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Studijní materiály
Zjednodušená ukázka:
Stáhnout celý tento materiálPLANT KINGDOM
A. Plant tissue
-basic unit of every plant – plant cell
-in unicellular plants, the single cell has the function of whole organism
-in lower multicellular plants, the body structure is rather simple and the cell from which the plant is created are very similar in both structure and function
-in higher multicellular plants, the plant body is divided into root, stem and leaf (in flowering plants also flower and fruit present) – cells of each of the parts of plant body differ in function, shape and size; the set of cells with the same function and similar size and shape forms a tissue
-according to thickness, presence of intercellular spaces and shape, we differ:
-parenchyma – thin cell walls, intercellular spaces present
-prosenchyma – young cells with thin walls, older with thick walls; no intercellular spaces; the cells are elongated
-collenchyma – two types: corner collenchyma (thin cells which are fatten in corners) and plate collenchyma (thin cells with one side of the cell fatten)
-sclerenchyma – thich walls with channels through which plasmodesms (plasmatic threads) go (they attach another cells); mechanical support
Meristematic tissue
-created by small parenchymatic cells with quite big nuclei
-these cells are still dividing → enable the growth
-two types exist:
-primary (apical) meristem – at apical growing points (in stem and root)
-secondary (lateral) meristem – when meristematic cells are not in apical growing point, they may loose its function, stop to divide and become permanent tissue
-cambium (creates secondary xylem and phloem)
-felogen (cork-creating tissue)
-calus
Permanent tissue
-created from differentiated cells with proper function which do not divide
-we differ 4 types:
-epidermal tissue – the body of higher plants is covered by epidermis (tile-like cells which are close to each other and do not contain chlorophyll), the cell walls are thickened at the outer sides and covered by cuticle (from cutin – lipid-like substance which is impermeable of water and gases), for gas and water exchange there are special organs – stomata (created from two guard cells; in dicotyledons on lower side of leaf, in monocotyledons on both sides, on water plants on upper side) – when the air moisture is high, stomata are open, when the sir moisture is low, the stomata are closed; part of epidermal tissues are also trichomes
-covering trichomes – protective function, both unicellular and multicellular, with needle point, can be branched
-glandular trichomes – with boll on the end; excrete aqueous solutions of inorganic substances and sugars, slime, essential oils and oleoresin
-stinging trichomes – bottle-like shape, unicellular, not branched, at the top the cell wall is replaced by fragile silicon dioxide – when touched, the top of trichome breaks and stinging, often toxic substance is released causing itching
-vascular tissue – main function is transport of various substances inside the plant; as strands of elongated cells they go through root and stem to leaves where it divides into veins; two types exist and they form vascular bundles
-xylem – formed by tracheids and treachea
-tracheids – elongated cells with thich lignified cell wall
-vessel element (tracheje) – building blocks of vessels, enable ascending transport – water and minerals transported from roots to leaves, they have also strengthening function
-phloem – consists of living elongated cells with no nuclei - sieve-tube cells; transport assimilates from leaves to other parts of plant body
-according to position of xylem and phloem we differ vascular bundles:
-collateral – phloem at outer side of stem, xylem on inner side
-bicollateral – xylem is surrounded by phloem on both sides, outer phloem thicker than inner
-radial – phloem and xylem next to each other, they alternate regularly, surrounded by sheath → form one unit
-concentric – xylem surrounded by phloem (hadrocentric) or phloem surrounded by xylem (leptocentric)
-strengthening tissue – consists of bundles of tough fibers; its main function is to support and strengthen the plant
-basic tissue – parenchymatic cells, fill the space between epidermal and vascular tissue; various functions
-photosynthetic tissue – contain a lot of chlorophyll
-storage tissue – contain a lot of leucoplasts and starch grains
-water tissue – storage of water
-earenchymatic tissue – storage of water
-excretive tissue – secrete latex, essential oils, oleoresin, alkaloids
B. Plant organs
Root
-it firstly appears during germination, grows gravitrophically, attaches the plant in soil and absorbs water and minerals = taproot (various shapes)
-lateral roots – grow from taproot, branch again
-adventitious roots – grow from stem (there is many of them)
-apical growing point of root is created from meristematic tissue and is protected by root cap (parenchymatic)
-on the surface of root there is rhizodermis (one layer of cells), below is multi-layered cortex (parenchyma) – its deepest layer is very thick and creates endodermis, below there is pericycle (parenchyma, those cells can be divided → create lateral roots), below is vascular tissue and just in the middle there is medulla
-root hair – elongated epidermal cells, increase the area for absorbtion
-metamorphosis of roots
-kořenové hlízy – storage
-bulvy
-přísavky – in parasitic or semi-parasitic plants, attack the host cell
-vzdušné kořeny – absorb the air moisture and oxygen
-příčepivé kořeny – attachment of plant to background
Stem
-shoot elongation of root
-at the top, there is apical growing point (also in stipules – places of lead attachment) in form of bud
-not all the cells grow the same → internodes (places where the cells elongate a lot) and nodes (places where the cells grow just a little, where the leaves are created)
-on the surface there is epidermis, below is cortex (parenchyma), its deepest layer is called starch sheath (contain a lot of starch grains) and divides cortex from medulla with vascular bundles
-in dicotyledons, the vascular bundles are arranged in circle, in modotyledons they are freely spread
-herbs have smooth, juicy stem = lodyha; there are several types of lodyha:
-stvol – stem without leaves, ends with flower or inflorescence
-stéblo – hollow segmented stem
-timber species have lignified stems; they are divided to shrubs, semi-shrubs and trees; for those plants its typical that their stem grows abroad = secondary growth – caused by:
-cambium – secondary meristematic tissue, by its action new xylem grows towards inside of the stem and new phloem towards outside of the stem; cambium divides from spring to august – firstly the cells are big and have thin cells (řídké dřevo), lately the cells are small and have thick walls (letní dřevo); the layers created during one year are called tree-rings (according to them we can state the age of tree)
-phellogen – secondary meristematic tissue, its main function is to produce cork (tough protective material – it protects the inside of plant when the bark breaks because of secondary growth – impermeable for water and gases → lenticels – small holes enabling the gas exchange)
-branching of stem
-vidličnaté (evolutionary older, less frequent) or postranní
-nopodial (the lateral branches are not higher than the main stem) or sympodial (the lateral branches are higher than the main stem)
-metamorphosis of stem
-storage of water – cactuses
-photosynthetic function – in plants in which the leaves shrinked
-brachyblasts in larches
-storage organs – stonkové hlízy – crocus
-rhizomes – underground stem (the plant survives winter)
-storage organs – oddenkové hlízy – potatoes
-reproductive organs – šlahouny –strawberries
-úponky – attachment of plant – vine
Structure of leaf
Outer structure of leaf
-usually flat organ of shoot
-can be divided into lamina and petiole (sometimes without petiole → přisedlý)
Inner structure of leaf
-the main functions: synthesis of organic compounds, transpiration, gas exchange
-side functions: storage (onion), can be modified to thorns (berberis), bines (peas), trap organs in carnivorous plants, they can be covered by sticky trichomes or modified to flowers enabling reproduction
*Anatomy of C3 leaf (ex. pissum sativum)
-plants of temperate zones
-chloroplasts in palisade mesophyll
-cells of vascular bundles do not contain chloroplasts
-intensity of photosynthesis decreases when percentage of carbon dioxide in air is below 0,033% (when is the concentration below 0,005%, the photosynthesis stops); percentage of oxygen in air is higher than 21%; temperature is higher than 30°C (stomata are closed)
*Anatomy of C4 leaf (ex. corn)
-plants of tropical zones
-palisade mesophyll is arranged annularly around the vascular bundles which contain chloroplasts
-the intensity of photosynthesis is affected neither by concentrations of carbon dioxide and oxygen in air nor by temperature
C. Reproductive organs of angiosperms
-flower is a set of modified leaves which are adapted for reproduction
-it has two main parts – stamen (male reproductive organ) and carpel (female reproductive organ) – those organs are protected against the bad conditions by sepals (green “leaves”) and petals (colorful “leaves”) – all these organs grow from receptacle
-when sepals and petals have the same color → perigone
-stamen consists of filament and anther (consists of two pollen sacs where the male gametes – pollen grains – are created)
-carpel consists of ovary (place of creation of female gametes), style and stigma
-according to position of ovary with respect to receptacle, we differ:
-hypogynous plants
-perigynous plants
-epigynous plants
-monoecious plants – plants which have in their flowers both male and female reproductive organs
-dioecious plants – plants which have in their flowers only male or only female reproductive organs
-the plants do not usually have only one flower on their stem; inflorescence is more often
-simple inflorescence
-hroznovitá inflorescence – main stem higher than lateral stems
-vrcholičnatá inflorescence – lateral stems
Vloženo: 8.07.2011
Velikost: 1,32 MB
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