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06 A növények teste

2014.04.09

 

Plants
Plants and their metabolism
Plants:
          Ancients: green algae
          Multicellular eukariotics
          Photosynthesis (use chlorophyll a, chlorophyll b, carotine and xanthophyll molecules)
          Cell wall is made of cellulose
          Energy store: starch
          Reproduction: sexual (haploidic and diploidic generation)
Importance of plants
·         Soil formation, protection (roots)
·         Producing of organic materials (food for heterotrophs) and oxygen
·         Fossil energy sources (crude oil, natural gas)
Autotroph metabolism
Photosynthesis
  1. Absorption of energy from sunlight using photosynthetic pigments andconversion of light energy to chemical energy
  2. Absorption of CO2 and reduction to organic materials (glucose, starch, fats, proteins, nucleic acids)
Other solutions
Symbiosis:
          Root nodules: nitrogen fixing bacteria (bean, pea, soya)
          Mikorrhiza: pine tree and fungi (root hair is substituted)
Parasitism: dodder (aranka), mistletoe (fagyöngy)
Carnivorous plants: not enough nitrogen in the soil – they trap insects (Drosera – harmatfű, Venus flytrap – Vénusz légycsapója)
Plant cell
Common cell organs:
          Cytoplasm
          Nucleus
          Nucleolus
          Endoplasmic reticulum
          Golgi apparatus
          Mitochondria
Only in plants:
          Chloroplast: photosynthesis
          Cell wall: protection
          Vacuole with cell sap: store (starch, oil)
          Inclusions (waste, crystals)
Levels of organization
          Cell association: in algae
          Thalloid plants: tasks are shared sometimes and partially (mosses)
          Vascular plants (tissued): tasks are shared in cells of tissues
Plant tissues
Meristematic tissue: dividing cells
          Apical: tips of the stem and root
          Interkalar: nodes in the stem (grasses)
          Cambium: to increase in diameter
Permanent tissues
Epidermis:
Single transparent layer of cells without chloroplasts
          Protects
          Decreases water loss
          Connection with environment
Specialities:
          Cuticle: protective waxy covering
          Stomata: guard cells contain chloroplasts. Inner wall is thicker. Water enters – swell up – pore opens (ventillation, H2O and CO2, O2 transport)
          Hairs: protection
          Rhizodermis: no stomata, no cuticle, root hair cells (absorption of water and minerals)
Transport tissue
Xylem
          Carries water and minerals from the root to the leaves
          Tracheids: elongated dead cells with tapering ends (ferns, Gymnosperms)
          Vessels: tubes strengthened by lignin (no end-walls, mainly in Angiosperms)
          Xylem parenchyma: storing living cells
Phloem
          Carries organic materials produced by photosynthesis
          Sieve cells: sieve plates on the end walls (ferns, Gymnosperms)
          Sieve tube: an elongated rank of individual sieve tube cells
          Companion cells: help the sieve tube cells to survive
          Vascular bundles
Xylem: inside (adaxial)
Phloem: outside (abaxial)
Cambium: between them
          Closed vascular bundle: no cambium, can not grow
          Open vascular bundle: cambium exists, can grow
Wood stem
Closed cambium ring produces xylem inside and phloem outside
Xylem:
          Sapwood (szíjács): working xylem
          Heartwood (geszt): does not carry substances, filled with lignin, tannin and pigments
          Annual ring (growth ring): in spring and summer tubes with large diameter (light), in autumn small (dark)
Ground tissue
Táplálékkészítő (photosynthesis):
          Palisade mesophyl
          Spongy mesophyl
Víztároló: stores water (cacti)
Levegőtároló: stores air (water-plants)
Raktározó: stores substances (starch, oil, proteins)
Szilárdító: sclerenchyma (dead cells with thick cellulose and lignin cell walls), collenchyma (living cells)
Kiválasztó: excretion (waste crystals in the vacuole), secretion (nectar, resin)
Plant organs
Root
Tasks:
          Absorbs water and minerals
          Fixes the plant
          Stores substances
Structure
          Zone of cell division
          Zone of cell elongation
          Zone of cell differentiation (absorption)
          Zone of transport
Root modification: M 177/2
          Absorption
          Ions by active transport (needs energy)
          Water by osmosis after the ions (passive)
Root pressure: cells secrete ions into the xylem – water moves there by osmosis – positive hydrostatic pressure – water moves upwards
Types of the root system
          Tap root system (dicot plants)
          Fibrous root system (monocot plants)
Stem
Tasks:
          Keeps the plant organs
          Transports substances
Vascular bundles
          In dicots: form a ring
          In monocots: throughout the stem
Stem types: M180/1
Leaf
Parts:
          Blade
          Petiole
          Axil
Task: photosynthesis
Types: M181/2
Water transport in plants
Effects:
          Root pressure
          Evaporation in leaves
          Cohesion (interaction between water molecules)
          Adhesion (interaction between xylem vessels and water molecules – capillarity)
Distance: 150 m
Speed: 1-50 m/h
Transport of organic substances
In phloem:
          Sucrose
          Amino acids
          Other small organic molecules
Speed: some mm-dm/h
Respiration
          Gas exchange: between the plant and the environment
          Cellular respiration: oxidation of organic substances to CO2 and H2O to release energy
Respiratory quotient: RQ = CO2 eliminated / O2 consumed
          Carbohydrates: RQ=1
          Fats, proteins: RQ less than 1
Stomata:
          In the daytime: respiration + photosynthesis (O2 flows out, CO2 flows in, photosynthesis is more intensive)
          At night: only respiration (CO2 flows out, O2 flows in)
Storing in Plants
Stored substances:
          Water (cacti)
          Carbohydrates (rice, potato)
          Protein (soya)
          Oils (colza, sunflower, poppy)
Storing organs:
          Tap root (carrot)
          Rhizome (Iris)
          Stem tuber (potato)
          Bulb (onion)
          Flower (cauliflower)
Excretion, secretion
Excretion: waste
Secretion: useful substances (essential oils, resin)
To the environment: CO2, water vapor, essential oils
In vacuole or in cytoplasm:
          Crystals (CaCO3, Ca-oxalate)
          Waste substances
Moving
In the cell: flow of the cytoplasm
Growing: deflection to the light (plant hormones)
Turgor: if the cell gets water it swells up
Tropism: depends on the direction of stimulus
          Geotropism: root (+), stem (-)
          Phototropism: root (-), stem (+), sunflower (+)
          Tigmotropism: touch
          Thermotropism
          Hydrotropism
Nastia: does not depend on the direction of stimulus
          Tigmonastia: touch-me-not, mimosa
          Photonastia: flower opens
Plant hormones
Chemicals regulate plant growth
Auxin
          Is produced mainly in stem tip (apical meristeme)
          Stimulates cell growing in the stem
          Inhibits cell growing in the root
          Geotropism: auxin is transported at the bottom side (stem grows upwards, root grows downwards)
          Phototropism: auxin is decomposed on the light side (cells grow faster on the shadow side - deflection to the light)
Other hormones
          Gibberellins: stimulate cell elongation and flowering
          Cytokinins: stimulate cell division (work with auxin) (tissue culture)
          Ethene: stimulates fruit-ripening
          Abscisic acid: inhibiting hormon (shedding)
Reproduction
Asexual:
          One parent
          Offsprings are clones
          Large number of offsprings
Types:
          Spores: mosses, ferns
          Vegetative parts or organs (root – acacia, stem – strawberry, rhizome – Iris, stem tuber - potato, bulb – onion)
Artifical types: grafting (oltás), budding (szemzés)
Sexual reproduction
          Two parents
          Fertilization, fusing of gametes
          Offsprings are different
          Result: variety
Types:
          Spermium with flagellum: mosses
          Spermium with cilia: ferns
          Flower: reproduction doesn’t depend on water
Flower
Reproductive shoot, made of modified leaves
Parts:
Receptacle
Sepal
Petal
In Monocots: tepal (homogenous)
Stamen: anther, filament
Carpel: ovary, style, ovary
Monoecious (egylaki), dioecious (kétlaki) plants
Insect-pollinated, wind-pollinated plants
Development
Diploid cell: each chromosome is paired (2n, e.g. body cells)
Haploid cell: single chromosome set (n, e.g. gametes)
Cell division:
          Mitosis: number of chromosomes does not change (2n – 2n, n – n)
          Meiosis: number of chromosomes decreases (2n – n)
          Life cycle: alternation of generations (sporophyte – meiosis - spores – gametophyte – gametes – fertilization – zygote - sporophyte)
Mosses: gametophyte period is longer
Ferns: sporophyte period is longer
Flower plants:
Male gametophyte: pollen and pollen tube (sperm cells, tube nucleus)
Female gametophyte: embryo sac (egg cell, synergid cells, endosperm mother cell, antipodal cells)
Fruit
It is formed by the parts of the carpel after the fertilization
          Real and false fruit
          Simple and aggregate fruits
          Dry or fleshy fruits (M. p. 198)
Seed
          Embryo (radicle, plumule)
          Cotyledon/endosperm
          Seed coat
          Germination: after a dormancy period
Plant classification
Nonvascular plants – telepes növények: thalloid organs
          No tissues and real organs
          Absorb water through the whole body surface
          Reproduction: asexual with spores, sexual needs water
          They can tolerate drying out
Liverwort (májmoha)
Mosses: stemlike, rootlike, leaflike parts
Importance: pioneer plants, water regime controlling
Non-flowering vascular plants
          Tissues and organs: root, stem, leaf
          Real land plants: vascular tissue, stomata
          Reproduction: asexual with spores, sexual needs water
Club-mosses (korpafüvek)
Horsetails (zsurlók)
Ferns (páfrányok): rhizome
          Male fern (erdei pajzsika
 
 
Seedy vascular plants
          New organs: flower and seed
          Reproduction doesn’t depend on water
Gymnosperms (nyitvatermők törzse)
Seeds develop on the carpels (no closed ovary)
Conifers:
          Needle-like (pines, larches, spruces) or scale-like (sequoia, cedars) waxy leaves
          Resin, adaptation to the cold and dry climate
Species:
          Norway spruce -lucfenyő
          Scotch pine – erdei fenyő
          European larch – vörösfenyő
          Giant sequoia – hegyi mamutfenyő
Angiosperms – zárvatermők törzse
Root:
          Tap root system, fibrous root system
          Absorption zone: epidermal root hair cells
Stem:
          Woody or herbaceous
          Xylem vessels and sieve tube
Broad leaves
Flower
          Coloured petals, nectar – insect-pollination
          Carpel is closed – fruit - seed
Classes of the Angiosperms
Dicots:
          Taproot system
          Herbaceous or woody, branched stem
          Circulary arranged vascular bundles
          Branched veins in leaf
          Flower usually occurs in fours or fives, sepals and petals
          Two cotyledons in seeds
          Examples: oaks, roses, apple, beech tree, nut, pea, bean, sunflower, lettuce, cabbage, cauliflower
Monocots:
          Fibrous root system
          Herbaceous, unbranched stem
          Scattered vascular bundles
          Paralel veins in leaf
          Flower usually occurs in threes, tepals
          One cotyledon in seeds
          Examples: Lily, onion, Iris, Tulip, wheat, maize, rice, grasses, orchids, palms