Plant Reproduction and Evolution

Plant Reproduction and Evolution

• Seedless plants have both male and female gametophytes in the same plant
• Seeds provide nutrients for the developing embryo, enabling plant reproduction
• Rhizoma are modified stems that store nutrients for the plant, often containing significant amounts of oil
• Stramenophiles have hairy flagella
• Dinoflagellates are major photosynthetic organisms, producing oxygen
• Angiosperms have flowers as their reproductive organs
• Conjugation involves direct DNA transfer between bacteria through a pilus
• Transformation is the uptake of free DNA by bacteria from the environment
• Transduction is the transfer of DNA mediated by a bacteriophage (virus)

Plant Structures and Functions

• Flowers are the reproductive organs of seed plants
• Seeds protect the embryo and provide nutrients for early growth and development
• Fruits enclose seeds and assist in seed dispersal
• Plant chloroplasts originated from cyanobacteria via endosymbiosis, being the only prokaryotes that generate oxygen, important in carbon and nitrogen cycles
• Chemical recycling occurs between living and nonliving components through decomposers and photosynthetic organisms involved in carbon and nitrogen fixation
• Euglena (Excavata) exhibits photosynthetic attributes
• All land plants are embryophytes
• Phylum Radiolaria are associated with crude oil formation

Bryophytes (Non-vascular Plants)

• Bryophytes (liverworts, mosses, hornworts) are the earliest diverging lineages of land plants
• Mosses thrive in moist environments and can survive extreme conditions, often found in forests and wetlands
• Rhizoids anchor gametophytes to substrates
• Sperm from antheridia require water for movement to eggs in archegonia
• Diploid sporophytes grow from archegonia and depend on gametophytes for nourishment

Vascular Plants

• Vascular sporophytes exhibit independence from gametophytes
• Vascular plants possess features like lignified vascular tissue, well-developed roots, and leaves, as well as sporophylls
• Seedless vascular plants (lycophytes and monilophytes) lack seeds
• Lycophytes include both small herbaceous and ancient large tree forms
• Seedless vascular plants contributed to global cooling during the Carboniferous period, with decayed remnants forming coal
• Water is not needed for fertilization in seed plants

Gymnosperms

• Gymnosperms are a group of seed plants with a dominance of the sporophyte generation
• They include cycads, ginkgoes, gnetophytes, and conifers
• Gymnosperms appear early in the plant fossil record and were prominent in Mesozoic terrestrial environments
• Seeds develop from fertilized ovules, and pollen facilitates sperm transfer to ovules

Angiosperms

• Angiosperms (flowering plants) are divided into magnoliids, monocots, and eudicots
• Flowers consist of modified leaves—sepals, petals, stamens (pollen), and carpels (ovules)
• Ovaries ripen into fruits, facilitating seed dispersal by wind, water, or animals
• Angiosperms originated during the Cretaceous period and now dominate terrestrial ecosystems
• Angiosperms and animal interactions (like pollination) have contributed significantly to their success

Human Dependence on Plants

• Humans rely on seed plants for various purposes, such as food, wood, and medicinal products