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Posting Komentar. Pages Beranda. Minggu, 18 Januari contoh laporan praktikum biologi. Diversity of Plant and Animal Organisms. Basic theory.
Diversity of plant. Nonvascular plants lack vascular tissue and reproduce by producing spores. Thegametophyte generation is dominant. There are three divisions of nonvascularplants: Bryophyta, Hepaticophyta, and Anthocerophyta. Mosses and other nonvascularplants have life cycles dominatedby gametophytes. Bryophyte Gametophytes. Note that the terms Bryophyta and bryophyte are not synonymous. Bryophyta is the formal taxonomic name for the phylum that consists solely of mosses. As mentioned earlier, the term bryophyte is used informally to refer to all nonvascular plants—liverworts, mosses, and hornworts.
Nonvascular plants are not as common or as widespread in their distributionas vascular plants because life functions, including photosynthesisand reproduction, require a close association with water. Because a steadysupply of water is not available everywhere, nonvascular plants are limitedto moist habitats by streams and rivers or in temperate and tropical rainforests.
Recall that a lack of vascular tissue also limits the size of a plant. Indrier soils, there is not enough water to meet the needs of most nonvascularplants.
Their long-term survival in dry environments is limited by thisresource—water. Liverworts Phylum Hepatophyta. In medieval times, theirshape was thought to be a sign that the plants could help treat liver diseases. A typicalsporophyte can grow to about 5 cm high. Unlike a liverwort ormoss sporophyte, a hornwort sporophyte lacks a seta and consistsonly of a sporangium.
The sporangium releases mature spores bysplitting open, starting at the tip of the horn. The gametophytes,which are usually 1—2 cm in diameter, grow mostly horizontallyand often have multiple sporophytes attached. Mosses Phylum Bryophyta. Moss gametophytes, which range in height from less than 1 mm toup to 2 m, are less than 15 cm tall in most species. The familiarcarpet of moss you observe consists mainly of gametophytes.
Moss sporophytes are typically elongated and visible tothe naked eye, with heights ranging up to about 20 cm. Thoughgreen and photosynthetic when young, they turn tan or brownishred when ready to release spores. Bryophyte SporophytesAlthough bryophyte sporophytes are usually green and photosyntheticwhen young, they cannot live independently.
Theyremain attached to their parental gametophytes, from whichthey absorb sugars, amino acids, minerals, and water. Bryophytes have the smallest sporophytes of all extantplant groups, consistent with the hypothesis that largersporophytes evolved only later, in the vascular plants. A typicalbryophyte sporophyte consists of a foot, a seta, and a sporangium.
Embedded in the archegonium, the foot absorbsnutrients from the gametophyte. The seta plural, setae , orstalk, conducts these materials to the sporangium, also calleda capsule, which uses them to produce spores by meiosis.
One capsule can generate up to 50 million spores. In most mosses, the seta becomes elongated, enhancingspore dispersal by elevating the capsule. Typically, the upperpart of the capsule features a ring of interlocking, tooth-likestructures known as the peristome. This allows spores to be discharged gradually, via periodicgusts of wind that can carry them long distances.
They are represented by modern species. As in nonvascular plants, however, the sperm of ferns and all other seedless vascular plants are flagellated and swim through a film of water to reach eggs. In part because of these swimming sperm, seedless vascular plants today are most common in damp environments.
Unlike the nonvascular plants, these species had branched sporophytes that were not dependent on gametophytes for nutrition. Although these ancestors of vascular plants were only about 15 cm tall, their branching made possible more complex bodies with multiple sporangia.
As plant bodies became increasingly complex, competition for space and sunlight probably increased. This section describes the main traits that characterize living vascular plants: life cycles with dominant sporophytes, transport in vascular tissues called xylem and phloem, and well-developed roots and leaves, including spore-bearing leaves called sporophylls. Life Cycles with Dominant Sporophytes. Transport in Xylem and Phloem Vascular plants have two types of vascular tissue: xylem and phloem.
Xylem conducts most of the water and minerals. The xylem of most vascular plants includes tracheids, tubeshapedcells that carry water and minerals up from roots. Because nonvascular plants lack tracheids, vascular plantsare sometimes referred to as tracheophytes. The waterconducting cells in vascular plants are lignified; that is, their cell walls are strengthened by the polymer lignin.
The tissue called phloem has cells arranged into tubes that distribute sugars, amino acids, and other organic products. Lignified vascular tissue permitted vascular plants to grow tall. Their stems became strong enough to provide support against gravity, and they could transport water and mineral nutrients high above the ground. Instead of the rhizoids seen in bryophytes, roots evolved in the sporophytes of almost all vascular plants.
Roots are organs that absorb water and nutrients from the soil. Roots also anchor vascular plants, hence allowing the shoot system to grow taller. Evolution of Leaves Leaves increase the surface area of the plant body and serve asthe primary photosynthetic organ of vascular plants. In terms of size and complexity, leaves can be classified as either microphyllsor megaphylls. All of thelycophytes the oldest lineage of present-day vascular plants —and only the lycophyteshave microphylls, small, usually spine-shaped leaves supported by a single strand of vascular tissue.
Almost all other vascular plants have megaphylls, leaves with a highly branched vascular system; a few species have reduced leaves that appear to have evolved from megaphylls.
So named because they are typically larger than microphylls, megaphyllssupport greater photosynthetic productivity than microphyllsas a result of the greater surface area served by their network of veins. Megaphylls, by contrast, may have evolved from a series of branches lying close together on a stem. As one of these branches came to grow above, or overtop, the others, the lower branches became flattened and developed webbing that joined them to one another.
These joined branches thus became a leaf attached to the branch that overtopped them. Sporophylls and Spore Variations One milestone in the evolution of plants was the emergence of sporophylls, modified leaves that bear sporangia. Sporophyllsvary greatly in structure. For example, fern sporophylls produce clusters of sporangia known as sori singular, sorus , usually on the undersides of the sporophylls.
In many lycophytes and in most gymnosperms, groups of sporophyllsform cone-like structures called strobili singular, strobilus; from the Greek strobilos, cone. Most seedless vascular plant species are homosporous: They have one type of sporangium that produces one type of spore, which typically develops into a bisexual gametophyte,as in most ferns.
In contrast, a heterosporous species has two types of sporangia and produces two kinds of spores: Megasporangia on megasporophylls produce megaspores, which develop into female gametophytes; microsporangia on microsporophylls produce the comparatively smaller microspores, which develop into male gametophytes.
Lycophytes Phylum Lycophyta. Sporophytes have upright stems withmany small leaves, as well as groundhuggingstems that produce dichotomouslybranching roots.
Spike mosses are usuallyrelatively small and often grow horizontally. In many club mosses and spikemosses, sporophylls are clustered into clubshapedcones strobili. Quillworts, namedfor their leaf shape, form a single genuswhose members live in marshy areas or assubmerged aquatic plants.
Club mosses areall homosporous, whereas spike mossesand quillworts are all heterosporous. Pterophytes Phylum Pterophyta. The sporophytestypically have horizontal stems that giverise to large leaves called fronds, oftendivided into leaflets.
A frond grows as itscoiled tip, the fiddlehead, unfurls. Almost all species are homosporous. Thegametophyte in some species shrivels anddies after the young sporophyte detachesitself. In most species, sporophytes havestalked sporangia with springlike devicesthat catapult spores several meters. Some species have separate fertile conebearing and vegetative stems.
Horsetailsare homosporous, with cones releasingspores that typically give rise to bisexualgametophytes. Some vascular plants produce seeds in which reduced sporophyteplants are enclosed within a protective coat.
The seeds may be surroundedby a fruit or carried on the scales of a cone. Seed plants produce sporesIn seed plants, as in all other plants, spores are produced by the sporophytegeneration.
These spores develop into the male and female gametophytes. The male gametophyte develops inside a structure called apollen grain that includes sperm cells, nutrients, and a protective outercovering. The female gametophyte, which produces the egg cell, is containedwithin a sporophyte structure called an ovule.
The gymnosperm plantdivisions are:. Cycads have male and femalereproductive systems on separateplants, The male system includes cones thatproduce pollen grains, which producemotile sperm. Cycads are one of thefew seed plants that produce motilesperm. The female system includescones that produce ovules.
Thetrunks and leaves of many cycadsresemble those of palm trees, butcycads and palms are not closely relatedbecause palms are anthophytes. Today, this division is representedby only one living species, Ginkgobiloba.
K U U T E K R A A G O
Students learn the definition and some examples of taxonomic characters in invertebrate. Students learn morphological characters of several invertebrates. Taxonomic characters are unique attributes that are used to recognize a taxa that distinguishes it from other taxa. These attributes serve as a basis for grouping beings into certain taxa. Character can be in the form of color, shape, and structure of certain organs from a taxa Wahid,
Laporan Praktikum animal systematics