Biology - Chapter 10: Plants Flashcards
Seed coat
Hard outer layer that covers and protects the seed
Endosperm
Storage material, provides the embryo with nutrients
Embryo Parts
1) Radicle - develops into root
2) Hypocotyl - bottom region of young shoot
3) Plumule - develops into leaves
4) Epicotyl - shoot tip
Germination
Sprouting of a seedling from dormant state when environmental conditions are favorable
Meristems
Where plant growth takes place (via mitosis)
Primary growth
Vertical growth occurring at apical meristems
Root tip growth zones
- Zone of division
- Zone of elongation
- Zone of maturation
Secondary growth
Horizontal growth occurring at lateral meristems. Only occurs in woody plants.
Vascular cambium
Ring of meristematic tissue located between primary xylem and primary phloem
Cork cambium
Ring of meristematic tissue located outside in the phloem, produces cork, outermost protective layer
Ground tissue
provides structural support, makes up most of plant’s mass
Parenchyma
Filler tissue, makes up bulk of plant, thin cell walls
Collenchyma
Extra support, irregular cell walls
Sclerenchyma
Provides main structural support, thick cell walls
Vascular tissue
Transports materials from source to sink
Phloem
- Transport sugars from leaves to roots
- Made of sieve cells and companion cells
Sieve cells
Form a tunnel for transport, no organelles
Companion cells
Connected to sieve cells, contain organelles
Xylem
- Transports water from roots to leave
- Made of tracheids and vessel elements
Tracheids
Long and thin, water travels through pits in their tapered ends
Vessel elements
Short and stout, water travels via perforations in cell walls
Dermal Tissue
Outer layer of the plant, provides protection and regulation
Epidermis
Covered by waxy layer which prevents water evaporation
Root hairs
Increase surface area of roots for greater nutrient and water uptake
Symplastic pathway
Inside the cell’s cytoplasm, Water uptake in the roots
Apoplastic pathway
Outside the cell through cell walls, Water uptake in the roots
Stomata
- In the lower epidermis
- Open and close allowing for gas exchange
- Surrounded by guard cells
Stomata are closed when…
… CO2 concentration and temperature are high
Stomata are open when…
… CO2 concentratioon is low
Desiccation
Water loss
Palisade mesophyll
Closer to upper epidermis, tightly packed cells that carry out photosynthesis
Spongy mesophyll
Closer to lower epidermis, loosely packed allowing for gas exchange
Bundle sheath cells
Surround and protect the vascular bundle
Cohesion-tension theory
- Transpiration causes water to evaporate from stomata and leads to a transpirational pull
- This cohesive force pulls water column upward
Capillary action
Adhesive force due to attraction between water and xylem vessels causes water to climb upwards
Root pressure
Build up in roots, causing a osmotic gradient that drives water from soil into the roots
Pressure flow hypothesis
- Source cells produce sugar and load it into phloem
- Increased sugar concentration creates a gradient pulling water into phloem
- Turgor pressure in phloem increases, resulting in bulk flow movement of sugar from leaves down to roots
Ethylene
Gas that increases fruit ripening
Auxins
Cause cell growth in certain directions (tropism)
Phototropism
growth towards light
Gravitropism
growth away from pull of gravity
Thigmotropism
growth in response to contact
Cytokinins
Regulate cell differentiation and division with auxins
Gibberellins
Stem and shoot elongation, flowering, leaf and fruit death
Abscisic Acid
Functions during stress
Alternation of Generation
2 haploid gametes fuse, produce diploid zygote –> zygote becomes sporophyte via mitosis –> produces haploid spores via meiosis –> spore becomes gametophyte via mitosis–> gametophyte produces gametes
Homosporous Plants
Bisexual gametophyte, produces one type of spore
Heterosporous Plants
Produce two types of spores:
1) Microspores (male)
2) Megaspores (female)
Bryophytes
- Nonvascular plants: small and short
- e.g.: mosses, hornworts, liverworts
- Contain rhizoids (water-absorption hairs)
- Majority of life spent in gametophyte stage
- Reduced sporophyte which is attached to gametophyte
Tracheophytes
- Vascular: growth vertically and tall, have root system!
- Spend most of life cycle in sporophyte stage
- Include seedless
- Include seed-bearing (gymnosperms and angiosperms)
Seedless Tracheophytes
- Mostly heterosporous with flagellated sperm
- Lycophytes and pterophytes
- e.g. club moss, quillworts, fern, horsetail
Seed-bearing Tracheophytes
- All heterosporous
- Gymnosperms and Angiosperms
Gymnosperms
- Unprotected seeds
- e.g. conifers, spruce, redwood
- Sperm is not flagellated and is dispersed in seeds by wind
Angiosperms
- Most abundant plant
- Flower bearing and produce fruit from plant ovary
- Sperm is not flagellated and is dispersed by wind and animals, often as pollen
- Can exhibit double fertilization
Flower Structure
- Petals
- Stamen (male sex organ): composed of anther and filaments
- Pistil (female sex organ): composed of stigma, style and ovary
Fertilization
Pollen lands on stigma –> tube cell elongates down style forming pollen tube –> generative cell travels down pollen tube to ovary –> splits forming two sperm cells
Angiosperm: Cotyledons
First leaves to appear on seedling. Contain nutrients from seed to feed growing seedling
Angiosperm: Monocots
- Single cotyledon
- Long narrow lead, parallel veins
- Vascular bundles scattered
- Floral parts in multiples of 3
Angiosperm: Dicots
- Two cotyledon
- Broad leaf, network of veins
- Vascular bundles in ring
- Floral parts in multiples of 4 or 5
Nitrogen Fixation
-Plants have symbiotic relationship with nitrogen-fixing bacteria
Nitrogen fixing bacteria
- in root nodules of legumes
- fix atmospheric nitrogen to ammonia and ammonium
Nitrifying bacteria
-convert ammonia and ammonium to nitrites and then to nitrates
