Biology unit 1

• The plant kingdom, also known as Plantae, is divided into five kingdoms: Monera, Protista, Fungi, Animalia, and Plantae.
• Fungi, and members of the Monera and Protista having cell walls have been excluded from Plantae.
• Cyanobacteria, also referred to as blue green algae, are not 'algae' anymore.
• Algae, Bryophytes, Pteridophytes, Gymnosperms, and Angiosperms are included under Plantae.
• Earliest systems of classification used only gross superficial morphological characters such as habit, colour, number and shape of leaves, etc.
• These systems were artificial and separated closely related species since they were based on a few characteristics.
• Chlamydomonas is a type of algae.
• Sphagnum is a type of moss.
• Liverworts and moss are different types of plants.
• Syngamy and triple fusion are different types of fertilization methods.
• Moss is a type of plant.
• Monocots and dicots are different types of angiosperms.
• Algae is a type of plant.
• Cycas is a type of pteridophyte.
• Red algae and brown algae are different types of algae.
• Gymnosperm is a type of gymnosperm.
• Homosporous and heterosporous pteridophyte are different types of plants.
• Selaginella is a type of algae.
• Natural classification systems developed, which were based on natural affinities among the organisms and considered both external and internal features, like ultra-structure, anatomy, embryology and phytochemistry.
• A classification for flowering plants was given by George Bentham and Joseph Dalton Hooker.
• Phylogenetic classification systems based on evolutionary relationships between the various organisms are acceptable.
• Numerical Taxonomy, which is now easily carried out using computers, is based on all observable characteristics.
• Cytotaxonomy, based on cytological information like chromosome number, structure, behaviour, and chemotaxonomy, based on the chemical constituents of the plant, are also used by taxonomists these days.
• Algae are chlorophyll-bearing, simple, thalloid, autotrophic and largely aquatic (both fresh water and marine) organisms.
• Algae occur in a variety of other habitats: moist stones, soils and wood.
• Some of the marine forms such as kelps, form massive plant bodies.
• Meiosis in the zygote results in the formation of haploid spores.
• The spores germinate to form gametophytes which require cool, damp places to grow.
• This kind of life cycle is termed as diplontic.
• In addition, all seed bearing plants i.e., gymnosperms and angiosperms, follow this pattern with some variations, wherein, the gametophytic phase is few to multi-celled.
• The gametophytic phase is represented by the single to few-celled haploid gametophyte.
• The main plant body of a bryophyte is gamete-producing and is called a gametophyte.
• Bryophytes and pteridophytes, interestingly, exhibit an intermediate condition (Haplo-diplontic) ; both phases are multicellular.
• The spores germinate to form gametophytes.
• These organs possess well-differentiated vascular tissues.
• Water is required for transfer of male gametes to archegonium where zygote is formed after fertilisation.
• There are no free-living sporophytes.
• The sporophytes bear sporangia which produce spores.
• The zygote produces a sporophyte.
• The sporophyte produces haploid spores.