Chapter 10: plants Flashcards
Imbibition
Absorption of water by seed ~ breaks seed coat
Meristem
an area of plant takes place through repeated cell division
Apical meristem
Grows vertically ~ increases height Primary Growth (all plants)
Two types of meristem
Apical and lateral
Lateral meristem
Grows horizontally ~ increase width/thickness Secondary Growth (woody plants)
Three zones at apical meristem
Zone of division : constant division
Zone of elongation: absorption of water
Zone of maturation: differentiation into specific plant tissues
Vascular cambium:
ring of meristemic tissue located between primary xylen & phloem
- Cells produced outside ~ become secondary phloem
- Cells produced inside ~ become secondary xylem
Secondary Xylem:
along with pith ~ form wood.
- Constant production ~ forms growth rings
Secondary phloem:
bark, cork cambium, cork
- Replaces the older ones.
Cork cambium:
ring of meristemic beyond the phloem.
Ground tissue:
Parenchyma, Collenchyma, Sclerenchyma
Parenchyma:
Filler tissue
Collenchyma:
Extra support to plant
Sclerenchyma:
main structural support
Phloem
Transports sugars
- sieve & companion cells
Sieve
allows substances to flow through them
lack organelles
Companion cells
carries out metabolic functions
have organelles
* connected via plasmodesmata
Xylem
Transports water in unidirectional
- Tracheids & vessel elements
Tracheids
Overlap their tapered ends.
Form tracheid to tracheid through pits
Vessel elements:
Vessel to vessel through perforation
Both xylem & phloem arrange to form
Stele (central part of the root)
Pith
Tissue found in center of root or stem.
- Made up of parenchyma
Stores and transports materials.
Epidermis
waxy layer ~ cuticle
Root hairs
Increase surface area - greater water & nutrient uptakes.
Cuticle - limits evaporation
Symplastic pathway - water movement through cell’s cytoplasm
Apoplastic pathway - water movement outside the cell (cell wall)
Casparian strip
regulate type & amount of substance that can enter from roots to the rest of the plant.
- fatty, waxy substance ~ impenetrable.
Function of stomata
gas exchange (open & close)
Function of guard cells
control opening & closing of stomata
LOW CO2:
during daylight ~ open stomata - diffusion of K+ - creates a gradient - cell turgid (Hypotonic)
HIGH CO2:
night time ~ close stomata
HIGH TEMP:
Needs to prevent transpiration ~ close stomata
When cells becomes turgid –> what happens to guard cells
Change shape
Guard cells - flaccid
no gas exchange - cover stomata
2 types of Mesophyll
- Palisada mesophyll
2. Spongy Mesophyll
Palisada mesophyll
tightly packed cells - carry out photosynthesis
closer to upper epidermis
Spongy mesophyll
loosely packed cells - allow for gas exchange
closer to lower epidermis
Bundle sheath of cells
surround & protect vascular bundles
Important for C4 plants
Types of water movements in plants:
Transpiration
Capillary action
Root pressure
Transpirational pull:
water evaporates out through stomata
Cohesion:
Similar particles cling to one another
Capillary action
Adhesive force - different particle
- b/w water & xylem vessels
Root pressure:
pressure that builds up in plant’s roots
osmotic gradient - drives water into root.
Types of food movements in plants:
Pressure flow hypothesis
Pressure flow hypothesis:
movement of sugars in phloem b/c of water movement.
- Produce sugars in leaves –> load sugar in phloem –> increase sugar concentration –> creates a gradient–> pulls water from xylem into phloem –> creates a turgor pressure –> allows for bulk flow
Turgor pressure
Hypotonic (low outside, high inside)
Plasmolyzed pressure
Hypertonic (high outside, low inside)
Flaccid pressure
Isotonic
Bulk flow
movement of sugar & water from leaves down to roots
Plants hormones: (5)
Ethylene, Cytokinin, Gibberellins, Abscisic acid, Auxin
Ethylene
Increase ripening of fruit
Cytokinin
regulates cell division & differentiation
- Prevents senescence (aging) of plants
Gibberellins
Stem & shoot elongation
Eliminates dormancy
Produces fruit, leaf & fruit death.
Abscisic acid
In times of stress
Promotes seed dormancy, close stomata & inhibits growth
Auxin
Promotes growth, function with cytokinin
- Phototropism, Gravitropism. Thigmotropism
Phototropism
Growth towards light
Gravitropism
Growth opposite of gravity
Thigmotropism
Growth because of contact
Basic alternation of generation cycle steps: (9)
Spores, mitosis, gametophyte, gametes, fertilization, zygote, mitosis, sporophyte, meiosis
Homosporous
One type of spores
Heterosporous
Two types of spores: microspores (males), megaspores (females)
Bryophytes:
mosses, hornworts, liverworts Nonvascular, no roots Small & short - grow horizontally Found in moist habitats. Contain Rhizoids ~ water absorption & anchorage. Gametophyte dominated Flagellated sperm, spores dispersal unit
Tracheophytes:
Ferns, gymnosperms & angiosperms Vascular plants ~ contain phloem & xylem Tall- grow vertically Have roots ~ anchors Sporophyte stage dominated
Lycophytes, pterophytes - Seedless
Club moss, ferns & horsetails, quilworts
Ferns formed first during forest carboniferous period
Heterospores
Flagellated sperm
Angiosperm & gymnosperm - Seeds
Heterosporous A. Gymnosperm: - Seeds ~ not protected - Conifers (fir, spruce, aspen) - Do not have flagellated sperm - Wind dispersal - Sporophyte generation
B. Angiosperm:
- Seeds - protected
- Flowers bearing & produce fruit
- Do not have flagellated sperm
- Wind/animal dispersal
- Double fertilization (endosperm)
Monocots
Single cotyledon Parallel leaf veins Flowers multiple of 3's Scattered vascular bundles Fibrous root system
Dicots:
Two cotyledon Netted/branched leaf veins Flowers multiple of 4's or 5's Organized in circular vascular bundles Taproot
Nitrogen fixing bacteria:
fix nitrogen gas (N2) to ammonia (NH3) & Ammonium (NH4+)
Nitrifying bacteria
convert ammonia (NH3) & Ammonium (NH4+) to nitrile (CN) & nitrate (NO3-)
Detritus
death & decay of plants & animals
Denitrifying bacteria
Convert nitrate (NO3-) into nitrogen gas (N2)
