Module 1 Flashcards
Plant Form and Function
evolutionary group of plants with the most species
angiosperms (approx. 270,000 species)
examples of primary meristems, and their locations
- shoot apical meristem (SAM): found at shoots
- root apical meristem (RAM): found at roots
distance bryophyte spermatozoids can travel
2-20m
definition of meristem
a group of meristematic cells (undifferentiated plant cells); “plant stem cells”
the diploid structure that supports the sporophyte
the seta
the oldest organism and its age
bristlecone pines; 5,067 years old
photosynthesis in heat
when it is too hot, there is damage to the photosynthetic apparatus
life cycle of gymnosperms
- A mature diploid gymnosperm sporophyte contains diploid cones.
- Meiosis occurs; haploid pollen grains form in the male cone (male gametophyte).
- Pollen sacs in the male cone open, releasing pollen. Pollen grains have “airbags” that assist with transport.
- Pollen lands on ovules in female cones (female gametophyte).
- When pollen grains come into contact with the haploid eggs within the ovule, they fertilize and produce a diploid zygote.
- Mitosis occurs; the zygote forms an embryo.
- Mitosis continues; the female cone grows.
- Mitosis continues; seeds form.
- As seeds germinate, they become seedlings; developing shoots and roots.
- The seedlings become sporophytes.
how flowers attract hummingbirds
- flowers are often red or yellow, as hummingbirds have a good sense of colour
- flowers often produce little to no odour, as hummingbirds have a bad sense of smell
- more fluid nectar is produced than for insects, as hummingbirds’ tongues act as a sponge to soak up nectar
- a long, tubular corolla is suited to the long beak of the hummingbird, but is wider than for moths/butterflies
evolutionary interpretation of plant life cycles: dependence on water
- bryophytes have a huge dependence on water (no cuticle)
- lycophytes/ferns have an intermediate dependence on water (cuticle on dominant generation, no cuticle on prothallium)
- angiosperms/gymnosperms have a low dependence on water (pollen viable when dry, cuticle on dominant generation, protected seeds)
function of epidermal platelets
- flattened “umbrella” shape (e.g. Silverberry, Elaeagnus)
- act as defense against heat
the meaning of “conifer”
cone bearer
six key evolutionary inventions in plants
- cuticles and stoma in vascular plants
- vascular system in vascular plants
- seeds in seed plants
- wood in seed plants
- flowers in angiosperms
- double fertilization in angiosperms
the best study plant (the “lab rat” of plants)
Arabidopsis
examples of ballistochoric plants
- squirting cucumber
- jewelweed (touch-me-not)
the pollination of sage
spatial and temporal separation
* younger flowers (near the top) are in the male phase; as the bee reaches into the flower to get the nectar, the anther acts as a lever, and deposits pollen on the bee’s butt
* over time, the style elongates, and anthers wither away
* older flowers (near the bottom) are in the female phase; as the bee reaches into the flower to get the nectar, the style acts as a lever, and picks up the pollen on the bee’s butt
self-incompatibility
* stigma biochemically recognize the pollen’s surface to avoid selfing
three types of simple tissues
- parenchyma
- collenchyma
- sclerenchyma
features of early lycophytes
- consistent presence of cuticles
- stoma
- vascular tissue; ancient lycophyte guard cells similar to stoma of modern-day angiosperms and gymnosperms
three types of photosynthetic pathways
C3, C4, CAM
C4 leaf anatomy
Kranz anatomy
Xylem and phloem must be… (in close proximity or far away).
in close proximity
Charcoal is made up of…
fossilized layers of lycophytes/ferns
ideal CAM photosynthesis conditions
- arid habitats
- 30-35°C
purpose of potassium in plants
- sugar/starch production
- fruit size and quality
- plant disease resistance
- enzyme activation and photosynthesis
- stomatal control
The majority of the angiosperm/gymnosperm life cycle is spent in the…
sporophytic generation
mychorrizae
- association between plant roots and soil fungi; the fungus grows on the outside of the root, as it cannot penetrate the endodermis
- “myco” means “fungi” and “rhiza” mens “root” in Greek
five types of gymnosperms, and approximate number of species
- conifers (900 species)
- Ephedra (35 species)
- Gnetum (35 species)
- gingko (1 specie)
- Welwitschia (1 specie)
composition and location of ground tissue
- often parenchyma, sometimes collenchyma, rarely sclerenchyma
- found in non-woody plants
temporal separation of carbon fixation in CAM plants
- stomata closed during the warmer hours of the day; RuBisCo (Calvin cycle) fixes carbon
- stomata open during the cooler hours of the night; PEP carboxylase (C4 cycle) fixes carbon
- promotes the least water loss
systemic vs. induced defense
- systemic defense: always present
- induced defense: activated in the moment
the flower organ that stores nectar
spurs
epidermal adaptations in Venus flytraps
six specialized epidermal hairs sense movement and shut closed to trap insects
epidermal glands and hemp (Cannabis sativa)
- male cannabis plants secrete huge amounts of pollen grains, whereas female cannabis plants consist of very limited numbers of eggs
- female cannabis plants are, hence, much more precious than male cannabis plants, and contain more glands
function of collenchyma cells
flexible support of the plant, especially in growing parts (e.g. young stems, roots, petioles, vascular bundles)
the four whorls of a flower (bottom to top)
- sepals (0, 3, 4, 5, or many)
- petals (0, 3, 4, 5, or many)
- stamen (0 to many)
- pistils (0 to many
structure of a flower
- sepals
- petals
- stamen (anther and filament)
- carpel and pistil (stigma, style and ovary)
three ways to avoid inbreeding
- temporal separation
- spatial separation
- self-incompatibility
two different tissues of differentiated plant cells
- simple tissue: made up of one cell type
- complex tissue: made up of more than one cell type
advantages of mychorrizae
- resistance to pathogens
- increased salt/drought tolerance
- increased nitrogen and phosphorus uptake
- increased growth
life cycle of apple trees (angiosperms)
- A mature diploid apple tree sporophyte contains diploid flowers.
- Meiosis occurs; haploid pollen grains form in the anther (male gametophyte).
- Pollen sacs in the anthers open, releasing pollen. Pollen grains have “airbags” that assist with transport.
- Pollen lands on the stigma, travels down the style, and into the ovary (female gametophyte).
- When pollen grains come into contact with the haploid eggs within the ovary, they fertilize and produce a diploid zygote.
- Mitosis occurs; the zygote develops into an embryo.
- Mitosis continues; the layers around the ovary swell, forming a developing diploid apple.
- Mitosis continues; seeds form.
- As seeds germinate, they become seedlings; developing shoots and roots.
- The seedlings become mature diplod apple trees.
the major difference between animal and plant growth
- animals grow more predictably than plants (determinate animal growth; indeterminate plant growth)
- animals begin with all their organs, whereas plants obtain more organs over time
the composition of bark
- phloem
- phloem ray
- cortex
- cork cambium
- cork
purpose of secondary growth in plants
- increases girth of root or stem, through secondary meristems
- the vascular cambium produces new xylem and phloem every year
- xylem of year 2 leads to an increased circumference and increase pressure on phloem; without adjustment, the outer portion of the stem would rip apart
characteristics of wind-pollinated flowers
- small
- no colours
- no nectar
- long filaments and styles
- large quantity of pollen produced (cheap, but not efficient as not much pollen reaches the stigma)
CAM mesophyll cells have large…
vacuoles
adhesion/cohesion and the concavity of the meniscus
- if the adhesive forces are greater than the cohesive forces, the meniscus is concave
- if the cohesive forces are greater than the adhesive forces, the meniscus is convex
composition of mitotic cell division in shoots (outside to inside)
- leaf primordia
- shoot apical meristem
the element that is completely key to plant life
nitrogen
two types of water transport in roots
- apoplastic transport: water travels through cell walls; this method is quicker and less resistant to water flow
- symplastic transport: water travels through cells and plasmodesma of parenchyma
examples of plants with many carpels, many pistils, one ovary, and one ovule
- blackberry
- raspberry
these fruits have many seeds in little segments, and little hairs which are leftover styles/stigma
flow of sugar through plants
Sugars move from sources (high sugar concentration) to sinks (low sugar concentration).
photosynthetic areas/generations of the angiosperm/gymnosperm life cycle
the sporophytic generation
- tree leaves
- flower sepal
- developing shoots
composition of the periderm
- cork cambium
- cork cells
composition of vessel elements
- thick lignified cell walls (different possibilities of enforcement)
- more strongly enforced than tracheids, due to being wider (able to withstand more water pressure)
cheating flowers and bees
- certain flowers limit the cost of reproduction; they rely on the fact that there are more honest than cheating flowers, so the bees can’t learn which are which
- some orchids smell, touch, or look like female bees to attract males; as males try to mate with the plant, pollen is either left on or picked up from the bee
examples of plants with self-incompatibility
fruit trees: apples, pears, cherries, plums
life cycle of mosses (bryophytes)
- The haploid male antheridium produces haploid spermatozoids with flagellae (often 2 flagellae).
- When it rains, a thin water film covers over the male antheridium and female archegonium.
- Chemotaxis occurs; the spermatozoids sense chemical cues given off by the female archegonium, to find it and swim inside of it.
- The spermatozoid swims inside the haploid egg; fertilizing it and producing a diploid zygote.
- Mitosis occurs; the zygote forms an embryo.
- Mitosis continues; the embryo develops up out of the egg into a diploid sporophyte.
- Meiosis occurs; haploid spores form inside the diploid capsule.
- As spores leave the sporophyte (either by wind picking them up, or a pressurized capsule shooting them out), they germinate; forming haploid protonema.
- Mitosis occurs, and protonema develop into haploid gametophytes; 50% of spores carry genes for each sex (male and female).
- Gametophytes mature fully into either a haploid male antheridium, or a haploid female archegonium, depending on their genes.
what a prothallium is lacking, and its effect
- the fern/lycophyte prothallium has no cuticle
- it is prone to dessication, and can die easily; 2-3 weeks of constant moisture needed for fertilization
how pore size affects nutrient leaching
the smaller the pore size, the more likely adhesions/cohesion will tie water to pores, and the less likely nutrients will leach from the soil
two main problems that arise without seed dispersal
- parent-offspring competition for space and resources
- inbreeding depression
two mobile life cycle phases in the bryophyte life cycle
- wind-dependent dispersal in spores (long distance)
- water-dependent dispersal in spermatozoids (short distance)
three functions of ground tissue
- photosynthesis
- storage
- space filler
epidermal adaptations in lotus flowers
- upper surface of leaves needs to stay dry for gas exchange
- nodules on epidermis containing smaller nobs allow water drops to roll off the surface of lotus leaves
- the leaf surface is hydrophobic, self-cleaning, and self-drying
the phosphorus cycle
- When it rains, phosphate runoff from rocks is absorbed into the soil.
- Some phosphate is absorbed by plants, but most is leached into water.
- Phosphate precipiate settles to the bottom.
- Sedimentation occurs; new rocks form.
- Geological uplifting forms aboveground mountains/rocks from underwater sediment.
two major groups of angiosperms, and approximate number of species
- monocots (60,000 species)
- eudicots (200,000 species)
Conifers have the longest ____________________ of all plants.
gestational period (fertilization to seed release); 2 years
the biggest abiotic pollinator
wind
composition of the region of elongation (primary growth) in shoots (outside to inside)
- protoderm
- ground meristem
- procambium
examples of secondary meristems, and their locations
- axillary meristem (AxM): found at the axil, the base of the leaf stalk connected to the stem
- adventitious meristem (AdM): buds found across the entire plant
- vascular/cork cambium (VC): found at roots and stems
- lateral root meristem (LRM): found on the lateral side of roots and stems
examples of hydrochoric seeds
- sea beans
- coconuts
the Calvin cycle
- used by all three photosynthetic pathways (C3 plants use it solely; C4 and CAM plants use it alongside an upstream process)
- RuBisCo fixes carbon from CO2 to a 3-carbon molecule, forming a 6-carbon molecule
capillary action
- water moves upward in a small tube through adhesion (attraction between water and the tube walls) and cohesion (acttraction between water molecules
- the thinner the tube, the further the distance
the shortest and furthest dispersal distance
- barochory is the shortest (< 1 m)
- hydrochory is the furthest (up to 1000 km)
composition of the region of differentiation in roots (outside to inside)
- epidermis (with root hairs)
- cortex (mostly parenchyma)
- endoderm
- pericycle
- parenchyma
- primary phloem
- vascular cambium
- primary xylem
the three most limiting nutrients in soil under average conditions (the three nutrients usually found in fertilizers)
- nitrogen (N)
- phosphorus (P)
- potassium (K)
composition of the region of girth (secondary growth) in shoots (outside to inside)
- epidermis
- cork
- cork cambium
- phloem ray
function and qualities of root hairs
- soft, flimsy epidermal hairs found on roots
- best observed in new seedlings
- vital for water uptake
- short-lived (2-3 weeks)
function of epidermal hairs
- act as defense against herbivores and heat
- sometimes modified into stinging hairs (e.g. stinging nettle, Urtica dioica)
primary compounds vs. secondary compounds
- primary compounds: essential to normal cellular function and life in general; products of photosynthesis/protein synthesis (e.g. carbohydrates proteins, starches, cellulose, lignin)
- secondary compounds: used to be believed that they had no function and were simply “extra products of photosynthesis”, but are chemical weapons against herbivores
function of shoot apical meristem (SAM), and what it’s protected by
- the primary meristem responsible for a plant’s aboveground growth (e.g. leaves, stems, flowers)
- protected by leaf primordia (young leaves)
features of monocots vs. eudicots
MONOCOTS
- 1 cotyledon
- parallel leaf venation
- fibrous root system
- floral parts (petals, sepals) in multiples of 3
- scattered vascular bundles
- herbaceous
EUDICOTS
- 2 cotyledons
- branched leaf venation
- tap root system
- floral parts (petals, sepals) in multiples of 4 or 5
- vascular bundles in a ring
- both woody and herbaceous
The majority of the fern/lycophyte life cycle is spent in the…
sporophytic generation
how barochory and small animal dispersal works
Big, heavy seeds fall to the ground where animals (e.g. chipmunks, squirrels) can get at them. These seeds are starch-rich and oil-rich; a great source of food for said animals. When the animals want to survive the winter, they hide the seed in a process called “seed caching”. Some of these caches are forgotten; the seeds in these caches germinate and grow over time.
Barochoric seeds are produced in huge amounts, due to the low amount of seeds that make it on to the next generation.
characteristics of exozoochoric seeds
- downward hairs that latch onto fur, feathers, clothing, etc.
- role model for Velcro
how flowers increase likelihood of pollination through specialization
- floral architecture to optimize pollen uptake/deposition
- adaptation to pollinators’ senses for precise attraction (sight, smell, taste, touch)
- adaptation to food requirements of pollinators (fitting reward)
ancestor of plants
green algae
two types of insect-pollinated plants, based on pollinator specialization
- specialists rely on a narrow group of pollinators; sometimes, there is an “exclusive relationship” (one pollinator for one specie) which leads to a tight co-evolution
- generalists rely on a wide range of pollinators
main purpose of self-incompatibility
selfing avoidance
ATP-dependent control in the endodermis
- ATP is needed for apoplastic water to enter the sympastic flow
- ATP is needed for sympastic water to re-enter the apoplastic flow
how flowers attract bees
- flowers are often yellow and blue, so the bee can see (bees see in UV); they are not red, as bees can’t see red
- “nectar guides” are lines that point towards the nectaries so bees can find the easiest access
- nectar is hidden in a way that only bees can access it; either a bee proboscis is needed to reach the nectar, or the strength of a bee is needed to open up the plant
the year that the periderm takes over the epidermis’ job of being the primary sealer of the stem
year 2
features of gymnosperms
- drought-resistant seeds with wings
- stoma
- vascular tissue
where wind pollination is most common
habitats with fewer insects or more wind
- higher latitudes/altitudes
- dry environments
- open vegetation
- island floras
Developing root hairs account for ____% of water uptake, whereas older, suberized root regions account for only ____% of water uptake.
> 95%, <5%
You can only count year rings in…
xylem, not phloem
Cations are ________ bioaccessible than anions.
more
how flowers attract moths
- flowers are often white or dull, with a strong smell often emitted after sunset (as moths are night-active)
- nectar is hidden in long narrow flower tubes, so only the long moth proboscis can reach it
Physical defense is often…
systemic
four types of vascular plants, and approximate number of species
- angiosperms (270,000 species)
- gymnosperms (900 species)
- ferns (12,000 species)
- lycophytes (1,200 species)
how flowers attract butterflies
- flowers are often red and orange
- nectar is hidden in long narrow flower tubes, so only the long butterfly proboscis can reach it
composition of xylem, and overall functions
- tracheids (transport, support); dead at maturity
- vessel members (transport, support); dead at maturity
- fibers (support); dead at maturity
- parenchyma (storage); alive
five examples of pollinators
- bees
- flies
- butterflies
- moths
- hummingbirds
the most common plant-animal interaction
herbivory
three photosynthetic pathways ranked from greatest to least productivity
C4 > C3 > CAM
how myrmecochory works
Myrmechoric seeds are covered in a fleshy, nutrient-rich, fat-rich “elaiosome”. Elaiosomes entice ants; they bring the seed back to the hive to feast and feed larvae. When the elaiosome has been eaten, ants serve no purpose for the remaining seed, so they throw it away (in a new location from where it was originally found).
Myrmecochory is a symbiotic relationship between plants and ants. The seeds provide the ants with food, and in return, the ants aid in seed dispersal.
function and properties of the carpel and its components
- composed of the stigma, style, and ovary
- the stigma is a sticky landing platform for pollen
- the style connects the stigma with the ovary
- the ovary can have one to many ovules, but an ovule only has one egg cell
cation uptake by root hairs
- Respiration takes place in root hairs; sugars are broken down to produce carbon dioxide.
- Carbon dioxide reacts with water in soil to form bicarbonate and a hydrogen cation (H+).
- As H+ has a higher affinity for negative bonding sites, it displaces mineral cations.
- Minerals are absorbed through specific ion channels in the root cell membrane.
examples of CAM plants
- desert plants
- succulents
- pineapple
- vanilla
- agave
evolutionary interpretation of life cycles: lengths of gametophytic/sporophytic life cycle phases
- over time, the gametophytic generation becomes shorter-lived (longest in bryophytes, shortest in angiosperms/gymnosperms)
- over time, the sporophytic generation becomes longer-lived (shortest in bryophytes, longest in angiosperms/gymnosperms)
key invention of flowers
pollination syndromes: pollinators assist in carrying pollen to other flowers
two different types of hoarding in small animal dispersal
- scatter hoarding: one or a few seeds per cache (e.g. blue jay); during the colder seasons, the part of the brain responsible for memorization in scatter hoarders grows, due to needing to remember the locations of hundreds of thousands of seeds
- larder hoarding: many seeds per cache (e.g. chipmunks); caches must be heavily defended, as if they are found, it could mean death for the animal
two main types of sclerenchyma
sclereids:
- short cells, often branched
- occur singly or aggregately
- found in hard seed coats, shells of nuts (make them hard), and pear flesh (gives grainy feel)
fibers:
- support stems
- found in flax plants
steps of double fertilization
- Inside the ovule, there is a diploid central cell and a haploid egg cell.
- As a pollen grain lands on the stigma, a haploid sperm nuclei travels down the style; it splits in two, via mitosis.
- One haploid sperm cell fertilizes the haploid egg cell, forming a diploid zygote, and the other haploid sperm cell fertilizes the diploid central cell, forming a triploid endosperm.
what “CAM” stands for
Crassulacean Acid Metabolism
characteristics of bryophytes, in comparison to vascular plants
- no vascular system results in no “backbone” to grow tall; bryophytes are often very small
- no true roots, only tiny filamentous rhizoids; rhizoids anchor bryophytes, but they are unable to uptake nutrients very efficiently
- no or very limited cuticle results in quick loss and uptake of water; bryophytes generally prefer it wet, but have adapted to survive dehydration
- very different life cycle
spatial separation of carbon fixation in C4 plants
- PEP carboxylase fixes carbon from CO2 into malate (4-carbon molecule) in mesophyll cells
- RuBisCo fixes carbon from CO2 into 3-carbon molecule in bundle-sheath cells; always a greater CO2 concentration than O2
- 12 ATP from C4 cycle + 54 ATP from C3 cycle
major function of phloem
continuous system transporting dissolved sugars from leaves to the rest of the plants (top-down)
water travel and composition of tracheids
- water flows through adjacent pits from cell to cell
- walls enforced with lignin
The majority of the bryophyte life cycle is spent in the…
gametophytic generation (haploid)
example of de-induced physical defense
- Holly plants produce thorned leaves to horde away herbivores, but this takes energy
- leaves that are taller (out of reach of herbivores) are produced without thornes to save on energy
jasmonic acid
- when a plant signals an imminent herbivore attack, jasmonic acid is released into the airstream and picked up on neighbouring plants
- neighbouring plants recognize this signal and prepare for attack (e.g. less seed production, higher toxin production)
how soil pH affects cation exchange capacity (CEC)
- more alkaline soil (high pH) means less H+, and more space for minerals
- more acidic soil (low pH) means more H+, less space for minerals, and more minerals washed away with rainwater
function of sclerenchyma cells
structural strength
composition of phloem, and overall functions
- sugar flows through sieve tube members, divided by sieve plates
- companion cells control both themselves and sieve tube members
why humus is a good soil
- undecomposed organic matter
- nutrient-rich
- high CEC
- light and fluffy
- high water-holding capacity
regions of growth in shoots and roots
- mitotic cell division
- region of elongation
- rgion of differentiation/maturation
the meaning of “angiosperm”
covered seeds: many tissues cover seeds to protect the embryo
All grasses are pollinated via…
wind
two pathways after double fertilization
- The endosperm exists until cotyledons start to photosynthesize. The cotyledons are then replaced by true leaves.
- Early in double fertilization, the endosperm is aborted; food is stored in cotyledons instead. The cotyledons become full of starch - turning a brown colour (e.g. common beans, chickpeas) - and due to a lack of space, are unable to photosynthesize. They are then replaced by the first true leaves.
transpiration in plants
- liquid water evaporates due to the sun’s heat
- water vapour exits the vascular bundle
- the result is a chain reaction, in which liquid water is pulled up the column of xylem throughout the plant
17% of flowers are of this sexual reproductive system (give examples)
monoecy
e.g. corn (male tassel, female ear), hazelnut
pressure-flow model of phloem (and xylem) translocation in the spring
- Dissolved sugars are stored over the winter in storage parenchyma (source).
- An ATP pump controlled by companion cells transports dissolved sugars through transport channels into sieve tube elements.
- Through osmosis, water moves from xylem to phloem.
- Water and dissolved sugars flow up sieve tube elements, from areas of high sugar concentration to low sugar concentration, with the help of transpirational pull.
- An ATP pump controlled by companion cells transports dissolved sugars through transport channels into growing tissues (sink).
- Water and dissolved minerals flow up xylem due to transpirational pull and cohesion.
- Water evaporates through stoma.
Generalistic plants are more…
opportunistic; multiple flowers make up landing platforms for insects of different sizes, and food is non-specialized
three types of lycophytes, and approximate number of species
- spikemosses (700 species)
- club mosses (400 species)
- quillworts (150 species)
relative elemental analysis of plants
- 96% is hydrogen, carbon, and oxygen from H2O or CO2
- 3.6% is various macronutrients from soil
- 0.4% is various micronutrients from soil
three factors limiting plant growth
- missing soil nutrients: roots struggle to find more nutrients in the same place
- meristematic slowdown: meristematic cells replicate slower with aging
- higher hydrolic pressure: the taller the plant, the further water has to travel; xylem can’t keep up, especially in warmer climates, leading to top dessication
characteristics of hydrochoric seeds
- hard seed coat for protection
- pocket of air inside for flotation
- food inside for germination
- usually found in tropics/shore edge
key invention of angiosperms
flowers
three functions of parenchyma cells
- space filler: parenchyma cells make up the bulk of a plant’s structure
- photosynthesis: chlorenchyma cells (parenchyma cells with chloroplasts) are responsible for photosynthesis, and are typically found in leaves
- storage: parenchyma are useful for storage of water and nutrients in roots, leaves, seeds, and fruits (e.g. they make apples juicy)
the percentage of plants that undergo C3 photosynthesis
85% (most angiosperms)
features of collenchyma cells
- alive; all organelles present
- thickened in cell corners
- elongated
photosynthetic areas/generations of the bryophyte life cycle
the gametophytic generation
- gametophyte
- protonema
how plants cool down
transpiration
four types of systemic physical defense
- thorns and spines
- trichome density: the thicker the trichomes, the more layers that need to be eaten down before reaching the leaf
- make-believe: fake insect eggs, fake bird droppings, and variegation (fake herbivory) are suggestive of previous visitation
- hiding: passive hiding (e.g. Lithops seeds look like the rocks in which they they reside (pebble plants)) and active hiding (e.g. sensitive plants fold to look like twigs when leaves are touched, via electric currents travelling through phloem
types of sexual reproductive systems in flowers
- hermaphroditism: a single plant is composed of flowers with both male and female organs (bisexual flowers, bisexual plant)
- monoecy: a single plant is composed of flowers with only male organs, and flowers with only female organs (unisexual flowers, bisexual plant)
- dioecy: a single plant is composed of only flowers with male organs, or only flowers with female organs (unisexual flowers, unisexual plant)
stele
the inside of the root
the ATP-driven pump in sugar flow
- ATP is needed to drive sugar from source cells into phloem cells
- ATP is needed to drive sugar from phloem cells into sink cells
- no ATP is needed within phloem, as the flow of sugar is drivin by a pressure-gradient (high sugar concentration to low sugar concentration)
different ways nitrogen is made bioaccessible to plants (the nitrogen cycle)
- rhizobacteria in legume root nodules fix nitrogen in legume roots
- when nitrogen-fixing bacteria in soil die, ammonium is released; ammonium is bioaccessible to plants
- when plants and animals die, decomposers absorb amino acids and proteins, and when decomposers die, ammonium is released; ammonium is bioaccessible to plants
- nitrifying bacteria nitrify ammonium into nitrates; nitrates are bioaccesible to plants
Phosphorus is mostly present as a(n) (cation/anion)…
anion
75% of flowers are of this sexual reproductive system (give examples)
hermaphroditism
e.g. trillium, evening primrose, raspberry, blue cohosh, arabidopsis
the amount of water needed for a plant per day
200 L/day (75 cm/min)
self-incompatibility explained
stigma biochemically recognize the pollen surface and ensure only outcross pollen (pollen from other flowers) fertilize the egg
flow direction in xylem and phloem
- xylem: water and minerals move up only
- phloem: water and food move may up or down, but only in one direction at a time
low productivity of CAM plants
despite being water efficient, CAM plants are only able to produce the maximum amount of malate that can be stored in vacuoles
tracheids vs. vessel elements
TRACHEIDS:
- narrow, long
- pointy
- evolutionary old; found in gymnosperms and angiosperms
- less efficient
VESSEL ELEMENTS:
- wide, short
- flattened
- evolutionary new; found in angiosperms
- more efficient
composition, location, and function of the Casparian strip
- a hydrophobic, waxy band made up of suberin found in the endodermis that controls what substances can permeate into xylem
- apoplastic water cannot pass through the Casparian strip, whereas symplastic water can go through
this is a process that all angiosperms start, but not all angiosperms finish
double fertilization
how berry seeds are spread (endozoochory)
As the fruit ripens, it is filled with nutrients and water. When it is fully ripe, the berry not only has a sweet, juicy taste, but it is also brightly coloured to attract animals.
Seeds are covered in a strong seed coat to survive chewing and digestion. When the animal poop out the seeds, the nutrients in the poop allow for the seeds to germinate and grow.
major function of xylem
continuous system transporting water and minerals from the roots to the rest of the plant (bottom-up)
evolutionary interpretation of plant life cycles: dependence on photosynthesis
- in bryophytes, the gametophyte is photosynthetic
- in lycophytes/ferns, the gametophyte and sporophyte are both photosynthetic
- in angiosperms/gymnosperms, the sporophyte is photosynthetic
Herbs and spices are examples of…
chemical weapons (secondary compounds)
the cation with the strongest affinity to negatively charged soil sites
H+
function and properties of sepals
- protect inner flower organs before the bud opens
- frequently green
- can be free, or fused to form tube
features and location of the epidermis
- one cell layer thick
- alive; all organelles present
- found in the roots, shoots, and leaves of non-woody plants
- upper and lower epidermis
another word for fertilization
syngamy
epidermal adaptations in rose flowers
- conical epidermal cells allow for light reflection
- roses look shiny and attract insect pollinators
Secondary growth only occurs in…
woody eudicots and conifers
composition of the region of differentiation in shoots (outside to inside)
- epidermis
- cortex (mostly parenchyma)
- sclerenchyma/collenchyma
- phloem
- vascular cambium
- xylem
- pith
gas exchange in C3 stoma
- when stomata opens, CO2 passively enters, O2 passively exits, and H2O exits via transpiration
- when stomata closes, there is a higher O2 concentration and a lower CO2 concentration
photosynthesis in the cold
when too cold, there is very little photosynthesis (slower metabolic reactions)
varied plant reproduction amongst the different sexual reproductive systems
dioecy
* outcrossing between plants
monoecy
* selfing between flowers of a single plant
* outcrossing between plants
hermaphroditism
* selfing within a single flower
* selfing between flowers of a single plant
* outcrossing between plants
main purpose of temporal and spatial separations
- gender specialization
- increase in fertilization efficiency; better pollen donors (male) and pollen recipients (female)
- less pollen is wasted, and more eggs are fertilized
features and function of the stomata
- composed of two bordering guard cells (specialized epidermis cells)
- made up of an outer thin wall and an inner thick wall
- aids in gas exchange and evaporation
- in dry conditions, there is low water pressure; water exits vacuoles, guard cells shrink, and the stomata closes
- in wet conditions, there is high water pressure; water enters vacuoles, guard cells swell, and the stomata opens
shading in CAM plants
platelets shield photosynthetic apparatus from intense heat
pressure-flow model of phloem (and xylem) translocation in the summer
- Dissolved sugars are produced by photosynthesis in chlorenchyma (source).
- An ATP pump controlled by companion cells transports dissolved sugars through transport channels into sieve tube elements.
- Through osmosis, water flows from xylem to phloem.
- Water and dissolved sugars flow down sieve tube elements, from areas of high sugar concentration to low sugar concentration.
- An ATP pump controlled by companion cells transports dissolved sugars through transport channels into storage parenchyma (sink).
- Through osmosis, water moves from phloem to xylem.
- Water and dissolved minerals flow up due to transpirational pull and cohesion.
- Water evaporates through stoma.
cation vs anion uptake
- cation uptake is through cation exchange
- anion uptake is doing from soil water solution, if dissolved
the hardest mineral for plants to take up
phosphorus: it is mostly biounavailable, as it is highly reactive and precipitates easily
CAM plants have a similar anatomy to…
C3 plants
photosynthetic areas of the lycophyte/fern life cycle
both the gametophytic and sporophytic generation
- prothallium (and gametophyte)
- frond sporophyte/mature leaf sporophyte
two plants with systemic chemical defense
- poison ivy: produces oil that produces a rash aggravated with sunlight
- stinging nettle: modified hairs are filled with chemicals that produce a rash
two mobile life cycle phases in the fern/lycophyte life cycle
- wind-dependent dispersal in spores (long distance)
- water-dependent dispersal in spermatozoids (short distance)
function of the periderm
- over time, the epidermis faces wear and tear; as the stems grow, the epidermis rips apart
- the periderm acts as further protection in long-living plants
how flowers attract flies
dull, white, or reddish flowers accompanied with a putrid smell make the flower appear like rotting flesh, used to feed larvae
flow chart of animal growth vs. plant growth
PLANTS:
undifferentiated cells → differentiated and undifferentiated cells → indeterminate growth
ANIMALS:
undifferentiated cells → differentiated cells → determinate growth
75% of fern species are found in the…
tropics
The life cycle of lycophytes is almost identical to that of…
ferns
key invention in gymnosperms
wood: the water-conducting system of xylem
grasses and induced physical defense
- silica makes grazing harder, but this takes energy
- when grasses are repeatedly grazed upon, they produce more silica over time
how secondary growth works
- as the vascular cambium produces more layers of xylem and phloem, cracks form
- the cortex forms the cork cambium
- the cork cambium forms cork rays to seal outer (stem) gaps and phloem rays to seal inner (phloem) gaps
soils in which nitrogen is more limited
nitrogen is more limited in younger soils as time is needed for bacteria to build up soil nitrogen content
e.g.
- sand dunes
- newly deglaciated areas
- volcanic soils
soil particle cation exchange
- soil particles have negatively charged binding sites for cations
- anions react with cations and precipitate
types of macromolecules
- nitrogen
- potassium
- calcium
- magnesium
- phosphorus
- sulphur
- silicon
examples of anemochoric adaptations
- hairs (e.g. milkweed, cottonwood)
- parachutes (e.g. dandelion)
- wings (e.g. winged maples)
carpel vs. pistils
carpels are the female reproductive part of the flower, whereas pistils are composed of one or many carpels
epidermal adaptations in pitcher plants
- modified star-shaped trichomes help insects climb up the outside of the pitcher
- slippery grooves and downward pointing teeth on the rim encourage insects to move inside the pitcher
- glands at the inner rim produce a sweet smell and slippery wax to attract and push insects down the pitcher
- slippery, overhanging epidermal cells inside the pitcher allow insects to easily crawl down, but make it almost impossible to climb up
- epidermal glands in the pitcher produce enzymes for insect digestion
two types of seed plants, and approximate number of species
- angiosperms (270,000 species)
- gymnosperms (900 species)
composition of mitotic cell division in roots (outside to inside)
- root cap
- root apical meristem
the backbone of plants
xylem
equation for photosynthesis
6CO2 + 6H2O → C6H12O6 + 6O2
xylem in gymnosperms vs. xylem in angiosperms
- in gymnosperms, xylem is simple tissue composed of only tracheids (softwood)
- in angiosperms, xylem is complex tissue composed of various elements (hardwood)
three types of epidermal trichomes
- hair (classic trichome, least evolved)
- gland (glandular trichome)
- platelet (flattened trichome, most evloved)
three types of bryophytes, and approximate number of species
- mosses (12,000 species)
- liverworts (6,000 species)
- hornworts (100 species)
two essential molecules made up of phosphorus
- nucleic acids
- energy currencies (ATP and NADP)
the mechanism of stoma control
- in wet conditions, K+ moves into guard cells via osmosis and ATP; the concentration of K+ in guard cells is greater than that in neighbouring epidermal cells
- in dry conditions K+ moves out of guard cells via osmosis and ATP; the concentration of K+ in guard cells is less than that in neighbouring epidermal cells
three types of ferns, and approximate number of species
- true ferns (12,000 species)
- horsetails (15 species)
- whisk ferns (2 species)
five types of complex plant tissue, and overall functions
- epidermis (protection, exchange, uptake)
- periderm (protection, exchange)
- xylem (transport, support, storage)
- phloem (transport)
- ground tissue (support, storage)
Stomatal transpiration accounts for ____% of water loss, whereas cuticular transpiration accounts for only ____% of water loss.
99%, <1%
6% of flowers are of this sexual reproductive system (give examples)
dioecy
e.g. hemp, asparagus
the four types of defense against herbivory
- systemic physical
- systemic chemical
- induced physical
- induced chemical
The internal architecture of herbs is achieved and kept through…
primary growth
the era of which bryophytes evolved
- we don’t exactly know when bryophytes appeared, as they are very small and don’t fossilize well
- they evolved after green algae
the best way to avoid selfing
self-incompatibility
composition of the epidermis, and overall functions
- epidermis cells (protection)
- cuticle (protection)
- stoma (water and gas exchange)
- trichomes; glands, hairs, and platelets (protection, uptake)
why selfing is bad
often leads to inbreeding depression
monarch butterfly adaptation to milkweed
- milkweed produces a toxin that causes a heart attack in small mammals
- monarch caterpillars/butterflies are immune to this toxin; they keep it within their bodies
- if birds are to prey upon the caterpillar/butterfly, it’ll ingest the toxin, and get sick
two mobile life cycle phases in the angiosperm/gymnosperm life cycle
- seed-dispersal syndromes in seeds (long distance)
- pollination syndromes in pollen (short distance)
four plants with induced chemcical defense
- corn: one hour after feeding, an enzyme is produced by the plant to inhibit caterpillars’ growth; as feeding persists, more enzyme is produced
- arctic grasses: after grazing, toxins are produced by the plant to inhibit lemmings’ digestive juices; as grazing persists, more enzyme is produced
- beans: when herbivourous mites start to feast, a volatile (gas) is produced; carnivorous mites sense this gas, know that there is food nearby, and feed on the herbivorous mites
- Cecropia tree: when bugs start to feast, a volatile (gas) and a nectar reward is produced; ants sense this gas, and defend the plant (ants know that nectar can ony be produced if the plant is kept alive)
two types of meristems
- primary meristems: shoot and root meristems
- secondary meristems: many different meristems in different locations
four essential molecules made up of nitrogen
- amino acids
- chlorophylls
- nucleic acids
- energy currencies (ATP and NADP)
when secondary growth begins
year 2
function and properties of petals
- colourful to attract pollinators
- can be free, or fused to form tube
function and properties of the stamen and its components
- the male reproductive part of the flower
- pollen-producing
- composed of the filament and the anther
- the anther is commonly composed of 4 pollen sacs
defining feature of hornworts
small horns (approx. 4-5 cm) are produced when ready for sexual reproduction
non-directed vs. directed pollination
- non-directed pollination is via abiotic factors that cannot be trained (i.e. wind, water)
- directed pollination is via biotic factors that can be trained (i.e. animals)
vascular tissue in primary growth (herbs) vs. secondary growth (trees, shrubs)
- in primary growth, vascular tissue is found in bundles
- in secondary growth, vascular tissue is found in a circular, continuous ring
Plants roots can only take up minerals that are…
dissolved
the three hypotheses on mechansims of water transport, and their distance limits
- capillary action: 1m
- root osmotic push: 3 m
- transpiration: 130 m
life cycle of ferns
- A mature diploid leaf sporophyte contains sori containing clusters of sporangia.
- Meiosis occurs; haploid spores form inside the diploid sporangium.
- As spores leave the sporophyte, they germinate; forming heart-shaped, haploid prothallium (gametophyte).
- Mitosis occurs; male antheridia and female archegonia form within the prothallium.
- The male antheridium produces haploid spermatozoids with flagellae.
- When it rains, a thin water film covers over the male antheridium and female archegonium.
- Chemotaxis occurs; the spermatozoid senses chemical cues given off by the female archegonium, to find it and swim inside of it.
- The spermatozoid swims inside the haploid egg; fertilizing it and producing a diploid zygote.
- Mitosis occurs; the zygote develops into an embryo.
- Mitosis continues; the embryo develops into a diploid sporophyte.
- Mitosis continues; a diploid frond sporophyte and a diploid root sporophyte begin to develop from the haploid prothallium gametophyte.
- After 2-3 weeks, the prothallium withers away. The diploid frond and root sporophyte have now fully developed into a mature leaf and root sporophyte.
macronutrient vs. micronutrient
macronutrients are required in large amounts, whereas micronutrients are required in small amounts
three photosynthetic pathways ranked from greatest to least water use efficiency (WUE)
CAM > C4 > C3
sinks
tissues that require carbon for energy or biosynthesis
- shoot or root meristems
- developing seeds
- developing flowers
- developing roots
features of parenchyma cells
- most common plant cell type
- alive; all organelles present
- thin-walled
- least specialized; cheapest cell to produce
- block-shaped
features of sclerenchyma cells
- dead at maturity; cell interior almost completely filled (organelles squished)
- cell walls thickened with cellulose and enforced with lignin
- expensive to produce
ideal C4 photosynthesis conditions
- arid, tropical habitats
- 30-45°C
suberized endodermal and root cells
older regions of root and the endodermis are enforced with suberin, making them impermeable to water
examples of C4 plants
- corn
- sugar cane
- sorghum
- millet
what flowers are
modified leaves
types of meristems needed for primary growth
both primary meristems (shoot apical meristem, root apical meristem) and secondary meristems (vascular cambium, ground meristem) are needed
types of micronutrients
- chlorine
- iron
- boron
- manganese
- sodium
- zinc
- copper
- nickel
- molybdenum
two types of spatial separation
“normal” spatial separation
- anthers (male) and stigma (female) are spatially separated, reducing the likelihood of within-flower selfing
spatial reciprocity (e.g. primrose flowers)
- some individuals have high anthers and short styles, whereas some have low anthers and long styles
- pollinators can only take pollen from one type of plant, to the other type of plant
where photosynthesis occurs in plants
parenchyma
varied self avoidance amongst the different sexual reproductive systems
- dioecious species cannot self
- monoecious and hermaphroditic species have mechanisms to avoid selfing
features of cork cells
- dead at maturity
- antimicrobial, wax-like walls with lignin and suberin; helps against desiccation
composition of the region of elongation in roots (outside to inside)
- protoderm
- ground meristem
- procambium
Chemical defense is often…
induced
Goldenrod is a… (generalist/specialist)
generalist
composition of (angiosperm) seed anatomy
- plant embryo, including the embryonic shoot, radicle, and cotyledons (embryonic leaves)
- testa (protective seed coat)
- endosperm (food for embryo)
- food for seed disperser
osmosis in roots
- ions are actively pumped into root hairs
- water moves from an area of low solute concentration (soil) to an area of high solute concentration (root cells) via the semipermeable membrane of the cell wall
total plant water transport explained with the three hypotheses on mechanisms of water transport
- Water enters through root hairs, and moves into xylem via osmosis and transpirational pull.
- Adhesion helps with the push of water, whereas cohesion helps holds together the string of water.
- Transpiration in leaves draws water from the roots up through the rest of the plant.
the number of cells in adult male Caenorhabditis elegans (C. elegans)
959 cells
function of root apical meristem (RAM), and what it’s protected by
- the primary meristem responsible for a plant’s underground growth (i.e. roots)
- protected by the root cap: renewable sacrificial cells that act as lube and grow through the gritty soil
Water moves between tracheids through…
pits
why the phosphorus cycle is geological
the source of phosphorus is bedrock
rule of thumb for (humus) soil
The darker, the better.
C3 plants’ major limitation
photorespiration, in dry conditions
- RuBisCo fixes O2, instead of CO2
- sugars break down into CO2 (net loss of previously bound sugars)
- occurs in 40% of C3 reactions
Water only flows in the newest ring of xylem because…
older xylem gets plugged
perennials
plants that live longer than a year
ideal C3 photosynthesis conditions
- moist habitats
- 16-30°C
basic plant needs
- glucose (from CO2, light, and water)
- water
- O2
- minerals and nutrients
most recent evolutionary group of plants
angiosperms
Water moves between vessel elements through…
perforations and pits
the main forces behind the evolution of flowers
- assurance of seed set: sheer mechanics, bringing female and male gametes together
- inbreeding avoidance: creating high-quality offspring and avoiding selfing
the percentage of plants that are wind-pollinated
10%
wood in the the summer vs. spring
Srping wood is bigger due to more water; xylem is larger and the plant grows more.
examples of plants with one carpel, one pistil, one ovary, and one ovule
- cherry
- peach
- apricot
- almond
- olive
these fruits have one seed
features and function of the cuticle
- the outermost, non-cellular waxy layer composed of fatty cutin (responsible for the waxy shine on grapes)
- aids in water loss and defense of the plant
- the thicker the cuticle, the less permeable to water and the more resistant to bacteria and pests
The life cycle of gymnosperms is almost identical to that of…
angiosperms
sources
tissues that make or dispense food
- endosperm
- photosynthetic leaves
- mature roots
temporal separation
- anthers (male) and stigma (female) are active at different times
- if only one flower per plant, very helpful for within-flower selfing
- if more than one flower per plant, not helpful as different flowers can be in different phases (within-individual asynchrony), leading to between-flowers selfing
examples of plants with three carpels, one pistil, three ovaries, and many ovules
- cucumber
- zucchini
these fruits have three fused ovaries
physical vs. chemical defense
- physical (mechanical) defense: tissues and organs
- chemical defense: plant toxins
the goal of photosynthesis
producing more sugar per transpired water
seven seed dispersal agents
- ballistochory: explosive self-dispersal
- anemochory: wind dispersal
- hydrochory: water dispersal
- exozoochory: external hitchhiking
- endozoochory: internal hitchhiking
- myrmecochory: ant dispersal
- barochory: gravity and secondary dispersal by small animals
the history of bees, and how they rely on flowers
- bees are the most important pollinators
- originated around 80 million years ago, and diversified with the evolutionary radiation of angiosperms
- adults feed on nectaries (secrete nectar) of 30-35% sugar
- larvae live on pollen, which is rich in protein
why the nitrogen cycle is biogenic
living organisms are needed to make atmospheric nitrogen (N2) bioaccessible
number of ATP used in the Calvin cycle
54 ATP
