BSC 212 Final

What were some of the problems encountered by plants as they made the transition from sea to land?

-dehydration
-transportation
-desiccation
-ventilation
-gravity
-fertilization

How did early land plants overcome dehydration during the transition from sea to land?

developed waxy cuticle to prevent water loss through evaporation

How did early land plants overcome transportation issues during transition from sea to land?

-development of vascular system (xylem/phloem)
-root system

How did early land plants overcome desiccation during transition from sea to land?

development of tolerance to survive periods of dryness by entering dormant state

How did early land plants overcome ventilation issues during transition from sea to land?

development of stomata to facilitate gas exchange allowing CO2 to enter for PS and O2 to exit

How did early land plants overcome gravity issues during transition from sea to land?

-development of lignin to provide structural support, growth upright

How did early land plants overcome fertilization issues during transition from sea to land?

pollen/seeds developed so plants could reproduce without water

What 3 groups of plants are considered bryophytes?

-mosses
-liverworts
-hornworts

What value (economically, etc.) do early land plants have?

-moss: peat
-liverworts: prevent erosion, form soil
-hornworts: research
-lycopods: cosmetics, pill coating
-ferns: food, ornamentals
-horsetails: scrubbing sponge

What is plant awareness disparity?

The tendency of people to overlook or undervalue plants in their environment

What solutions/efforts have been made to help PAD?

-integrating early plant edu. for young people
-focus on the value of plants themselves & not just what they provide humans
-understand plant/pollinator interactions

When/where did Ag in the Fertile Crescent begin?

13-11,000 ya in the Middle East

What is meant by the Green Revolution?

Lead by Norman Borlaug: a project that combined dwarf, disease resistant plants & fertilizers to try to feed the masses in developing worlds

What is the Urban Heat Island Effect?

Areas that have higher energy costs, air pollution, & heat related illnesses due to natural landcover being replaced with pavement & buildings that retain heat

How do we reduce the UHIE?

-plant trees, grasses in barren areas, right of ways, under solar panel, etc.
-plant native, drought tolerant plants
-plants that encourage shade
-fun green improve. projects
-green roofs

What attributes of a neighborhood or city impact the level of tree cover? (Burghardt et al. 2022)

-poles
-underground utilities
-soil compaction
-accessibility to water
-cost
-perception
-diversity

What are ecosystem services?

a benefit that wildlife or ecosystems provide to people

What are provisioning services?

benefit that can be extracted
(i.e. food, oil, timber)

What are regulating services?

benefit from a process
(i.e. pollination, water, purification, erosion)

What are cultural services?

non-material benefit, source of cultural, social, recreational benefit

What are supporting services?

benefits that allow for continuation of other services
(i.e. nutrient cycling, water cycle, etc)

What are examples of plants that contribute to provisioning services?

-blueberries, wheat, rice for food
-oak/pine for firewood
-aloe vera for medicine

What are examples of plants that contribute to regulating services?

-trees absorb CO2
-willows stabilize soil, prevent erosion
-sunflowers attract pollinators for reproduction

What are examples of plants that contribute to cultural services?

-cherry blossoms are celebrated in Japan
-maple trees signify fall in north America
-native herbs important to medicine, spiritual

What are examples of plants that contribute to supporting services?

-legumes fix nitrogen (symbiotic relationship)
-prairie grasses stabilize soil
-coral reefs provide habitat for marine life, supports biodiversity

What is the difference between plasmodesma & desmotubule?

-plasmodema are channels that connect plant cells
-desmotubules are components within the channels that contribute to structure and selective transport

What is water potential & what value does the concept have for plant physiologist?

-stored energy of water, capacity to do work
-gives insight to water movement, nutrient uptake, stress responses, & growth regulation

What is osmotic potential?

the potential for water molecules to move from one area to another due to osmosis

What is pressure potential?

(turgor potential) the physical pressure exerted by water within plant cells

What is turgor pressure?

-hydrostatic pressure in plant cells
-result of osmosis and/or uptake of water

What are the 2 types of tracheary elements?

-tracheids
-vessel elements

How do tracheids & vessel elements differ?

-tracheids do not have perforations, and VEs do
-tracheids are not efficient water conductors, while VEs are due to their width
-tracheids are secure, while VEs are vulnerable to embolism

What is transpiration and why is it dubbed an "unavoidable evil"?

-loss of water by plants via stomata
-leads to water loss, but is vital for nutrient transport, and is inevitable

How does the cohesion-tension theory account for the movement of water to the top of tall trees?

water flows from high to low potential, creating a transpirational pull of water in through the xylem

What is the difference between sources vs. sinks?

-sources are exporters of solutes
-sinks are importers that cannot meet nutritional needs

What is an example of a source & a sink for sucrose in a plant?

-source: leaves, produce sugars through PS
-sink: roots, require sugars for growth

How does the osmotically generated pressure-flow mechanism account for the movement of sugars from source to sink?

high pressure at the source and low pressure at the sink drives the movement of phloem sap from source to sink

What are the two types of sieve elements & how do they differ?

-sieve tube cells
-sieve elements

What is a meristem, and what is its composition?

plant stem cells capable of differentiating into specialized cell types such as apical, lateral, and intercalary
develop into various tissues & organs in plant

What are the three tissue systems of the plant body?

-dermal tissue
-ground tissue
-vascular tissue

What does the dermal tissue system consist of?

-epidermis
-periderm

How do parenchyma, collenchyma, and sclerenchyma cells differ from one another?

-P are living cells made of cellulose with large vacuoles
-C are living cells with thick walls made of cellulose & pectin, elongated
-S are dead at maturity, thick, lignified walls that are highly specialized & rigid

What does the vascular tissue system consist of?

-xylem
-phloem

What does the ground tissue system consist of?

-parenchyma
-collenchyma
-sclerenchyma

What are the functions of the collenchyma?

mechanical support and flexibility in growing regions (stems, leaves), withstand against stressors

What are the functions of the sclerenchyma?

structural support, protection (found in bark, hard stems)

What are the functions of the parenchyma?

photosynthesis, storage, secretion, gas exchange (found in leaves, stems, roots)

What are the principal conducting cells in the xylem?

tracheary elements:
-tracheids
-vessel elements

What are characteristics of the xylem?

-transports water/minerals from roots to rest of plant
-moving upward
-structural support

What are the principle conducting cells in the phloem?

-sieve tube elements: facilitate flow of nutrients, no nucleus
-companion cells: loading/unloading of sugars in sieve tubes

What are characteristics of the phloem?

-transports sugars, amino acids, lipids, proteins
-movement up & down

What is the mesophyll?

ground tissue between upper and lower epidermis
composed of parenchyma cells
main site of photosynthesis in green plants

How does secondary growth affect the primary body of the stem?

increases thickness of the stem to grow stronger & taller, forms bark, and enhances transport

What tissues are produced by the cork cambium, and what is the function of the periderm?

produces periderm which provides protection, insulation, gas exchange, and wound healing

What is bark, and how does its composition change during the life of a woody plant?

-outermost layer of stems/roots in woody plants
-periderm replaces epidermis through growth
-outer bark thickens through maturity, dead layers of cork & phloem accumulate

what are the principle differences between C3, C4, and CAM pathways for carbon fixation?

C3:

-uses rubisco

-low energy cost

-plants in cool/wet envir.

-prone to PR

C4:

-uses PEP carboxylase

-high energy cost

-plants in tropical envir.

-spatial sep avoids PR

CAM:

-temporal sep avoids PR

-stomata opens at night to reduce water loss

what are the similarities between C3, C4, and CAM pathways?

-C4 & CAM both use PEP carboxylase
-C4 & CAM both have low rates of PR

in what ways do C4 plants have an advantage over C3 plants?

spatial separation helps avoid photorespiration which C3 is prone to

explain temporal separation in CAM plants

at night CAM plants open their stomata for CO2 intake which is then converted to malic acid & stored in vacuoles

during day, stomata closes to minimize water loss: stored malic acid broken down to release CO2 used for the calvin cycle

why might CAM plants taste sweet during the day and sour at night?

during night, CO2 converted to organic acids
during day, acids break down to release CO2, sugars prod. during PS

what is the balanced equation for photosynthesis?

6CO2 + H2O -> C6H12O6 + 6O2

what is the overall equation for cellular respiration?

C6H12O6 + 6O2 -> 6CO2 + 6H2O + energy (ATP)

what is the principle function of cellular respiration?

shifting stored energy to usable energy

by what mechanism do plants respond to light?

phototropism: shoot, petiole growth toward light

by what mechanism do plants respond to gravity?

gravitropism:
root growth downward, shoot growth upward

by what mechanism do plants respond to a moisture gradient?

hydrotropism

why is it important that plants be able to "tell time"?

photoperiodism allows plants to undergo seasonal & developmental changes: some plants have to reach certain level of maturity before flowering, and others respond to photoperiod when seedlings

what are some characteristics of the circadian clock in plants?

-used to coordinate daily events & allow response to changing seasons by measuring daylength

-entrainment: periodic repetition of light & dark synchronize w/ an external factor

what is the effect of daylength on flowering?

short-day plants (early spring, fall) flower during LP shorter than critical length

long-day plants (summer) flower in LP longer than critical length

day-neutral plants flower regardless of LP

what advantages do molecular techniques have over comparative morphology & anatomy in assessing phylogenetic relationships?

they are easier to quantify, have the potential to provide many more characters for phylogenetic analysis, and allow comparison of organisms that are morphologically very different

how do we classify organisms?

-cladistics: analyzes branching, produces cladogram

-molecular systematics: phylogenetic trees, DNA barcoding

what is taxonomy?

the science of naming and classifying organisms by organizing species into hierarchical groups based on shared characteristics & evolutionary relationships

what is a fruit?

the matured ovary, often accompanied by accessory tissue which clings to the ovary when matured

what is a seed?

matured embryo, stored food, protective seed coat

what is embryogenesis?

formation of the embryo, establishes a body plan for the plant

how does the apical cell divide?

many times to become the embryo proper

what does the basal cell become?

the suspensor

what is the cotyledon?

embryonic leaf, first leaves to appear when seeds germinate

what does germination depend on?

water, oxygen, temp, light, seed coat rigidity, embryo dormancy by abscisic acid & gibberellic acid

what occurs during germination?

-primary root emerges
-epigeous or hypogeous stem emerges based on species

what is the epigeous stem?

cotyledons are carried out of the ground

what is the hypogenous stem?

cotyledons remain underground

what are breeding systems?

methods by which plant reproduce sexually

what are the 2 types of reproduction?

1) asexual
2) sexual

what is asexual reproduction?

vegetative (mitosis) the stolon & rhizomes

what is sexual reproduction?

alteration of meiosis & fertilization
-selfing
-outcrossing

what are the pros of asexual reproduction?

-reproduce quickly
-facilitate survival when difficult to find mates

what are the cons of asexual reproduction?

-deleterious genes do major damage
-genetically constrained

what are the pros of sexual reproduction?

-faster to obtain new favorable mutations (recombination during meiosis)
-novel genotypes: mating with populations & migration
-red queen hypothesis: host populations are continually evolving in response to pathogens
-avoiding mueller's ratchet: accumulation of deleterious mutation (via genetic recombination w/ natural selection)

what are the cons of sexual reproduction?

costly process

what are deleterious genes?

detrimental sequence of nucleotides forming the chromosome

what is a monoecious plant?

male & female organs on one plant (hermaphroditic)

what is a dioecious plant?

plants with male organs & plants with female organs

what is a gynodioecious plant?

plants with female organs & plants with male and female organs

what is a androdiecious plant?

plants with male organs & plants with male and female organs

what are the 3 drivers that affect the frequency of female plants in a population?

1) genetic drift: greater unpredictability in female frequency
2) nutrients in soil: more nutrients, more females
3) soil microbial community

what is chasmogamous?

open flowers

what is cleistogamous?

closed flowers, must self-pollinate

what is a protandrous plant?

male organs come to maturity before the female

what is a protogynous plant?

female organs come to maturity before the male