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Epidermal system

A deck of flashcards for Undergraduate Study of Biology.

QuestionAnswer
Main problem living on land Lack of water
Use of water in aquatic organisms Serves to support them, is available to all parts which provides the nutrients in available form and dissolved gases.
How may a plant evolve into living on land? They must be able to obtain water from the soil which is in a short supply. This suggests adaptations in roots/root hairs and minimize losses. For transportation of water to the photosynthetic organs, plants need to evolve an internal transport system.
Plant cuticle adaption in land In order to minimize losses, an impermeable cuticle developed quite early in the history of land plants. Due to its prevention in gas exchange, they developed stomata that could open and close.
Stomata are found in sporophytes or gametophytes? They are found in sporophytes, and not gametophytes.
Are hydromes/hydroids true xylems? They aren't true xylem, they don't have lignin in the walls. They are water-conducting cells.
Cooksonia Cooksonia is an extinct grouping of primitive land plants. Earliest differentially-thickened conducting cells.
Tracheophyta Vascular plants, also known as tracheophytes and also higher plants, form a large group of plants that are defined as those land plants that have lignified tissues for conducting water and minerals throughout the plant.
Stele The central core of the stem and root of a vascular plant, consisting of the vascular tissue (xylem and phloem) and associated supporting tissue.
Protostele The most primitive form of stele, consisting of a solid core of xylem encased by phloem or of xylem interspersed with phloem. The roots of all vascular plants, as well as the stems of lycophytes, have protosteles.
Evolution of stele All results in an increased contact area between the xylem & phloem of the stele and the ground tissue
Solenostele A type of siphonostele, in which the vascular tissue in the stem forms a central cylinder around a pith, with widely spaced leaf gaps.
Dictyostele A stele in which the vascular cylinder is broken up into a longitudinal series or network of vascular strands around a central pith (as in many ferns)
Difference between Solenostele and Dictyostele The number of leaf gaps in a transverse section
Siphonostele A stele consisting of vascular tissue surrounding a central core of pith parenchyma.
Rhyniophytes A class of extinct early vascular plants. They have naked axes which branch dichotomously. All axes have terminal sporangia. Sporangia have longitudinal dehiscene. The stele was a protostele with centrarch or endarch protoxylem.
Protoxylem The first part of the primary xylem that matures (Raven et al 1999) and these cells are usually smaller than the metaxylem.
Zosterophylls Similar to rhyniophytes, naked axes branching dichotomously. However, sporangia lateral on the axes groups (cones). Sporangia round or kidney shaped. Dehiscene transverse rather than longitudinal.
Lycophytes Have lateral sporangia, borne in groups (cones/storbili). Sporangia transverse dehiscence. Stems exarch protoxylem with a type of leaf called microphyll.
Dehiscence The splitting at maturity along a built-in line of weakness in a plant structure in order to release its contents, and is common among anthers and sporangia. Sometimes this involves the complete detachment of a part.
Microphylls Single vascular strand and no side veins.
Selaginella Second living genus of Lycophyta. Also known as Spike mosses. It goes through the heterosporous life cycle with 2 spores: Megaspores & Microspores.
Created by: theecloud