Chemistry Research Essay, Research Paper CHAPTER 32 The tallest tree is the Redwood (Sequoia sempervirens) approx 110 m The tallest Angiosperm is the Australian Eucalyptus regnans
Chemistry Research Essay, Research Paper
The tallest tree is the Redwood (Sequoia sempervirens) approx 110 m
The tallest Angiosperm is the Australian Eucalyptus regnans
Water Uptake and transport (Fig. 32.1)
= water is essential because: transport solute, cool the body, photosynthesis and Turgor pressure
Osmosis- movement of H2) through a semi-impermeable membrane
Osmotic potential ( o)-depend on dissolve solute: Hi concentration means more negative o.
Isoosmotic-two solution with same o; Hypoosmotic- solution that has a less negative o(more +)
Turgor Pressure -hydraulic pressure result from water up take, cell turgid; analog to air pressure in a tire
Water Potential ( )-Overall tendency of a solution or cell to take up water from pure water solution.
= o + P, P is positive and is measured in MegaPascal (MPa); loss in P means the plant will wilt.
= Mineral and ions transported across membranes by protein: Pumps and Ion channel & Symport
= Use both Facilitated (low K outside cell) and Active transport (depend on Respiration).
= Plant do not have a Na/K pump but a H pump (generate membrane potential/ gradient).
= Ion transport changes Electric potential of membrane (-120mV- can be measure by electrodes)
= The traffic of ions into/out of cell can be measure by Patch clamping technique.
Apoplast & Symplast
= Water moves into the Stele (more – ) from the cortex (less – ) from the soil (more less – )
= Mineral move by Mass flow or diffusion/Active transport (via Membrane Protein)
Apoplast-movement through cell wall and intercellular space; it is continuous
Symplast- movement through the cell and b/w cell via plasmodesmata; continuous but regulated
= H2O from the Apoplast stops at the Endodermis (Stele); have Casparian strips -made of suberin
= Strip separate Apoplast of the cortex from the Apoplast of the stele (periclcle)
= Membrane protein enable enables selective mineral uptake and uptake rate.
Transfer cells -in pericycle, transport minerals from cytoplasm back into the apoplast (MP/Mit, SA, rate)
TRANSPORT IN XYLEM
Model 1-”pumping cells” stem; ruled out by Eduard Strasburger exp-use poison pitric acid; Stop in the leaf
= Exp. demonstrate: (1) pumping cell not responsible for uptake (2) leaves important (3) root not involve
Model 2- “Capillary action” ruled out because capillary action cannot support 110 m tree (40 cm)
Model 3- ” root pressure”-based on more – in xylem & less neg in root; support by guttation
Guttation- the removal of H2O through the leaves under high humidity and a abundance of H2O in the soil
= The Oozing of sap from a cut stem of Coleus when the top is remove; not enough
= Root pressure changes, it either weaker or stronger but will not exceed 2X atm pressure
Evaporation-Cohesion-Tension mechanism (Fig. 32.8)
(1)Evaporation of H2O through stomata-increase tension &make wall more – o; H2O enter nearest vein
(2) Removal of H2O from leaf cause pull of water below; pull is send through the whole column
(3) Column is maintain by the adhesion of water to the cell wall (glass)
Summary-evaporation account for xylem transport & the resulting tension cause the cohesion
Dry Air-more – o than root–less neg than sap in xylem which is less neg in leaf–less than air
= Minerals dissolve in sap is transported to rest of the plant body by the phloem
Evaporation-Cohesion-Tension mechanism -requires tension in column or solution of the xylem
= Pressure can be measure by pressure bomb; done by Per Scholander, Fig 32.9
= In vines there is no tension in xylem until the leaves are removed; some Plants loss tension at night
TRANSPIRATION THROUGH THE STOMATA
Transpiration- is the loss of water from shoot (leaf) by evaporation; also cools the cell
= Loss is minimize by the cuticle; impermeable to CO2
Stoma- composed of specialized guard cells in the epidermis which allow passage of H2O/CO2
= In monocot it is associated with specialized epidermal cells; but mechanism is the same in dicot
= Open by pumping of K into guard cells; stretching is regulated by Microfibril
= Pumping also allow for Cl & other organic ion uptake; maintain electrical balance or neutrality
= Increase CO2 level in spaces of leaf and – (release of ABA); blue light also reduce H pumping
CAM-succulent plants-Crassulaceae-such as Kalonchoe
= Have a backward stomata cycle- opens at night; leaf tissue becomes acidic (Malic/Aspartic acid
= Adapted for environment devoid of water; loss of H2O occurs in cool environment.
= Occur in the Phloem- transport sugars, aa, minerals from leaf to root
Model: bi-directional, up and down the stem or petioles (2) Arrest if tissue is damage by heating
(3) Inhibited by compound that inhibit cellular respiration
Pressure Flow Model- fig. 32.14-32.16
= Involve active transport of sugar into sieve tube at source (leaf) and removal at sink (stem/root)
= Sieve tubes at source cause increase in Turgor pressure; fluid is squeeze toward the Sink ends
Sieve Plates- must be unclogged: it is regulated by protein which is randomly distributed (until cut)
= Sugars pass from cell to cell via symport, then into the apoplast (active); likewise into sieve tube
= Apoplast selectively sort out which compound is to be translocated; Sym-Apo-Sym not universal
= Sucrose is transported via secondary transport through a symport protein (H/Sugar protein)
= In sink sugar are actively unloaded-maintain gradient and P in tube; Also build up sugar in seed/fruits
= In some plants, Maple, sugar is stored as starch in xylem(living) of trunk/twigs; digested in spring (syrup)
Need of one versus the many
Sponges- compose of group of cell in direct contact w/ environment; function independently
= get nutrients from seawater; only two layers thick
Multi-cellular organism- creates internal environment made of varying extracellular matrix
= Cell meet need & exchange w/ internal environment (IE)function independently thereof
= Allow animal to occupy various habitat; Cell become specialized and efficient due to constant internal envment
= Cell become arrange in tissue system which maintain internal Environment & perform certain task
= Evolution of animal physiology maintain progress of cell-tissue-organs-organ system-maintain IE.
HOMEOSTASIS- maintenance of a constant composition of the IE-regardless of it continual/variable.
= Enable organism to function and adapt; It is under control and regulation in response to IE/EE.
= Control and regulation requires information-Endocrine and Nervous system.
Organ & organ system- many types
Organ- group of tissue compose of cell with similar structure and biological function; 4 cell types
= Epithelial, connective, muscles and nervous
Epithelial-sheet of cell of intestine, skin and lungs; some have secretory function
= mucous, digestive enzymes and sweat; some are ciliated- Olfactory system and fallopian tubes
= some involve in absorption and transport; some are stratified (skin) or single layered-GUT
Connective tissue- support and to reinforce other tissue .
= Cell are embedded in extracellular matrix; Include ligament and tendons; lens of the eye; surround Gut
= Include the Skin contain elastrin protein but degrades with age; Bones-is a dense connective tissue
= Include Adipose tissue- fat cells and the Component of blood
Muscle tissue- include cells that cause movement of organs and limb; 3 types
Skeletal-connects bone to bone; under Somatic NS control-responsible for behavior.
Smooth muscles- found in internal organ (stomach); involve in the constriction of blood vessel
Cardiac muscles -make up heart and pump blood
Nervous tissue -enable animal to deal w/info; 2 basic cell type
Neurons-generate electrochemical signals; response to specific stimuli;
= Communicate over long distances with other neurons/muscles/secretory cell; control activity of most organ
Glial cell -support function of neurons; abundant in brain
NERVOUS AND ENDOCRINE SYSTEM
Nervous-process info and use the info to control physiology and behavior
= Brain, Spinal cord and peripheral nerves-conduct signal from sensor to CNS; CNS to effector
= Sensors- eye, ears, organ of taste and smell, organ of balance and orientation, touch; pain/temp/Pressure
Endocrine system -process info and control function of organs via extracellular fluid (hormones)
= Ductless glands-secretes hormone in blood; pancreas secretes insulin
= There is a close interaction b/w NS and ES; cell in brain produce hormone that effect ES and vice versa
= Messenger of ES or Endocrine Glands travels great distance to stimulate target cells
SKIN, SKELETON AND MUSCLE SYSTEM
Skin- the 1st line of defense against pathogens, loss of water; It’s the largest organ
= It a major sense organs-control rate of heat exchange (neurons); regulate body temperature.
Skeleton system -support and protection; also an effector ; support lever system for movement.
Muscle system -include muscles under conscious (skeletal) & unconscious control & cardiac muscles
Gonads- male/female reproductive organs; include the testes/ovaries; they produce gametes
= include organ that deliver the organs; uterus-support the embryo
= Mammary glands-provides nutrient for infants(breast); Gonads- contain hormone producing tissues.
DIGESTIVE SYSTEM -extend from mouth to anus.
= It’s a continuous tubular structure–include the Gut; Gut is divided in different segment so differ function
= Involve in digestion of food and absorption of nutrients; Glands-deliver digestive enzyme to the Gut
= The lower Gut (intestine) reabsorb H2O from waste; Stores waste and eliminate them.
GAS EXCHANGE SYSTEM -Trachea, Larynx, diaphragm
= Also called respiratory system–provide O2 and eliminate CO2
= Lung- consist of many airways leading to membranous sac with large SA; the alveoli
= Diaphragm? is a muscle and delivers air into and out of lungs
= Transport O2 from lungs to rest of body and CO2 from tissue to the lungs
= Transport nutrients from gut, deliver waste (N2 ) to excretory system; regulate by hormones & remove heat
Blood? contain a liquid medium the Plasma-is continuous with the extracellular fluids
= Consist of vesicles extending through the body; do not include the heart and is not a circulatory system
= Provide the extracellular fluid to circulatory system; include the immune system
= Contain specialized blood cell produce in the spleen, lymphatic nodes, thymus and bone marrow
Urine-contain salt and waste product from catabolism of Amino acids and NA
= Include the Kidney-control water content of body and correct salt composition of extracellular fluid
=Bladder- storage of urine; Ureter- tube b/w kidney & bladder; Urethra-opening that release urine;
= Skin- excrete H2O and salt. Excretory system: also include the end of the digestive tract
CONTROL OF REGULATION
Homeostasis- depend on control/regulation of organs; organ system- depend on the need of cell of body
Control-implies change in rate of a process; Regulation-a physiological concept-refer to maintain to a certain limit
Regulation- requires the ability to obtain and use information.
= Physiological regulation requires feedback from control system
= AND how the information is obtain, process, integrate & converted by the regulatory system.
To analyze a regulatory system requires US to identify the source of feedback.
Thermostat-heating-cooling system is a regulatory system; furnace/ air condition is the control system
Sensors- provide the negative feedback; positive feedback amplifies an already existing response (ethylene)
Feed forward information- changes the set point; it adds a clock
TEMPERATURE AND LIFE
= All living cell function between – 0 C and 45 C;
= Chemical reaction are temperature sensitive; measure in terms of Q10 =RT/ RT-10;Q10 =1 not sensitive
= Q10 can be measure for single reaction or complex physiological process (O2 consumption)
= Biological process is between 2 to 3; Temperature change can be detrimental to animal
= Some animal BT is coupled to it external temperature.
Acclimalization- a physiological& biological change that animal undergo in response to seasonal change in climate
= Fish-temp difference is always higher if remove from pond to lab and then to pond
Metabolic compensation-readjustment of biochemical mechanism to counter effect of temp due to Acclimalization
= It is not sensitive to seasonal changes but to short term fluctuation (lysozymes-diff temp same function)
MAINTAINING OPTIMAL BT
Homeotherms-animal that regulates Bt at constant levels
Poikiltherms-animals whose temperature changes
Heterotherms-Animal that regulates it’s BT at constant level some of the time
Ectotherms-depend on external source of heat to maintain BT above ET
Endotherms-regulate BT by producing heat metabolically or by metabolizing active mechanism of heat loss
ENDODERMS VS ECTODERMS
= Ectoderms cannot regulates it BT independently of it environment; BT will not drop below ambient temp
= Endotherms regulates it Bt by altering it’s rate of metabolic heat loss
= Endotherms also have behavioral themoregulation; Ex. Nest construction/huddling; widespread in Animals
= Both can alter their rate of heat exchange b/w blood and environment-control the flow of blood to skin
Ex, Iguana of Galopagus- control BT by blood flow to skin; slower heart rate; these are adaptive process.
= Some Ectoderms must maintain a certain temp at specific parts of it body (flight muscle, beetles, honeybee, shark)
THERMOREGUALTION IN ENDOTHERMS -Fig 37.13b, 37.14
Thermoneutral zone -narrow range of temp in which metabolic rate of Endotherms is temp independent
Basal metabolic rate- is temp of metabolic rate of an animal resting in a thermoneutral zone ( no digestion/reprod)
= 6X the rate of an Ectotherms of same size; Endotherms have “leaker cells-expend E for Na/K-increase rate
Low zone-high rate to maintain BT due to heat loss; At maximum rate BT decline (dies).
At high extreme-expand heat to cool the body (pants/sweat); at maximum rate/High temp- BT increases (dies)
Methods- mammals-either shiver or sweat; birds-shiver (skeletal muscle ATP–heat)
= Brown fats–Non-shivering; use tissue rich in Mit/blood supply and Thermogenin.
COLD vs HOT- Fig. 37.21
THERMAL INSULATION AND RATE OF HEAT LOSS
= Thermal energy is release by body to it’s environment
= Muscle contraction or change blood flow to skin; WOLF-constrict Blood vessel in its feet at above 0 C
= Elephant, Rhinos, water Buffaloes have thick layer of fur; so they wallow in water
= Sweating, panting are last resort use bu animals in hot climate or habitat (H2O evaporate quickly)
THE VERTEBRATE THERMOSTAT- Fig 37.22/37.23
= All animals that thermoregulate must have a regulatory system; Info get from Hypothalamus-integration center
In Humans: If glands is cool BT rises (constriction of Blood vessels and increase rate); Hypo temp is – feedback
= Amount of increase in heat is proportional to how much the glands is cooled below the Set point.
= Hypothalamus receive info from sensor in skin to shift the set point for responses; Higher when skin is cold
Fever is a rise in BT in response to substance called Pyrogens; heat production above set point cause chills, shiver
= Macrophages attack antigen then secretes interleukins; Interleukin stimulate prostaglandin and raise the set point
ANIMAL AND THEIR THERMOSTAT
Hypothermia- condition in which BT is below normal (starvation, illness, anesthetic)
= Can cause unconsciousness, weaker contraction, nerve impulse, slow metabolism, cell damage/O2)
Torpor-condition in which an animal lowers its BT during the time of inactivity (Air temp, mice, hummingbird)
= Willow tit lowers it Bt at night; the brain of the willow is it’s integrated center for the thermostat.
Hibernation -is the hyptherming to low temp for days of weeks;
= It assures maximum energy conservation; BT is maintain at freezing pt.
= Metabolic rate 1/5 basal (Ex bats, bears, squirrel, poor will); occur when temp is low and food scarce
= Control by biological clock(Circannual rhythm); rhythm cycle of squirrel include active season; Hib-spring to fall
Active season -Animal breed, raise young, prepare nest, fatten bodies and store food
Hibernation season -occur in bouts; lose body weight; at end sex organs become functional
MUSCLE CONTRACTION: Actin/myosin interaction
Effectors-adaptation in response to info that is sensed, integrated & transmitted by its neuron & endocrine
= Muscle contraction is the most important effector mechanism in animal in response to Environment cues
= All physiological and behavioral response depend on muscle cells
Muscle Cells- have high density microfilament and myosin
= Account for movement in earthworm, jelly fish, limb movement in Anthropods/vertebrates
= Found in blood vessel, gut, bladder and heart or where ever tissue contracts
= Smooth, Skeleton and Cardiac
= Provides contraction for internal organs under control of autonomic Nervous System (involuntary control)
= Move food through digestive tracts; involve in blood flow and empties the urinary bladder
= Simpliest cell- long spindle-shaped w/single nuclei; actin/myosin not regularly arrange
In digestive tracts: arrange as sheet of attach by Gap junction (electrical conduction)
= Stretching the tract depolarize it’s membrane potential- result in contraction; longer contract more stretch
SKETETAL MUSCLES -straited muscle
= Control all voluntary movement: running, playing the piano, generate movement of breathing
= Highly regular arrangement of Actin/myosin; Muscle fiber are large & multi-nucleated
= Biceps compose of muscle fibers bundled together by connective tissues (Fig. 44.1)
Muscle fibers- compose of myofibrils
Myofibrils- are bundles of contractile filament; each thick filament is surrounded by thin filament
= Band pattern of myofibril due to its repeated units called Sarcomeres-the unit of contraction.
= The I-band- the region b/w A-bands and the Z-line ; contain only thin filament (light)
= A-band region of thick filament (center); H-zone- M-line and region where thick/thin do not overlap
= Sliding of Filament theory-propose by Andrew and Hugh Huxley
= Shorten of the H-zone and I-band; Z-line moves towards the A-band as if Actin is slide over myosin
MYOSIN- made of 2 polypeptide chain coils ending in a globular head (contain ATPase)
= Myosin filament compose of myosin molecules arranged parallel w/the head protruding
MICOFILAMENT- consist of helically arranged polypeptide chain consisting of G-actin globular protein
= Contain tropomyosin (2 chain) twist around Actin helix & Troponin- binds Ca, Actin, Tropomyosin
= Head of myosin filament interact w/Actin cause 5-10 nm shift relative to the other; ATP return the system
Rigor mortis -stiffness on muscle after death; no ATP no release of filament
= Muscle at different part of body soften at different times (lose integrity); estimate time of death
Interaction and Calcium
Motor Unit- all fibers innervated by a single motor neuron which triggers it to contract
(1) Contraction is initiated by nerve impulses at neuromuscular junction; receptor binding of molecules
(2) Molecules is release in the synapsis by neurons via action potential (open channel) along it
(3) Polarization of Plasma membrane of fibers send message throughout fibers & T-tubule system
(4) Ca is pump into Sarcoplasmic Recticulum (SR) from Sarcoplasm (contact with T-tubule system)
(5) Hi conc of Ca in SR is release into Sarcoplasm by opening of channels via the action potential
(6) Binding of Ca to Troponin induce change in Tropomyosin which expose Actin-myosin bind site
SMOOTH MUSCLE CONTRACTION
= Contain no Troponin-Tropomyosin mechanism but use Ca; stimulated by Ca in cytoplasm
= Stimulated by stretching, hormones level, action potential; Ca binds to Calmodulin protein
Ca-Calmodulin complex- activate protein Kinase; Phosphorylation activate actin/myosin interaction
= Repolarization of muscle fibers occurs through the pumping of Ca back into the SR (muscle relaxes)
In skeleton Muscle- the spread of impulse along fibers that cause a minimum contraction, a twitch
= Twitch measured in terms of tension or the force it generates
= If the twitch is generated over an adequate time period – ALL-or-None response or discrete twitch
= Rapid firing cause summation of twitches; tension increase and contraction is continuous
= Hi level of stimulation result in Tetanus- maximum contraction (no Ca from SR to S)
Strength of the contraction depend on : (1) ” of motor neuron firing (2) rate of firing
= some muscle have low level of tension, called Tonus when body at rest; neck, trunk and limb
=Muscle Tonus arise from activity of many motor units; ? time in contract & ? time relax; regulate by NS
Muscle fibers, Aerobic condition and strength
= A single muscles may contain different fibers types: SLOW and FAST-Twitch
Slow-twitch- called Red muscle; contain many myogloblin, glycogen, fats and mitochondria & well supported blood vessels
= They are resistant to fatigue so make of low tension fibers; found in most athletes
Fast-twitch- called white muscle; fatigue rapidly; high myosin-ATP activity; sprinters and weightlifters.
= Cell appear striated and are branched; so resistance to tear and high pressure
= Also contain intercalated disc-mechanical adhesion and arrangement b/w cells (gap junction)
= Conduct electricity due to low resistance to ion; they depolarize rapidly
= Also contain special cell that are pacemakers (sinus node); so heartbeat is myogenic-beat it’s own
= Rate pacemaker cell is modified by Autonomic NS; not responsible for its continuous heart beat rhythm
= Provide rigid support and attachment of muscles; 3 type of Skeleton; Hydrostatic, exo & endoskeleton
= Found in cnidarian (sea anemone), annelids (earthworms) and soft-bodied invertebrates.
= Contain incompressible fluid enclosed in a cavity surrounded muscles
Movement: Usually involves muscle arrange longitudinal (retract) and circular (extension, fig. 44.13)
= Alteration of contraction cause movement; Also found in Squid and Octopus.
Exoskeleton- is a harden outer surface to which internal muscles are attach. Joints move relative to other
Mollusk-shell grow with animal (note rings); Snails-shell made w/CaCO3 and protein
= Molluscan shell use for protein: Soft part of body is for Locomotion (hydrostatic skeleton)
Antropod-(soft-shell crab) made of cuticle but not at joints; will not grow with animal; Crustacian-CaCo3
Cuticle- 2 layers: Outer-the Epicuticle is thin prevent drying out; Inner-Endocuticle, thicken, Protein chitin
= Compose of bones connected by various joints; 206 bones; rodlike, platelike and tubelike
= Divide into 2-skeleton-Axial (Ribs, sternum, skull and vertebral column and Appendicular skeleton- bones of the Arm, leg, feet & hands, pectoral girdle.
= Endoskeleton- grows with organism; contain 2 kind of connective tissue: Cartilage and Bones
CONNECTIVE TISSUE CELLS- large matrix of protein(collagen) and polysaccharides
Cartilage- found where stiffness and resiliency is required (surface of joints)
= Found in Larynx, nose, ears, shark and rays and embryonic skeleton during development
Bones-mostly Collagen and CaPO4; reservoir for Ca for the body; In equil with Ca in the Matrix
= Under calcitonin and parathyroid control
= Cell of Bones–Osteoblast, Osteocytes, Osteoclast
Osteoblast-lay down new matrix on bone surface until cavitize (lucunae) in the bone.
Osteocytes-Cavitize osteoblast cells; remain in contact by communicating
Osteoclasts- erode and reabsorb bones; derive from WBC producing cells; for cavity and tunnel in bones
= They proceed osteoblast so involve in remodeling
BONES and CONNECTIVE Tissues–2 types
Membranous bones- form on scaffolding of connective tissue membrane; outer bone of skull
Cartilage bone- form on cartilaginous structures until gradually ossified (limb); can grow -center outward
Compact-good for compression/bending; called Haversian bone in mammal(made of unit of Haversian sys)
Cancellous bones- spongy bone; can stand compressive force
BONES And JOINTS
= Muscle work as antagonist pairs; contract and relax; Flexor-flex joints; Extensor- extend joint
Ligament- bands of connective tissue that hold joint bones together
Tenons- Connective tissue that attach muscles to bones; may span the joint Quadriceps (in knee jerk reflex)
Types of joint- Hinge, ball-in the socket, Saddle joints, Pivotal joint, Ellipsoid joint, plane joint
Hinge- knee; allow no rotation & flex in one direction; Saddle-b/w carpel bones; Plane -b/w tarsal bone
Ellipsoid-b/w phalanges; Ball-in-socket-at hips; allow movement in most direction
Pivotal- b/w 2 bones of the forearms at elbow; allow radius to rotate when wrist move side to side.
LEVER SYSTEM- demonstrate the translation of force into fast movement or over short distance.
Ratio=load arm/power arm; Arm-small ratio; much for over short distance: LEG-large; less force/short Dist
EFFECTORS of Animal kingdom
= Muscle are effector; not all effector are muscles; Function- as specialize for other function
= Defense, communication, capture and avoidance
Nematocyst-Hydra and Portuguese-man-of-war
= Coiled structure produce by cell in tentacle; Hydra-contain a spine shape trigger projectile to capture prey
= Once trigger it entangle and penetrate the prey
Chromatophores-pigment containing cell; under NS/Hormonal control; In Squids and Chameleon
= Can be use for mating or for terrestrial rivaling in some species; There are 3 types
Fixed cell- contain pigment granules-move by microfilament; high concentration means animal is pale
Some capable of Amoeboid movement; Cephalopods-muscle contractions
GLANDS- produce chemical involve in communication, defense or to capture prey
Poison glands -snakes, frogs, fish, spiders; Dendrotoxin produce from skin of frog (use by arrow of tribe)
Venom- bungarotoxin, inactivate acetylcholine receptor
Puffer fish-tetrodotoxin, blocks Na/voltage gated channel; Mollusk-Conotoxin- interferes with Ca-channel
= Mercaptan release by skunk ; Pheromone-sex hormone; use as communication in some animals/ protist
= Gland are also involve in digestion (salivary) and heat regulation (sweat glands)
= Electric eel (600 volts) and Torpedo ray and Catfish
= The electric field is use to sense environmental cues, communication, capture prey; evolve from muscles
Plants reproduce both sexually and asexually; both are important in agriculture
Grain crops such as: millet, rice, cereal & wheat all grow from seed (sexual).
The nasal orange however grows from a seedless orange seed (asexual).
SEXUAL REPRODUCTION–genetic diversity
= Meiosis and mating shuffles genes in a population; this produce diversity
= Diversity serve as environmental changes or expansion into a new environment.
Flower- a modified leaf
Carpel-stigma, style, ovary; Stamen- anthers & filament; petals and sepals; calyx- collection of sepals.
Carpel- bears the megasporangia(ovary and integument)–which produce the megasporangium
Corolla-is collection of petals ; Tepals- series of petals and sepals
= Flowers is where alternation of generation lives (gametophytes, Fig 36.1)
Gametophyte- a gamete producing generation that develop from haploid spores or sporangia.
Megasporangia- Produce the female gametophyte or megagametophyte or embryo sac.
Microsporangia–produce the male gametophyte or microgametophyte or pollen grain.
Megasporocyte? in megasporangia (ovule); produce 4 megaspores (meiosis);one spore survive.
= The megaspore undergo 3 mitosic division in a single cell (3 top, 3 bottom, 2 middle); megagametophyte
= cell wall formation lead to 7-celled gametophyte with 8 nuclei
= 3 cell at micropyle-1 egg/2 synergid cells; 3 at top-called antipodal; 2 center-produce endosperm.
The anther’s (microsporangia) microsporocyte produce microspores by meiosis-divide once then release.
POLLINATION- transfer of pollen from anther to stigma.
= In gymnosperm/angiosperm the sperm travels in pollen grains.
2 types; self-pollination (legumes, peas) and cross- pollination (wind, insect, animals and water).
In wind pollinated flowers the stigma is sticky or featherlike.
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