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The Pollination Crisis (Unit 3)

Terms in this set (67)

a. Vascular tissue - cells joined into tubes that transport water and nutrients throughout the plant body

b. Xylem - conducts most water & minerals; tracheids - tube-shaped cells that carry water and minerals up from the roots; water-conducting cells of xylem dead at functional maturity and are lignified (cell walls strengthened by polymer lignin)
1. Lignified tissue provides structural support & longer spore dispersal

c. Phloem - cells arranged into tubes to distribute sugars, amino acids, and other organic products; alive at functional maturity

d. Life cycles with dominant sporophytes, but gametophytes still independent

e. Need water for fertilization and dispersal

f. Well-developed roots and leaves, including spore-bearing leaves called sporophylls

1. Sporophylls - modified leaves that bear sporangia
2. Homosporous - one type of sporophyll bearing one type of sporangium that produces one type of spore, which typically develops into a bisexual gametophyte (seedless vascular)
3. Heterosporophyll - megasporangia on megasporophylls produce megaspores (1) (female) and microsporangia on microsporophylls produce microspores (many) (male) (seed plants)

g. Roots - organs that absorb water and nutrients from the soil; anchor plants to ground, allowing shoot system to grow taller

h. Leaves - primary photosynthetic organ of vascular plants
1. Microphylls - small, often spine-shaped leaves supported by a single strand of vascular tissue
2. Megaphylls - larger leaves with a highly branched vascular system; greater photosynthetic
a. Seed - an embryo packaged with a supply of nutrients inside a protective coat; develop inside chambers that originate within flowers

b. Two integument layers

c. Gametophytes develop within flowers

d. Flowers - unique angiosperm structure specialized for sexual reproduction
1. Specialized shoot with up to four types of modified leaves (floral organs)
2. Sepals - sterile floral organ; usually green & enclose flower before it opens
3. Petals - sterile floral organ; usually bright & can aid in attracting pollinators
4. Stamens - microsporophylls that produce microspores that develop into pollen grains containing male gametophytes; consists of a stalk (filament) and terminal sac (anther) where pollen is produced
a. Male gametophyte has two haploid cells: generative (divides to form two sperm) and tube cell (produces pollen tube)
b. Penetrates micropyle & discharges two sperm (Double fertilization - one to fertilize egg to produce diploid zygote; one to fuse w two nuclei in large central cell to produce triploid cell)
5. Carpels - megasporophylls that produce megaspores that give rise to female gametophytes aka embryo sac; tip of carpal is sticky stigma that receives pollen; style leads from stigma to ovary which contains one or more ovules; if fertilized, ovule 🡪 seed
a. Pistil - a single/simple carpal or compound carpels
b. Micropyle - pore in the integuments of the ovule where the pollen tube penetrates
c. After double fertilization, ovule matures into seed, zygote 🡪 sporophyte embryo w rudimentary root & 1-2 seed leaves called cotyledons
d. Triploid develops into endosperms - tissue rich in starch and other food reserves that nourish developing embryo
6. Carpels & stamens may mature at different times or arranged so that self-pollination is unlikely
7. Vary in symmetry (radial/bilateral)

e. Fruits
1. As seeds develop from ovules after fertilization, ovary wall thickens and ovary matures into a fleshy or dry fruit
2. Protect seeds & aid in dispersal (wind, water, animals)

f. Insects transfer pollen from one flower to sex organs on another flower - most more directed than wind-dependent pollination of most gymnosperms
a. Flowers - unique angiosperm structure specialized for sexual reproduction
1. Specialized shoot with up to four types of modified leaves (floral organs)
2. Sepals - sterile floral organ; usually green & enclose flower before it opens
3. Petals - sterile floral organ; usually bright & can aid in attracting pollinators
4. Stamens - microsporophylls that produce microspores that develop into pollen grains containing male gametophytes; consists of a stalk (filament) and terminal sac (anther) where pollen is produced
-Male gametophyte has two haploid cells: generative (divides to form two sperm) and tube cell (produces pollen tube)
-Penetrates micropyle & discharges two sperm (Double fertilization - one to fertilize egg to produce diploid zygote; one to fuse w two nuclei in large central cell to produce triploid cell)
5. Carpels - megasporophylls that produce megaspores that give rise to female gametophytes aka embryo sac; tip of carpal is sticky stigma that receives pollen; style leads from stigma to ovary which contains one or more ovules; if fertilized, ovule 🡪 seed
-Pistil - a single/simple carpal or compound carpels
-Micropyle - pore in the integuments of the ovule where the pollen tube penetrates
-After double fertilization, ovule matures into seed, zygote 🡪 sporophyte embryo w rudimentary root & 1-2 seed leaves called cotyledons
-Triploid develops into endosperms - tissue rich in starch and other food reserves that nourish developing embryo
6. Carpels & stamens may mature at different times or arranged so that self-pollination is unlikely
7. Vary in symmetry (radial/bilateral)

b. Fruits:
1. As seeds develop from ovules after fertilization, ovary wall thickens and ovary matures into a fleshy or dry fruit
2. Protect seeds & aid in dispersal (wind, water, animals)

c. Insects transfer pollen from one flower to sex organs on another flower - most more directed than wind-dependent pollination of most gymnosperms
a. Multicellular, heterotrophic eukaryotes with tissues that develop from embryonic layers

b. Multicellular w cell specialization

c. Feed by ingesting food and then using enzymes to digest it within bodies

d. Proteins external to cell membrane provide structural support & connectivity (collagen)

e. Cells of most animals are organized into tissues, groups of similar cells that act as a functional unit

f. Most reproduce sexually & diploid stage dominates life cycle; small, flagellated sperm fertilizes a larger, nonmotile egg, forming a diploid zygote

g. Zygote then undergoes cleavage - mitotic cell divisions without cell growth b/w divisions that lead s to blastula - multicellular embryonic stage resembling a hollow ball

h. Blastula develops into gastrula during gastrulation, during which layers of embryonic tissues that will develop into body parts are produced

i. Most animals have larval stage; larva - sexually immature form of animal that is morphologically distinct from adult, eats different food, and may have a different habitat; larva eventually undergo metamorphosis - developmental transformation that turns larva into juvenile (resembles adult but is sexually immature)

j. Most contain Hox genes - unique family of homeobox-containing DNA sequences; play important role in development of embryos & control expression of many other genes influencing morphology

k. Choanoflagellates - protist, closest living relative of animals
1. Origin of multicellularity requires the evolution of new ways for cells to adhere and signal to each other; involved new ways of using proteins encoded by genes found in choanoflagellates

l. Body plan - a particular set of morphological and developmental traits that are integrated into a functional whole
1. Symmetry (none, radial, bilateral)
-Deuterostomia (bilaterian clade) - hemichordates, echinoderms, chordates
-Lophotrochozoa (bilaterian clade) - platyhelminthes, syndermata, ectoprocta, brachiopoda, Mollusca, anneledia
-Ecdysozoa (bilateral clade) - nematoda, arthropoda
2. Tissue organization (gastrulation)
-ectoderm (surface of embryo), endoderm (innermost layer), mesoderm (in between)
-diploblastic, triploblastic
3. body cavity - fluid or air-filled space located between the digestive tract (endoderm) and outer body wall (ectoderm); provide structural support, facilitate internal transport of nutrients, gases, and wastes
-coelom - body cavity that forms from tissue derived from mesoderm; fluid cushions suspended organs to prevent internal injury
-hemocoel - body cavity that forms between mesoderm and endoderm; contains hemolymph, a fluid which functions in the internal transport of nutrients and waste
-acoelomates - no body cavity; flat, few cells thick, exchange of nutrients, gases, wastes can occur across entire body surface

m. Protostome and deuterostome development
1. Protostome development
-Spiral cleavage - planes of cell division are diagonal to vertical axis of embryo; determinate cleavage - rigidly casts the developmental date of each embryonic cell very early
-Coelom forms from splits in mesoderm
-Blastopore - indentation during gastrulation that leads to the formation of the archenteron; blastopore forms mouth
2. Deuterostome development
-Radial cleavage - cleavage planes parallel or perpendicular to the vertical axis of the embryo; indeterminate cleavage - each cell produced by early cleavage retains capacity to develop into a complete embryo
-Coelom forms from mesodermal outpocketings of the archenteron (developing digestive tube that initially forms as a blind pouch)
-Blastopore - indentation during gastrulation that leads to the formation of the archenteron; blastopore forms anus
Corals, jellies, and hydras

Key (Chart): Diploblastic, radially symmetrical; incomplete gastrovascular cavity (mouth and anus single opening); acoelomate; no segmentation

Key (Traits): Cnidocytes for prey capture; dimorphism with alternate generations in life cycle (polyp & medusa)

Sessile polyp - cylindrical forms that adhere to the substrate by the aboral end of their body (opposite mouth) and extend tentacles, waiting for prey

Motile medusa - resembles flattened, mouth-down version of polyp that moves freely through water by passive drifting & contractions of bell-shaped body

Predators that often use tentacles arranged in ring around mouth to capture prey & push food into gastrovascular cavity

Cnidocytes - cells unique to cnidarians that function in defense and prey capture on tentacles

Contain cnidae - capsule-like organisms capable of exploding outward
1. Nematocysts - specialized cnidae that contain a stinging thread that can penetrate the body surface of prey

Cells of epidermis and gastrodermis have bundles of microfilaments arranged into contractile fibers that work against gastrovascular cavity to move

No brain; noncentralized nerve net is associated with sensory structures distributed around body; can detect & respond to stimuli from all directions

Two major clades - Medusozoans & Anthozoa

1. Medusozoans - produce a medusa (jellies, box jellies, hydrozoans - alternate bw medusa & polyp except for hydras' polyp)
2. Anthozoans - occur only as polyps (sea anemones & corals); secrete a hard exoskeleton of calcium carbonate
Key (Chart): Triploblastic, complete digestive tract; coelomate; bilateral symmetry; no segmentation

Key (Traits): foot, mantle, visceral mass, radula for feeding; external shell

Snails, slugs, oysters, clams, squids, and octopi (second most diverse phylum after arthropods)

Mostly marine, some freshwater & terrestrial

Soft body, usually secrete hard shell of calcium carbonate

Primary body cavity is hemocoel but also have reduced coelom

Many have open circulatory system

Muscular foot used for movement; visceral mass contains most internal organs inc gonads (ovaries/testes); mantle is fold of tissue that drapes over visceral mass and secretes shell (if present)

Mantle often extends beyond visceral mass to produce mantle cavity (water-filled chamber) w gills, anus, and excretory pores

Radula - straplike organ to scrape up food & feed

Most have separate sexes but many snails hermaphrodites

Marine molluscs have ciliated larval stage - trochophore (also present in marine annelids & some other lophotrochozoans)

Eight major clades, inc:
1. Polyplacophora (chitons)
-Unsegmented oval-shaped body & shell w eight dorsal plates
2. Gastropoda (snails & slugs)
-Mostly marine
-Move by rippling motion of foot or by cilia (slow)
-Single, spiraled shell to retreat into
3. Bivalvia (clams, oysters, mussels, scallops)
-Shell divided into two hinged halves w adductor muscle drawing them together tightly
-No distinct head, lost radula
-Gills used for feeding & gas exchange
-Most suspension feeders & sedentary
4. Cephalopoda (squids, octopi, cuttlefishes, chambered nautiluses)
-Marine predators that use tentacles to grasp prey & then bite w beak-like jaws & immobilize w poison saliva
-Foot modified into muscular excurrent siphon and part of tentacles
-Shell generally reduced and internal or missing
-Only molluscs w closed circulatory system (blood separate from fluid in body cavity)
-Well-developed sense organs & complex brains
Key (Chart): Triploblastic, complete digestive tract; coelomate; bilateral symmetry; segmentation

Key (Traits): joined appendages, exoskeleton; molting

Ecdysozoan
Vast majority of known species (insects, crustaceans, arachnids)

Specialized segments - driven by changes in sequence or regulation of existing Hox genes

Excrete & molt exoskeletons (cuticle); ecdysis - molting; exoskeleton made of protein & polysaccharide chitin layers; protection, water conservation, support

Jointed & paired appendages
Well-developed sensory organs (eyes, olfactory receptors, antennae for touch & smell) concentrated at anterior

Open circulatory system - hemolymph propelled by heart through short arteries into hemocoel

Specialized gas exchange organs allow diffusion of respiratory gases despite exoskeleton

Three major lineages: chelicerates, myriapods, pancrustaceans
1. Chelicerates (sea spiders, horseshoe crabs, scorpions, ticks, mites, spiders)
-Chelicerae - clawlike feeding appendages
-Lack antennae, simple eyes
-Arachnids (scorpions, spiders, ticks (bloodsucking parasite on amniotes), mites) - six pairs of appendages
2. Myriapods (centipedes, millipedes)
-Terrestrial
-Antennae & three appendage pairs modified as mouthparts
-Millipedes - each segment formed from two fused segments w two leg pairs; eat leaves and decaying plant matter
-Centipedes - each segment has one leg pair; carnivores
3. Pancrustaceans (insects, lobsters, shrimp, barnacles)
-Crustaceans
^Marine, freshwater, terrestrial
^Only arthropods w two antennae pairs
^Have appendages on post-genital region
^Separate sexes
^Isopods - one of largest groups
^Decapods - lobsters, crayfishes, crabs, shrimps; cuticle hardened by calcium carbonate
^Barnacles - sessile, cuticle hardened into shell w calcium carbonate, anchor selves to submerged surfaces w natural adhesive
-Insects (hexapoda)
^Many have 1-2 wing pairs on dorsal side of thorax that are extensions of cuticle
^Many undergo either complete or incomplete metamorphosis
^Reproduction typically sexual w separate males/females & internal fertilization
Key (Chart): Triploblastic, complete digestive tract; coelomate; radial symmetry; no segmentation

Key (Traits): water vascular system with tube feet; secondary pentamerous radial symmetry

Deuterostome development - radial cleavage and formation of anus from blastopore

Slow-moving or sessile marine, have a coelom, thin epidermis covers endoskeleton of hard calcareous plates, prickly from skeletal bumps & spines

Water vascular system - network of hydraulic canals branching into extensions called tube feet that function in locomotion and feeding

Sexual reproduction - separate male/female that release gametes into water

Appear to have radial symmetry but larvae have bilateral symmetry, and adults not truly radial

Five clades:
1. Asteroidea: sea stars & sea daisies
-Sea stars have arms radiating from central disk w tube feet under arms that attach/detach to/from substrate through muscular & chemical action & grasp prey
-Sea stars invert stomach for digestion & can regenerate
-Sea daisies disk-shaped, absorb nutrients through membrane surrounding body
2. Ophiuroidea: brittle stars
-Distinct central disk & long, flexible arms
-Suspension feeders, predators, scavengers
3. Echinoidea: sea urchins & sand dollars
-No arms, five radially arranged groups of tube feet that function in slow movement
-Sea urchins - spherical, muscles for locomotion, jaw-like structures
4. Crinoidea: sea lilies & feather stars
-Sea lilies attach to substrate by stalk; feather stars crawl w long, arms
-Suspension feeders - arms encircle mouth that is directed upward
5. Holothuridea: sea cucumbers
-Lack spines, reduced endoskeleton, elongated in oral-aboral axis
-Five radially arranged sections of tube feet, including around mouth as feeding tentacles
1. Principle characteristics:
a. Notochord - longitudinal, flexible rod located between the digestive tube and the nerve cord
-skeletal structure present in all embryos and some adults
-composed of large, fluid-filled cells encased in fairly stiff, fibrous tissue
-provides skeletal support & firm, flexible structure for muscles to work against
-in most vertebrates, more complex jointed skeleton develops around ancestral notochord; adults have only remnants of embryonic notochord
b. Dorsal, hollow nerve chord - develops from a plate of ectoderm that rolls into a neural tube located dorsal to the notochord
-Other phyla have solid nerve cords usually ventrally located
-Develops into central nervous system (brain & spinal cord)
c. Pharyngeal slits/clefts - Series of arches separated by grooves forms along outer surface of pharynx, grooves (clefts) develop into slits that open to pharynx
-Pharynx - region just posterior to mouth
-Allow water entering mouth to exit body w/o passing through entire digestive tract
-Function as suspension-feeding devices in many invertebrate chordates
-Aka gills in non-tetrapod vertebrates
-In tetrapods, develop into parts of ear and other structures instead of slits
d. Muscular, post-anal tail
-Tail that extends posterior to anus; greatly reduced during embryonic stage for many
-Most non-chordates have digestive tract extending nearly entire length of body

2. Cephalochordata (lancelets)
a. Sister group to other chordates
b. As larvae, develop notochord; dorsal, hollow nerve cord, numerous pharyngeal slits, and post-anal tail | retain traits as adult
c. Serial arrangement of muscles (segments) develop from blocks of mesoderm called somites, which are found along side of notochord in all chordate embryos

3. Urochordata (tunicates)
a. Chordate characters most apparent during larval stage
b. Once it settles on substrate, undergoes metamorphosis in which many of its chordate characteristics disappear (tail & notochord reabsorbed, nervous system degenerates, remaining organs rotate 90 degrees)
c. Adults draw in water through incurrent siphon, water passes through pharyngeal slits into atrium chamber & then exits through excurrent siphon
d. Adults - food particles filtered by mucus net & transported by cilia to esophagus; anus empties into excurrent siphon
e. Loss of four Hox genes as compared to other chordates

4. Vertebrata -
a. Skeletal system & more complex nervous system - more efficient at capturing food & avoiding being eaten
b. Possess two or more sets of Hox genes
c. Development of skull and backbone composed of vertebrae that usually enclose spinal cord
d. Neural crest - collection of cells that appears along the edges of the closing neural tube of an embryo; cells disperse throughout embryo & give rise to many structures (teeth, cartilage, neurons, sensory capsules for sense organs, etc)
e. Hagfishes and lampreys
-Sister groups
-only living vertebrate lineages w/o jaws or backbone (the cyclostomes, not gnathostomes)
-have rudimentary vertebrae composed of cartilage (hagfishes have cartilage skull)
-hagfishes - segmental muscles to swim; tooth-like formations made of protein keratin; marine scavengers
-lampreys - marine & freshwater, some parasites; cartilage skeleton w no collagen (most vertebrates contain collagen in cartilage)
f. bony skeleton emerged after cartilage skeleton (mineralized)
Gnasthostomes - jawed vertebrates (sharks & relatives, ray-finned fishes, lobe-finned fishes, amphibians, reptiles, mammals)

Jaws - hinged structures that (esp w teeth) enable them to grip food items firmly and slice them

Jaws evolved by modification of the skeletal rods that had previously supported the anterior pharyngeal (gill) slits (remaining slits remained as major sites of respiratory gas exchange w external environment)

Additional duplication of Hox genes (entire genome duplicated)

Forebrain enlarged compared to other vertebrates - associated w enhanced smell & vision

Lateral line system - organs form a row along each side of body and are sensitive to vibrations in surrounding water

Chondrichthyans (sharks, rays, & relatives)
a. "Cartilage fish" - skeleton composed mostly of cartilage (& often calcium)
b. Mineralization of skeleton began before divergence, bone traces now in teeth bases & scales, so restricted bone distribution is derived
c. Sharks - streamlined body, swift swimmers, do not maneuver well, continuous swimming ensures not sinking & water flow into mouth/out gills for gas exchange
d. Largest sharks & rays suspension feeders that consume plankton, but most sharks carnivorous
e. Sharks have spiral valve in intestine to increase SA & prolong food passage
f. Sharks have sharp vision but no color, can detect electric fields of nearly muscle contractions, no eardrums - entire body transmits sound
g. Sharks - internal fertilization
h. Rays bottom dwellers, crush molluscs/crustaceans, flat shape & enlarged pectoral fins, whiplike tail

Osteichthyans (ray-finned fishes & lobe-fins)
a. Nearly all have ossified (bony) endoskeleton w hard matrix of calcium & phosphate
b. Most breathe by drawing water over 4-5 gill pairs located in chambers covered by operculum (protective bony flap)
c. Maintain buoyancy equal to surroundings by filling swim bladder (air sac that arose from lungs)
d. Skin covered by flattened, bony scales
e. Glands secrete slimy mucus over skin to reduce drag in swimming
f. Lateral line system
g. Mostly external fertilization
h. Ray-finned fishes - bony rays support fins
i. Lobe-fins - rod-shaped bones surrounded by thick muscle layer in pectoral & pelvic fins (coelacanths, lungfishes); tetrapods evolved from third surviving lineage
1. The sources and destination of the water and salts entering the nephron
-Filtrate formed when blood pressure forces fluid from blood from afferent arteriole (offshoot of renal artery) of glomerulus into lumen of Bowman's capsule
-Capillaries and capsule permeable to water and small solutes (salts, glucose, amino acids, vitamins, nitrogenous wastes, etc.; not proteins & blood cells)
-Capillaries converge as leave glomerulus to form efferent arteriole which forms peritubular capillaries that surround proximal and distal tubules & the vasa recta (hairpin-shaped capillaries that serve renal medulla, inc Loop of Henle of juxtamedullary nephrons)
-Filtrate processed in proximal tubule (salt active, water osmosis), loop of Henle (water passive through aquaporins, salt passive active), and distal tubule (water osmosis, salt active); most water, sugars, amino acids, vitamins & other organic nutrients reabsorbed into blood
-Collecting duct (urea and water passive out) receives processed filtrate from many nephrons and transports it to renal pelvis

2. How the fluid in the loop becomes concentrated
-Filtrate processed in proximal tubule (salt active out, water osmosis out, HCO3 passive out, K+ passive out, H+ active in, ammonia passive in)
-Loop of Henle (water passive through aquaporins, salt passive & active out)
-Distal tubule (water osmosis out, salt active out, HCO3 active out, K+ active in, H+ active in)
-Collecting duct (urea passive out, water osmosis out, salt active out)

3. How changes in permeability control the movements of salt and water
-Descending loop - permeable to water but not salt and vice versa for ascending

4. How active and passive transport play their roles in the movement of water and salts
-When salt removed actively or passively, water follows by osmosis.

5. What gradients are established, and how and why they are established.
-concentrations of solutes in inner medulla due to countercurrent multiplier systems; also the active transport of NaCl in ascending loop of Henle
-Urine hyperosmotic to blood and interstitial fluid elsewhere in body, thereby conserving water

6. What the effect of increasing the loop is
-Juxtamedullary nephrons enable the shedding of salt and nitrogenous wastes without losing water