Exam #4 Flashcards
what is a native plant
- a plant that naturally occurs in an indicated area (indigenous)
- has evolutionary adaptations to local conditions
non-native plants
- introduced intentionally or by accident
- may coexist with natives or may be invasive
What type of climate is southern California?
- mediterranean climate
mediterranean climate
- mild wet winters
- hot dry summers
Coastal Sage Scrub
- low-growing aromatic shrubs
Coastal Sage Scrub evolutionary adaptations
- drought-resistance: thin leaves, light coloration, trichomes, spreading shallow root system
- wildfire adaptations: terpenes- highly flammable, extensive seed bank
uses of Coastal Sage Scrub
- medicine
- cooking
- sewing supplies
- edible
Chaparral
- evergreen shrubs, bushes, and low-growing trees
Chaparral evolutionary adaptations
- drought-resistance: thick waxy cuticle, leathery leaves, deep tap roots
- wildfire adaptations: fire-resistant root crowns; rapid regrowth, thick seed coats
uses of Chaparral
- food
- medicinal tea
- dyes
- animal treatments
Riparian Habitat
- shrubs and trees found alongside streams, ponds, and lakes
uses of Riparian Habitats
- candy flavoring
- weaving material
- medicine
- hunting weapons
oak woodland
- predominantly oak trees; undergrowth ranges from open to grassland to chaparral to dense shrubs
uses of oak woodland
- thick bark is a good fire resister
- food
- medicine
- laxative
Mixed Conifer Forest
- mix of broadleaf trees and conifers (pines)
Grassland/Prairie
- herbaceous perennials; dominated by non-native species
Desert Scrub
- perennial shrubs, grasses, and trees with short-lived herbaceous plants
Desert Scrub evolutionary adaptations
- arid environments: CAM photosynthesis, modified leaves, water storage tissues
Coastal Salt Marsh
- wetland shrubs regularly flooded with tidal salt water
Coastal Salt Marsh evolutionary adaptations
- inundation (flooding) and high salinity: heavy stems, small leaves, ability to excrete salt
angiosperm life cycle (female gametophyte development)
- sporophyte is dominant
- Megasporocyte develops in ovule of flower bud
- Meiosis produces 4 megaspore nuclei
- Cell grows A LOT and 3 nuclei degenerate
- Remaining megaspore nucleus does mitosis 3x resulting in 8 1N nuclei in the same cell
- In megasporocyte, 3 nuclei migrate to top of the cell, 2 to the middle, and 3 to the bottom; top 3: antipodals - help with embryo nutrition; ultimately degenerate; middle 2: central cell nuclei - eventually become nutritive endosperm; bottom 3: 1 is an egg cell; 2 are synergids that help with fertilization
- Cell walls are put up between the nuclei
- Central cell nuclei may fuse into 2N cells; these 7 cells = female gametophyte
angiosperm life cycle (male gametophyte development)
- Within an anther, many microsporocytes undergo meiosis creating 4 microspores each (N)
- Microspores separate from each other
- Each microspore does mitosis producing: 1 vegetative cell with 1 generative cell inside
- Double wall develops around the two cells → pollen grain (male gametophyte); exine: outer wall of pollen; capable of promoting germination based on external stimuli
- Pollen is released from anther
angiosperm pollination and germination
- Pollen grain lands on stigma
- Pollen tube (tube cell) grows down style to ovule
- 2 sperm cells transported down pollen tube in cytoplasm of tube cell
angiosperm fertilization
- Pollen tube grows towards an opening in ovule called a micropyle
- Upon entry, pollen tube bursts one synergid, tube growth is halted and sperm released into ovule
- Double fertilization: one sperm fertilizes egg → 2N zygote, second sperm fuses with central cell nuclei → 3N endosperm nucleus
- Endosperm nucleus undergoes rapid mitosis, creating fleshy nutritive endosperm
- Embryo does mitosis to a pre-programmed point, then goes dormant
growth
division and enlargement of cells
differentiation
cells take on different forms that provide specific functions
development
coordination of growth and differentiation
what catalyzes growth and development processes
- enzymes encoded in genes
what environmental factors affects gene expression
- internal - nutrients, vitamins, & hormones
- external - water, minerals, gases, light, temp
Nutrients
- plant growth and maintenance
- obtained from air and soil
Vitamins
- Coenzymes - organic molecules; e- acceptors/donors
- made in membranes
Hormones
- Organic molecules that affect growth
- Produced in regions of active growth then transported where they’re needed
what activated hormones
trigger signal
what is pathway for a trigger signal
Environmental cue → hormone release & transport → hormone binds to receptor → cascade sequence in cells → enzyme produced or activated → response
5 major types of hormones
- auxins
- GA (gibberellin)
- cytokinins
- ABA (Abscisic Acid)
- ethylene (not a ring)
Auxins
- First type of plant hormone discovered
- Synthesized from tryptophan in young growth regions
- directional transport away from source - polar
- movement typically via parenchyma cells: active transport
effects of auxins
- cell division and enlargement
- stem growth and initiation of roots
- stimulate growth in cambium but inhibit lateral branching - delay fruit ripening, leaf and fruit abscission
- production/enhancement of other hormones
- higher concentrations can kill plants, although monocots less sensitive
Auxins Applications
- uniform flowering & fruit ripening
- prevention of premature fruit drop
- control of plant shape
- control of broadleaf weeds
Gibberellins
- most produced in inactive form
- Acetyl-CoA is precursor
- Produced in immature seeds, root and shoot tips, young leaves
- movement through vascular tissues
- Produced in fungi and expected in other plant groups
effects of Gibberellins
- break dormancy of seeds and buds
- increased stem growth, fruit size
- induce flowering (juvenile to adult)
- lower temp threshold for growth
- faster growth in dicots, some monocots; little effect on conifers
- auxins needed to maximize GA effects
Gibberellin application
- earlier seasonal lawn growth
- more rapid flower growth
- faster seed germination and increased crop yields
- increased internode length and grape size
- anti-GA growth retardants used to produce commercial flowers with thicker stronger stalks
- limited use due to expense
Cytokinins
- Synthesized in root tips and germinating seeds
- transport via vascular tissues and parenchyma cells
effects of cytokinins
- stimulate cell division; speed entry into mitosis when auxins also present
- stimulate cell enlargement, tissue differentiation, chloroplast development, and cotyledon growth
- delay of auxin- & GA-related growth
cytokinins application
- prolonged veggie storage and freshness
- controlled height in ornamental shrubs
- shortened wheat height to reduce wind damage
- extended life of cut flowers
Abscisic Acid
- name referes to the belief that ABA causes abscission layers in fruits and leaves (not true)
- Synthesized from carotenoids in plastids
- Produced in mature leaves, dormant buds
- transport primarily through phloem: nonpolar
effects of ABA
- seed dormancy
- growth inhibitor; blocks auxin- and GA- induced growth
- prevents germination of seeds while fruit on plant
- response to excessive water loss and drought causes stomata to close
- increased root growth & water uptake
Ethylene
- Methionine precursor
- Oxygen required for production
- Produced in flowers, fruits, seeds, leaves, roots
- diffuses through plasma membranes
- Present in several fungi and bacteria
effect of Ethylene
- flower opening
- fruit ripening
- leaf and fruit abscission, senesence (death of tissue)
- thigmomorphogenesis - alteration of plant growth in response to touch
ethylene Applications
- ripening/color of commercial fruit; flowering management of harvested fruit
- unripe fruit can remain metabolically inactive in oxygen-free cold storage
- batch application of ethylene stimulates ripening
Oligosaccharins
- released from cell walls
- highly specific
- promote growth; inhibit flowering
Brassinosteroids
- produced in ER of pollen, immature seeds, roots, flowers
- normal growth, apical dominance, gravitropism
Apical dominance
- suppression of lateral bud growth
- auxin-like inhibitor in terminal bud
- decreased effect with distance from inhibitor source
- cytokinin application can stimulate axillary bud growth
Senescence
- breakdown of cell components and membranes
- leaf abscission
- death of aboveground parts of herbaceous perennials
- promoted by ethylene & abscisic acid
- delayed by auxins, gibberellins, and cytokinins
nutations
- spiraling growth of plant tip in climbing plants; increased chance of finding support
Twining
in climbing plants
Nodding
- oscillating movement of bent hypocotyl; aids in seedling movement through soil
Contraction
- contractile roots pull bulbs to more moderate temperature level
Nastic
- alternate bending up and down
Phototropism
movements in response to light
Gravitropism
movements in response to gravity
Thigmotropism
movements in response to touch
Turgor Movements
Changes in water pressure; often due to external contact
Sleep” movements
- folding of leaves or petals in regular daily cycles
- common in Fabaceae
solar tracking
- orientation related to sun
- Water conservation
Photoperiodism
- Differences in growth due to seasonal changes in day length
Quiescence
seed cannot germinate without normal growth conditions
Dormancy
- slowed cell metabolism in prep for winter, even when normal growth conditions are met
Charles Darwin
On the Origin of Species
theory
explains how a nature phenomenon occurs; incorporates numerous hypothesis that have been rigorously tested
law
universal truth; describes the phenomenon but doesn’t provide explanation
theory of evolution
all existing species descended from a common ancestor
theory of evolution basic tenets
- more offspring are produced than can survive
- offspring display variations in phenotype that are heritable
- individuals with traits better suited to the environment are more likely to pass those traits down
- over time more helpful traits will become more common in pop.
evolution
the change in allele (alternate versions of a gene) frequencies in a pop. over time
what are the 4 ways allele frequencies can change
- natural selection
- mutation
- genetic drift
- gene flow
Natural Selection
those best suited for the environment have a higher probability of survival and successful reproduction
what are the 3 modes of natural selection
- directional selection
- Disruptive selection
- Stabilizing selection
directional selection
one extreme phenotype is favored
Disruptive selection
both extreme phenotypes are favored
Stabilizing selection
average phenotype is favored
what are the 3 trends of natural selection
- Coevolution
- Adaptive radiation
- Convergent evolution
Coevolution
when one species evolves in response to another species evolving
Adaptive radiation
members of a lineage acquire different characteristics to adapt to different environments
Convergent evolution
distantly-related lineages acquire similar characteristics to adapt to similar environments
Mutation
an error in copying DNA
if a mutation is silent what could be the situation
- mutation in non-coding DNA
- mutation doesn’t affect protein shape
- “wobbly” 3rd base
Genetic Drift
- random chance and sampling error
- alleles not passed on due to death or lack of reproduction
- more likely to affect small populations
genetic drift founder effect
- small subset in new environment
genetic drift bottleneck effect
- small subset of survivors
gene flow
- movement of alleles between pop.
Punctuated equilibrium
- years of rapid and dramatic evolution, then very many years of none
Gradualism
- constant tiny evolutionary events
Speciation
- the creation of new species
- the opposite of species extinction
- requires genetic isolation
categories of isolation
- Prezygotic
2. Postzygotic
prezygotic
occurs before zygote is formed
postzygotic
occurs after zygote is formed
Prezygotic Isolation- geographic isolation
- pollen can’t physically get to the other population
Prezygotic Isolation- ecological isolation
- timing of bloom is misaligned
Prezygotic Isolation- mechanical isolation
- pollen receptors on stigma don’t fit with exine of pollen grain
Postzygotic Isolation- zygote death
- zygote cannot survive due to chromosomal mismatch
Postzygotic Isolation- hybrid sterility
- plant cannot produce viable gametes (possibly due to chromosomal mismatch)
Postzygotic Isolation- reduced hybrid fitness
- hybrid is not as well- adapted to the environment as parentals
Polyploidy
2 or more sets of chromosomes
what is the benefit to being polyploidy
increased chance of hybrid survival due to redundant genes from each parental
autopolyploidy
plants are hybrids of 2 populations but same species
allopolyploidy
plants are hybrids of 2 different species
Ecology
the study of the relationships and interactions of organisms with each other and with their environment
Population Ecology
studies organisms of the same species that interact with one another
“Big Bang” strategy
put all energy into reproduction then die
Repeated reproduction strategy
grow first, reproduce later many times
Phenology
study of the timing of events in a plant’s life
Populations exponential growth
- as population size (N)increases, growth rate increases→ doubling
- time decreases; cannot continue indefinitely
Populations logistic growth
- as population size (N) approaches K (max pop.), growth rate decreases
Density-independent factors
don’t get more intense and frequent as N increases
Density-dependent factors
get more intense and frequent as N increases
Community Ecology
studies populations of an area that interact with one another
2 results of competition
- local extinction of the loser; competitive exclusion principle
- niche partitioning- differential use of resources to allow both competitors to survive
ecological niche
has all resources needed by an organism to survive
intraspecific competition
among members of the same species
interspecific competition
among members of different species
Predator/prey interactions
predator controls the prey population, prey control the predator population
Symbiosis
an extended, intimate relationship between 2 organisms of different species
Mutualism
each symbiont benefit
Commensalism
one symbiont benefits while the other is unaffected
Parasitism
one symbiont (parasite) benefits while the other (host) is harmed
Ecological Succession
Changing species composition in an ecological community over time
primary succession
growth where no veg previously existed
secondary succession
re-growth in previously existing community following catastrophic event
Primary Succession chain
- pioneer community
- intermediate community
- climax community
Secondary Succession chain
- intermediate community
2. climax community
Ecosystem Ecology
studies communities within a larger environment including biotic & abiotic factors
what are the 2 main processes occurs in ecosystems
- flow of energy
2. cycling of matter
Nutrient Cycling
Continuous transformation of matter between organic and inorganic forms
eutrophication
- accumulation of nutrients in water body leads to algae bloom and subsequent depletion of oxygen
