheridia discharge sperm into water, sometimes carried by insects. Gametophytes can be unisexual or produce archegonia and antheridia. Moss Sporophytes Sporophytes are borne on gametophytes, providing nutrients. Foot at the base of the seta is embedded in gametophyte tissue. Simple sugars move across generations in moss Polytrichum. Sporangia take 6 to 18 months to mature in temperate species. Hornwort Structure and Reproduction Hornwort Gametophytes Rosetted gametophytes with dichotomous branching. Internal differentiation with Nostoc colonies supplying nitrogen. Mucilage-secreting cells for water retention. Some hornworts have associations with glomeromycetes. Hornwort Sporophytes Upright sporophyte structure with foot and cylindrical capsule. Sporophyte lacks a seta and forms a placenta for nourishment. Green sporophyte with photosynthetic cells and permanent stomata. Spore dispersal aided by pseudoelaters and twisting of sporangium wall. Bryophyte Classification and Characteristics Bryophyte Diversity Bryophytes consist of liverworts, mosses, and hornworts. Gametophytes are nutritionally independent, while sporophytes depend on them. Male and female sex organs have protective layers. Sporophytes differentiated into foot, seta, and capsule. Bryophyte Sporophyte Differences Liverworts lack stomata, while mosses and hornworts have them. Mosses have specialized conducting tissue resembling vascular plants. Hornworts lack specialized conducting tissue but have a unique basal meristem. Mosses classified into peat mosses, granite mosses, and \'true mosses.\' Ecological Importance and Evolution Bryophytes\' Ecological Role Abundant in temperate rainforests and tropical cloud forests. Moss Sphagnum plays a crucial role in the global carbon cycle. Bryophytes interact with various invertebrates, influencing ecosystems. Human activities may lead to the loss of bryophyte species and associated animals. Plant Evolution Plants likely evolved from charophycean green algae. Unique features include a phragmoplast and cell plate at cytokinesis. Bryophytes diverged earliest in plant evolution. Common plant characteristics include tissues from an apical meristem and heteromorphic generations.