Plant and Animal Biology Lecture Notes PDF

Plant and animal biology lecture notes BIOL1131 Introduction, the evolution of life , and the advent of animals Taxonomy: the identification, description, nomenclature and classification of species , includes domain, kingdom , phylum, class, order, family , genus and species. Taxonomic classification : a way of grouping biological organisms based on shared characteristics , this creates order but they are not always clear and there are exceptions, it helps us understand biodiversity and complexity of life. Phylogeny : AKA evolutionary tree, represents an evolutionary hypothesis about the relationships among a set of organisms. phylogenetic tree has a tip -taxa, node, and root. - 6 kingdoms : protist, fungi, archaea, bacteria, plantae and animalia. CURRENT VIEW OF TREE OF LIFE - Its mainly bacteria vs archaea - Eukaryotes are descended frm an archaean common ancestor - Based on genomic sequencing - Suggests ancestor of life was heterotrophic unicellular prokaryote with peptidoglycan cell walls Origin of life Major transitions: fundamental changes and developments in the structure of living things that have occurred over the history of life. Ex size and complexity have increased. Natural selection does not require them as there are exceptions like archara and bacteria ORIGIN OF EUKARYOTIC CELLS - Evolved about 1-2 bilion years ago , - Have more complex structure than prokaryotes like linear dna and distinct nucleus , within cell communication networks , membrane bound organelles like chloroplasts and mitochondria Endosymbiosis : symbiosis-mutually benefited relationship , 1. Independent bacterial species began to reside within a cell 2. Smaller cell provided energy and food and larger cell provided protection 3. Relationship became obligate Evidence: - Membrane bound organelles, - Chloroplasts and mitochondria have their own circular genomes - DNA sequence of the chloroplast genome is most similar to cyanobacteria genome - DNA sequence of mitochondrial genome is most similar to a proteobacteria ORIGIN OF MULTICELLULARITY 2 methods 1. Stay together- clonal cells didn't separate after replication , parent cell divides but fails to separate during final stage of mitosis ( likely mutation) , all further replications of these cells remain linked, produces identical cells without genetic conflict. lack of genetic conflict- all further offspring are identical to any parent cell plays major role in further development of multicellularity. 2. Coming together -- free living cells come together. ANIMAL - Multicellular -- division of labour with specialised cells - Other than sponges cells form tissues and organs - Embryos develop from single celled zygote - Chemoheterotrophs- derives energy by ingesting intermediates or building blocks that is incapable of creating on its own - At least 30 phyla, with none of them being fully terrestrial and at least 21 phyla are fully aquatic - 90% of species in 9 phyla KEY TRAITS FOR DIFFERENTIATING PHYLA Symmetry - Bilateral: beetle, radial: coral polyp, no : sponge - Radially symmetrical animals often are non-motile , and live attached to a substrate - Bilaterally symmetrical animals have anterior and posterior ends - Promotes cephalisation, locomotion and concentration of sensory organs Germ layers and tissues - Germ layers form during embryological development - Endoderm- inner layer - Mesoderm- middle layer - Ectoderm- outer layer - Develop into tissues -- aggregations of similar cells connected by an extracellular matrix like muscle, blood and bone. - Animals can have layers of tissues but no cells - sponges - Diploblastic- two layers of cells with tissues but no organs - cnidaria - Triploblastic -- tissues developed from three germ layers forming complex organs- flatworms Cleavage patterns - Triploblastic animals can be protostomes or deuterostomes or a mixture of both - Both types of stomes develop very differently , deuterostomes like humans develop in a uniformly and even manner while protostomes are in a spiral manner. - 2 types of embryonic cleavage patterns: radial and spiral. Body cavities - Only in triploblastic animals - Acoelomate ( no cavity) - Pseudocoelomate -- cavity between endoderm and mesoderm - Coelomate -- cavity within the mesoderm - Animals need energy and nutrients to function -- help build or repair or reproduce - Needs are highly varied, constant ingestion to once a month - Nutrients pass into our cells thorugh diffusion : movement of solute from areas of high concentration to low concentration through a gradient until equilibrium is reached, passive , more effective as SAV is higher - Active transport can also occur to facilitate the movement of certain compounds against gradients to increase concentrations within certain cells. Methods to increase SAV - Folding -- increases surface area for diffusion - Getting flat- changes shape to increase SAV making everything inside closer to outside. - Body cavity ( coelom) -- increases proximity to fluid reservoir - Transport systems- movement of body fluids, to reduce diffusion distance , 4 different systems the digestive ( gut), excretory ( kidneys) , respiratory( lungs, gills) , circulatory ( heart , blood vessels ) COELOM 1. Decreases diffusion distances 2. Acts as a buffer or protective cushion for internal organs 3. Acts as storage reservoir for nutrients and wastes 4. Can be used as a hydrostatic skeleton 5. Annelida, mollusca, nematoda, echniodermata , chordata and arthropoda all use coelom as a reservoir but annelida and nematoda also use it as a hydrostatic skeleton TRANSPORT SYSTEMS - Digestive system - -- poriferans have no gut but create water currents to maximise rates of feeding , - Cnidarians, platyhelminths -- blind ended guts - All other phyla have a complete or a straight through gut - Echinoderms -- guts differ by diet - A simple system for them would be mouth, oesophagus stomach, intestine, rectum ad anus - Stomach can be everted for external digestion Excretory systems - Nematodes have system of simple channels - Echinoderms use their coelem and tube feet to excrete waste - Annelids and molluscs have nephridiopores or coelomoducts leading from the coelom to the exterior - Most chordates have kidneys which are modified coelomoducts Respiratory systems - Poriferans cnidarians, platyhelminths, many annelids, nematodes and echinoderms exchange gasses by diffusion - Molluscs, some annelids , arthropods and most chordates have gills or lungs - Gills and lungs vastly increase respiratory surface area Circulatory systems - Poriferans. Cnidarians , platyhelminths, nematodes and echinoderms have no specific circulatory system - Nematodes and echinoderms use body cavities ( coelomates) - Molluscs and arthropods have a simple heart and an OPEN blood system using haemolymph which flows through sinuses and bathes the tissue , the organs are surrounded by oxygenated haemolymph in the coleum - Annelids have CLOSED blood system with pumps , with aortic arches containing valves -- prevent blackflow of blood and can pump blood. Closed system means blood is moved around in a network of blood vessels, which oxygenates organs through diffusion across cell membranes. - Most chordates have a closed system , usually with a muscles heart. SECOND LECTURE - Understand the life strategies for living in the sea - Be able to recognise marine representatives from the nine major animal phyle and discuss their ecological adaptations and role Germ layers Animals may hae - Monoblastic single layer of cells but no tissue - Diploblastic two layers of cells with tissues but no organs - Triploblastic tissues developed from three germ layers forming complex organs Costs of a marine life - Lower oxygen concentrationfrom water -- solution is gills to maximise surface area - Wind waves and currents -- solution being sessile , stick on, Benefits - Stable environment - Relatively consistent temperature - Iso -- osmotic condition - No desiccation - Support for body tissues and surrounded by food Types of feed Suspension. Filter feeders remove particles from the water column with the aid of filters, traps, sticky surfaces Deposit feeders ingest deposited particulate food Suspension and filter feeding is a strategy that involves carnivory , omnivory and detrtivory Porifera sponges - Asymmetrical - Monoblastic -- single layer of cells - No tissues or organs - No nervous systems - Hermaphrodite - Structure allows thme to do efficient filter feeding, where water is drawn through pores ande exhalant through flows of water - Have suspension feeding Cnidaria - Diploblastic two tissue layers ectoderm and endoderm , no organs and blind gut - Asexual budding - Mostly colonial ,some solitary , - Cells that contain nematocysts -- harpoons , mechanism that fires out and tries to sticks into something and hold onto it. - Radially symmetrical with tentacles around mouth -- nematocysts - Suspension feeding Bryozoa - Diploblastic , no organs , blind gut - Have little feeding structure coming out of cells which give appearance of lace - Colonies of zooids which passively filter with cilia -- NO nematocysts - Suspension feeding in more static way Platyhelminthes - Triple blastic -- ectoderm, mesoderm and endoderm , blind gut , acoelomate - Bilateral , dorso ventrally flattened - Predatory - Chemical defence and can take up toxins from prey to use in defence - Hermaphrodites Mollusca - Most have shells -- external or internal and are triploblastic , coelomate with mantle cavity - Gastropod -- single shell on top of a big foot and radula - Other predatory gastropods have got radula - Cephlaopods -- head and foot - Bivalves -- two shells , mussel filter feeding and attachment , have bisous threads attached to the foot to be sessile and then filter the water and form mussel bed clump , use pseudo feces. - Calcareous shell and muscular foot , two shells and no radula - Suspension feeding active feeding, active filter feeding, habitat provision - Filter water as a behavioural defence - Two shells , no radula Nematoda - Triploblastic, coelomate, free living and parasites - Elongate round worms, no segment Sipuncula : peanut worms - Bilateral - Triploblastic - Coelomate - Filter feeders ,deposit feeders - No true segments Annelida - Triploblastic, coelomate - Segmented , which have parapodium which is used to help move and gas exchange , have hair sticking out - Sensory structure on head - Errantia and Sedentaria based on the development of the anterior appendages and life habits - Errant -- active swimmer or crawler, their gut comes out with claws and grab and suck , often predatory - Sedentary -- burrowers or tube dwellers , deposit feeders with tentacles or suspension - filter feeders with radioles , often suspension, deposit feeders - On each segment -- gas exchange, locomotion and feeding Arthropoda - Triploblastic, chitin exoskeleton, jointed appendages - Sub phylum crustacea ; two pairs of antennae and mandibulate mouthparts - Different benthic morphology - Crabs use antennae for sensing the environment - Barnacle is using the antennae to taste the chemical signature of the habitat - External skeleton , different appendages - Suspension feeders - Herbivore, detritivores, predators, Echinodermata - Triploblastic , coeloemate , radial as adults, tube feet , rough skin - Pentaradial 5 lines of symmetry - Many predators, some suspension and deposit feeders - Rough skin, - Can be herbivores like sea urchins, detritivores like sea urchins, predator like star fish. Chordata - Notochord , dorsal nerve chord, pharyngeal gill slits - Class ascidian , thick acellular body covering, incurrent and excurrent sipon, can be solitary or colonial , suspension feeders Algae - Autotrophs, - Brown algae- better for stronger lights - Green algae -- faster growing species - Red algae Plankton -- floating or weakly swimming algae, autotrophic and photosynthetic , Zooplankton- floating or weakly swimming animals heterotrophic Chemosynthetic organisms like tube worms Summary - Animals evolved in the sea - With exception of insects, invertebrate diversity is greatest in the sea - Sessile and suspension feeding are common adaptors as it is less costly , ![](media/image2.png) Life history , triohic levels and symbiosis Learning outcomes - Understand ontogeny and ontogenetic shift - Be familiar with trophic level and food webs - Be familiar with the different forms of symbiosis Ontogenic shift - Juveniles may have certain habit and adults have a different habitat - Adult mussels senssile , suspension feeding and releasing spem and egg into water , fertilisation occurs, settle on algae etc and choose to settle with other mussles , Colonial -- zooids , siphonophores, Polymorphic, colonial, hydrozoans, coloniesof four kinds of highly modified individuals ( zooids). they are dependent on each other for survival. Symbiosis Mutualistic - Coral is a symbiosis between algal cells and the cnidarian poly - Have symbiosis with algal cells where they are photosynthetic and help them with energy , coral provides host for the algal cells and uses oxygen produced by algal cells, - Both gain something from relationship. Plant and animal bio week 3 Myotomes -- blocks of muscles Craniate - Distinct head - Well developed brain protected by skull Vertebrata - Jaws - Vertebral column - Myelinated nerves- nerves that are sheathed in a wrapping of other cells , this increases the speed of the nerve signal along the nervs Agnatha -- jawless fish Cyclostome -- circle mouth Class myxini ( hagfish) - Craniate - No vertebrae Class petromyzontida (lampreys) - Craniate - Precursors of vertebrae -- nearly a vertebrate Vertebrate form and function - Same basic body plan - Variations on a constant theme - Some variation in function of body parts Tetrapod -- live on land, moved out of the water and now in the air, four limbs with separate digits, now only 3 classes with amphibia , mammalia , sauropsida -- combo of reptilia and aves Class Chondrichthyes - Cartilaginous fish-, doesn't have a large amount of cellular material inside, not serviced by blood vessels , grows really slowly can be strong - No true bone - Teeth -- denticles not fused to jaw , Class Actinopterygii - Ray finned fish - Bony skeleton - 'true' teeth Sacroptergii- fleshy finned fishes Coelacanths and lungfishes - Lobe fleshy finned fish - Mostly fossils - Lungfish closely linked to tetrapods -- 4 limbs - Pelvic girdle, skull bones, heart structure, embryology and DNA Amphibia - Salamanders and newts - Indirect development -- tadpole larvae - Most larvae fully aquatic with gills - Lose their post anal completely or dramatically reduce it - Rewire circulatory system , lost gills and have alternative route for their blolod to flow in order to pick up oxygen - Gas exchange through their skin, some nitrogenous waste removal through their skin Amniote -- a tetrapod which has an amniotic egg or a derivative -- saurosids and mammals Amniotic egg is the key to being able to survive on land full time and losing that aquatic phase of the larvae, When egg is formed, they have 4 extra embrypnic membranes , - Yolk sac -- yolk energy store - Chorion --grows under eggshell. Has evolved to allow gas exchange , - Amnion- grows around embryo - Allantois- wsaste sac Direct development-no larvae stage and the evolution of water resistant skin Fish eggs don't need shells because water and nitrogenous waste can diffuse out, but on land , shellsare needed because gravity will squish the eggs down. 3 different types of skull Anapsid -- without holes, the only holes you see are for sense, organs like hte eye, eye socket, nose Diapsid -- two holes, a temporal and dorsal opening, they are there for muscles , Synapsid -- diapsid skulls where the two holes merged , Mammals - Large biomass - Characterised by hair and mammary glands - Evolved from mammal like reptiles - 2 sub classes, - protheria ( monotremes) : lay eggs, platypus and echidnas - Theria bear live young, embryso nourished from wall of uterus -- through placenta - Methatheria ( marsupials ) -- yolk sac placenta, young born less developed , early foetal stage - Eutheria ( placentals ) : true chorio-allantoic placenta, young born more developed stage Mammary glands - Secretes milk to feed young - Provides nutrition and antibodies - Antibodies to prime the immune system of the young, - Endothermic -- regulate their body temperature using metabolic heat production, other vertebrates are ectotherms Why are vertebrates important Diversity of form : vertebrates show all feeding strategies - Found in all ecosystems - Influence the ecosystem in which they live- moving soil and affecting plants - Food source for other organisms - Provide pollination service - Apex predators -- top down control - Facilitate survival of other species - Oxygen, activity level, body mass, cellular complexity , phylogeny, body and ambient temperature - Total of all biochemical reactions occurring in the body of an animal - Subsets therefore for glucose metabolism - If metabolic rate of an animal is a measure of its overall cellular metabolism , 1. Heat production 2. Oxygen consumption 3. Carbon dioxide production 4. Energy balance 5. Substrate utilisation 6. Metabolic water production Heat production - Antoine Lavoisier- named oxygen and hydrogen , helped create metric system and the first law thermodynamics - Measured direct heat production using a simple bug ingenious method Energy balance, in out balance - Possible to determine the metabolic rate of an animal by its overall energy balance, - Food, drink, waste, urine , growth, reproduction , - Unaccounted energy = metabolic energy **Determinants of metabolic rate** 1. Activity level 2. Body mass 3. Taxonomy 4. Temperature **Activity level** Metabolic rate varies from minimal/basal level to maximal/summit level **Body mass** Larger animals have a larger metabolic rate than smaller animals Determinants of metabolic rate- body mass Many physiological processes proportional to metabolic rate, not body mass Metabolic mass is the physiologically related mass, it changes less rapidly than actual body mass. Metabolic mass decreases per gramme of body weight as body weight increases **[Cellular grade ]** Same effect of mass on metabolism for almost all animals However, metabolic rate varies dramatically for 3 groups of animals : unicellular organisms, poikilotherms -- cold blooded , homeotherms -- warm blooded **Temperature** Chemical reactions are exponentially faster at higher temperatures Activity Locomotion has a major metabolic cost , Swimming, slithering, walkin, gliding, flying Terrestrial locomotion is based on level mechanics Aquatic and aerial locomotion have similar fluid dynamics both with similar concept, swimming is based on drag, flying is based on lift. Water is more dense than air , more drag in water Maintaining altitude is lift. swimming - Animals can swim by a variety of means, including - Jet propulsion -- squeezing water out of a chamber - Drag from limbs, body or fin undulations - Flying using lift Jet propulsion Jellyfish cnidaria - Circular muscles around bell Cephlapods ( mollusca ) - Octopus, squid, cuttlefish, - Circular muscles around mantle , siphon for direction - Scallops - Adductor muscles pull shells together, forces water from the shells Drag - From limbs, body , fins - Drag in water counteracted by thrust - Like a rowing oar, limbs, fins and bodies - Push back on water , drag provides forward force Flying underwater - Less common - Uses hydrofoil -- wing to create lift for propulsion - Flying only works for relatively big aquatic animals Flying in air - Uses fluid dynamic force - Counteracts weight , overcomes drag of the animal , - Speed of air going over that aerofoil surface, move faster over top of surface it creates negative pressure which is what produces the lift and drag - Using air currents generated by land mass that gets really hot - Hot air heats up land surface and ascends because of the displacement of cold air - Parachuting - Drag slows fall of object - Similar rowing - Can be turned into gliding - Various animals glide - Gliding uses part of the lift force to overcome drag sp animal maintains speed - Insufficient lift to balance weight so animals move forward and descends - Gliding uses less energy than powered flight Power flight - Provide extra energy through their wind movements to maintain their horizontal position , - Lift = body weight and forward velocity - Flapping that allows air movement across the aerofoil surface. - Rate of air moving depends on speed of muscles that can work , 2 theories for flying Ground up - Leaping dinosaurs - Running, leaping, flying Tree down - Gliding mammals - climbing, gliding and flying running - limbs support / lift body off ground and provide forward movement - lift pattern can confer stability , - centre of mass held in tripod formed by three limbs contacting ground - 2 strokes, the thrust and the recovery - Thrust is when leg is against the ground and muscles are pushing against the ground - Recovery is when leg is lifted off the ground and then moved forward Hopping - Wide range of speeds with no effect of the metabolic cost - Tendons act like springs, store elastic energy for rebound - Hopping at high speed is very economical Summary - Swimming is least energy per gramme of body mass as they don't need to provide lift , - Every stroke provided is thrust - Running your level has to have recovery stroke which has no forward momentum. **[NEW LECTURE]** - Understand the gaseous composition of air and water - Understand diffusion and convection in air and water - Appreciate the diverse respiratory strategies of animals - Understand similarities and differences for oxygen and carbon dioxide exchange Gas exchange "respiration" - Supply of oxygen to and - Removal or carbon dioxide from all cells of the body - Occurs over living cells -- wet surfaces - In aquatic habitats, oxygen dissolved in water so no issue with water - In terrestrial habitats, oxygen in air , air with less than 100% relative humidity results in loss of water by evaporation during respiration - Respiratory gas exchange often requires mechanisms to limit water vapour loss. Fear of death by dessication, Gases in dry air At sea level,as you go higher in elevation the pressure decreases and concentrations are going to decrease. All the dissolved gases are much lower in sea water. Due to temperature [As water gets hotter, the gases start to leave the water , so cold water has more dissolved oxygen than hot water, vice versa with CO2 ] 100% relative humidity is 0.03 mils of water per litre of air , Partial pressures of gases Partial pressure= fraction of total atmospheric pressure - Physiologically relevant measure not %, concentration, - Gases depend on pressure, as elevation increases the amount of gas decreases, Principles of gas exchange 1. Diffusion -- exchange of gases by the random thermal motion of molevules in air , its temperature dependent, passive physical process , movement of oxygen from lungs into blood is an example. Rate of diffusion occurs depends on change in quantity over time , depends on partial pressure Diffusion depends on partial pressure difference, area for exchange and distance over which diffusion occurs 2. Onvection -- exchange of gases and fluids by movement , active process, heat is warming air causing it to move up and displaces the cold water where oxygen was removed and CO2 was placed in it , - Most animals have convection mechanism to move water or air over their respiratory surfac - Minimises depletion of oxygen and build up of carbon dioxide near gas exchange surfaces- this movement is called respiratory ventilation , Oxygen cascade -- diffusion Oxygen delivefry from external environment ( air or water ) to mitochondria inside cells following the oxygen cascade. oxygen cascade happens inside the mitochondria cell where there is a combo of two processes -- diffusion and convection 2 steps in oxygen cascade 1. Across respiratory surface 2. Diffusion from blood to cell/mitochondria - Studies how body size affects physics and chemistry of organisms , - Bigger size Improves muscle and limb length but complicates gas and nutrient exchange - Gas impermeable surfaces like shells and thick skin - SAV ratio decreases rapidly , hard for diffusion - Complex circulatory systems needed to pump fluids efficiently - Small and flat animals rely on diffusion while aquatic and some terrestrial animals use cutaneous gas exchange ( across skin) Surface respiratory structures in animals Air breathing insects Trachea - Rigid internal branching tubes - oxygen and carbon dioxide diffuses along - Internal tube = trachea -- rigid branching tubes to all cells - Diffusive gas exchange - Dosent work for big insects Aquatic animals Evaginated gill - Often protected by a rigid covering-carapace - Water keeps gill surfaces separated - External water flow across gill filaments is in opposite direction to internal blood flow- counter current exchange Gill anatomy - Water is drawn into mouth, passes through gill arches and exits through operculum - Gill arches have numerous plate like extensions -- gill filaments which are covered by small gill lamellae , - Lamellae -- site of gas exchange between blood and water - External water flow across lamellae in opposite direction to internal blood flow -- counter current exchange Counter current exchange - Maximise exchange - Water and blood flow in opposite directions to maximise exchange gases, salts , heat and other metabolites Co current exchange - Water and blood flow in same direction - Exchange leads to equalised levels - Counter current is more efficient - 50% diffusion Air breathing animals Invaginated lungs - Developed as internal structures from out pocketing of gut , initially used for air breathing and absorbing nutrients - Opening : pneumostome - Body wall compression helps with air movement -- muscles in throat or around body compress and relax to swallow air and expel it more efficiently than pumping Evolution of lungs in fish - Some fish have converted lungs into swim bladders for buoyancy regulation - Other fish have remodified swim bladders back into lungs for air breathing - Air gulping: some fish absorb oxygen directly through their gut while also processing food - Few fish also breathe through modified gills, skin or gut Respiratory tree connected to rectum Water is sucked in and expelled using convection for gas exchange Respiratory structures- amphibiance - Two stroke buccal pump - Throat muscle to bring air into the throat , which is then swallowed down into lung - Two step process, - Inefficient because youre not expelling lungs content before you put the fresh air in. - Constantly remixing fresh air with high oxygen from out side atmosphere with stale air high in CO2 in lungs - Get most of their respiration across their skin, high SAV, Respiratory surfaces- reptiles - Have more advanced system than amphibians - Lost the ability to breathe through skin as its covered in scales , - Lung is sometimes a simple sac - But extensive folding of lung surface high SAV - Typically rib cage muscles expand and collapse lungs - Few species like goannas can use buccal pump to force air into lungs, - Crocodiles have more complicated system for lung ventilation, they have a rib cage and their lungs are connected to live by diaphragmatic muscles which contract and expand lungs by pulling on the liver Respiratory surfaces- mammals - Lung surface divided into numerous small sacs called alveoli - Alveoli increase SAV for gas exchange - Breathing is still tidal - Air entering and exiting lungs mixed - Can never compress our lungs 100% because of alveoli, can never get rid of all the air, Birds - Lungs are rigid and connected to numerous extensive air sacs - Have soft anterior and post anterior air sacs , - Provides unidirectional -- one way airflow through lung tissue in one continuous flow - Air entering does not mix with air exiting lung - 1\. When they breathe, air goes to posterior air sacs, into lungs filled with parabronchi where gas exchange occurs, next breathe out they go to anterior air sacs , next breathe out - Blood flow is perpendicular to air flow -- cross current air flow - Not counter current, bird lung is more efficient than mammal lungs - Can breathe at much higher altitudes than mammals Mammals and the bends - Gases dissolve into bodily fluids - When surfacing , pressuring is reduced - Bubbles in small blood vessels cause pain = the bends - Whales avoid this by collapsing their lungs when they dive so there is no gas exchange from their lungs - Breathe a lot , get a lot of oxygen into blood and muscles, surviving purely on dissolved gases in their blood, to avoid bends CIRCULATORY SYSTEM Learning outcomes - Understand basic solution chemistry - Appreciate three ' environments' intercellular, extra cellular and external - Understand physics of fluid flow in tubes -- vessels - Understand open and closed circulatory system s in animals - Appreciate roles of gravity and blood pressure Body water content and solute levels must be maintained within a tolerable range for normal cellular functions Intracellular environment and external environments - But has different concentrations of ions and organic solutes - Bony fish have 1/3 of osmotic concentration than sea water so there will be more energy costs for them as they must constantly shift more salts around to maintain lower level of saltiness in body fluids - Chlorine and sodium are much higher in salt water than in organisms Extracellular environment and external environments - Extracellular environment is like seawater for some marine animals - Can be very different to seawater for other marine animals like bony fish - Not a lot of change in salt concentrations of extracellular fluids , - Bony fish are very different, they have salt pumps that change salt concentration in extracellular and in intercellular - All of them changes intracellular for optimal conditions for metabolic ioschemical reactions. Osmo conforming - Solute composition of extra cellular fluids is same as ambience medium, even if it changes - Can increase or decrease other components in the blood so that osmostic pressure between sea water and your internal fluids are the same Osmo regulation - Solute composition of exracellular fluid is different from ambient medium, especially if it changes - Energetically expensive -- ion pumps need energy - Salt pumps are used to maintain a certain internal environment across a range of concentrations of salt and other stuff in water. Iono conforming - Ionic composition of extracellular fluid is same as ambient medium, even if the composition of the medium changes - Note high ion concentrations interfere with proteins - Especially marine species -- sea does not change much Iono regulating - Especially estuarine and fresh water species- salts change enomously depending on rainfall and evaporation - Ionic composition of extracellular fluid is different from ambient medum, especially if the composition of the medium changes. Osmo conform and iono conform - Most marine invertebrates osmoconform and ionoconform to seawaer - Hagfish and most basal primitive vertebrates , essentially do not gain or lose water or ions -- in equilibrium Osmo conform -- iono regulate - Sharks , - Urea , trimethylamine, fill the osmotic gap - In water balance with seawater - Gain ions, lose urea by diffusion - Allows urea -- bad thing as it ingterferes with protein function , TMAO interacts with urea and decreases its negative consequences, which means it can keep overall amount of solutes in blood similar to in sea water , Bony fish moved into estuaries, they have 1/3 of salts in blood compared to seawater, they osmo conformed in those fresh water environments Oso regulate -- iono regulate -- fresh water Passive - Gain water by osmosis through gills - ;ose ions by diffusion - Higher water pressure and less salt in body fluids compared to sea water - Water want to flow out of body tissues and into sea water - Have water leave the blood in the gills and going out into sea water , lose water by breathing , - Must drink water to replenish water lost Active regulation - Have salt pumps in gills that actively secrete salt back into the ocean - Glomerulus gets rid of particular salts so they can void salts out of their body to maintain that low salt level inside blood, - Lose excesss water as urine - Gain ions by active ion uptake in gills, kidneys Bony fish moved out of estuaries and into fresh water, - More salts in body , tissues and blood compared to salt in fresh water of river - Water pressure high, water wants to go in gills by diffusion as they breathe, salts can diffuse out of body and into fresh water - Salt pumps are reversed and try to grab any salt they find to uptake into bodies - In kidneys, glomerulus, they have tubules that have salt pumps to extract all the salts coming out of the urine and into blood , Brine shrimp - Special glands on legs and in gut to dump salt when it gets high in concentration and to pick up salt when its low in concentration Terrestrial - Water limited - Bodies have evolved to stop water loss - Actively drink because constantly losing water into air - Can derive water metabolically when they metabolise their food - Water loss through evaporation in lungs - Constantly dump water into lungs to maintain 100% humidity so cells don't die - Los water through urine, faecesm Adaptations - Concentrated faeces, - Water from food - Relative humidity in air can cause condensation from dawn o dusk that animals can drink from as it occurs on their skin , Circulatory system - Must be transported from entry location to all organs in the animal - Diffusion transport water and solute slowly and over short distance - Convection required to transport of water and solutes rapidly over longer distances - Bulk flow -- convection in animals is usually accomplished by circuit loop -- unidirectional, not tidal , circulatory system Small and flat animals, rely on diffusion for gas exchange across body surface Larger animals Circulatory system has many roles Transport - Gas - Nutrient and waste, - Hormon - Immune cells and components - Heat Blood pressure - Hydrostatic skeleton - Locomotion - Cloting components Components of circulatory system Heart: pumps blood through blood vessel Blood vessel : conduits for blood flow Arteries: away from heart, to organs through capillaries if closed, to veins -- towards heart Closed - Complete vessel network - Vessels from heart , capillaries into organs , back to heart - Blood cells remain within vessels / circulatory system - Annelids Open - Incomplete vessel network - Vessels from heart, NO capillaries, vessels back to heart , - Blood cells leave vessels, blood percolates through organ and tissue spaces, returns to vessels to enter heart - Arthropods - Blood bathes the organs directly , Vertebrate circulatory system Most basal vertebrates have slightly open circulatory system , all other vertebrates have closed circulatory system Increasing efficiency - Fishes have single pump, single circuit , - Basal tetrapods have single pump , double circuits - Mammlas and birds have double pump, double circuits Fish circulatory systems Fishes have simple circulation of single pump, single circuit - Heart pumps blood to gills, blood is oxygenated - Blood flows to body to deliver oxygen to organs - Heart is 2 chambered - Thin walled atrium receives blood - Thick walled ventricle pumps blood to gills, to body , most of the pulsatile blood pressure Amphibians They have single pump, double circuit system , - Heart pumps blood to lungs (larvae-gills) and skin, blood is oxygenated and returns to heart -- first circuit - Second circuit -- heart pumps blood to body to deliver oxygen to the organs Heart has 3 chambers Right atrium to ventricle to lungs and skin ;eft atrium to ventricle to body Ventricle structure and spinal valve keep oxygenated and deoxygenated blood partly separated - Some mixing of oxygenated and deoxygenated blood Reptiles -- not crocodiles , Have simipler circulatory systems than amphibians, Single pump, double circuit system - Heart pumps blood to lungs , blood is oxygenated and returns to heart , first circuit - Heart pumps blolod to body to deliver oxygen to organs -- second circuit Heart has 3 chambers Right atrium to ventricle to lungs Left atrium to ventricle to body Ventricle has 3 chambers, keeps oxygenated and deoxygenated blood well separated Crocodilians have independently evolved for 4 chambered hearts , proper double pump system with the right and left ventricles showing complete separation of that oxygenated and deoxygenated blood. Mammals and birds circulatory system - Most complex - Double pump, double circuit system - Heart pumps blood to lungs, blood is oxygenated and returns to heart -- first circuit - Heart pumps blood to body to deliver oxygen to the organs -- second circuit heart has 4 chambers - Right atrium to right ventricle to lungs - Left atrium to left ventricle to body - Oxygenated and deoxygenated blood is well separated - Unable to by\[ass lungs ( except embryonic circulatory system) - Birds opposite to mammals Blood pressure This heart generates blood pressure to push blood through the vessel - High pressure in arteries - Low pressure in veins - Due to high resistance in capillaries Double pump = higher blood pressure as well as separation of oxy/deoxy blood As a large vessel breaks up into many smaller vessels, artery to arterioles to capillaries, massively increasing surface area of vessel relative to volume of blood moving through causing a drop in blood pressure. Blood pressure and gravity - Arterial blood pressure pushes blood against gravity to brain - Small animals- trivial - Humans need 50mm of Hg blood pressure - Giraffes need 200mm Hg WEEK 4 Nutrition and digestion Learning outcomes - Understand definitions, differences and strategies of - Food , vitamins and minerals - Heterotroph, autotroph and chemotrophs - Digestive tracts for carnivores, omnivores and herbivores - Foregut and hindgut fermentation Organic matter and energy - Animals need other organic matter and energy to survive - Energy can be acquired by animals in different ways - Chemotrophs - Autotrophs - Heterotrophs Chemotrophs - Real chemotrophs are bacteria, they synthesise organic materials from simple chemicals - Various invertebrate animals like annelid worms, bivalve molluscs form symbiotic relationships with bacteria - Animals host gains some or all of their energy and nutrients from symbiont, often through simple compounds, - Pogonophora's -- gian tube worms lack feeding anatomy, gut , adapted for hosting bacteria Autotrophs - Photoautotrophs are cyanobacteria, single celled protists like algae - Synthesise organic maerials from photosynteiss - Various invertebrate animals like corals form symbiotic relationships with photoautotrophs - Animal host gains some or all of their energy and nutrients from symbiont, Heterotrophs - All animals - Gain their energy by consuming organic material - Insectivores- carnivores specialised on insects - Saprozoic animals -- obtain organic chemicals by absorption across the body surface eg gutless worm, Carnivorous plants - Few plants - Digest invertebrates usually insects to gain nitrogen and minerals - Typically live in nutrient deficient freshwater wetlands, bogs and marshes Water Few organisms survive outside of standard physico -- chemical state of water - Cryptobiosis = hidden life - Anhydrobiosis = absence of water - Osmobiosis = high solute concentration - Cryobiosis = frozen water - Anoxybiosis = lack of oxygen - All specialised, highly adapted to their extreme habitats Organic matter - Provides nutrients in four macromolecules - Carbohydrates - Proteins - Lipids - Nucleic acid - Food provides nutrients but composition of food varies greatly Vitamins - Vital for life but isnt synthesised by particular species - Organic compouns - Amino acids - Essential for physiological function - Not made by animals, needed in trace amounts - Humans unable to synthesise vitamn c , animals can - Some animals obtain all of their vitamins from symbiotic microorganisms Minerals - Many minerals required Major minerals - Calcium and phosphorous (bone), potassium, sodium, chlorine , - Minor minerals , trace elements, iron, cobalt , nickel, copper, zinc, Herbivores - Often do not obtain required nutrients from their diet , as plants - \- lack specific compounds like sodium and chloride, - Most herbivores eat dirt to get minerals into their diet Nutrient assimilation Heterotrophic animals can assimilate nutrients into their body in three ways 1. Trans-epithelial absorption : some saprozoic animals absorb nutrients across their body surface , can happen inside gut of animals like us -intracellular digestion, Many internal parasites absorb. Nutrients across body surface like tapeworms 2. Intracellular digestion : large food particles are absorbed into the cell by phagocytosis ( solid particles) or pinocytosis (liquids) 3. Extracellular digestion : specialised digestive tract ( gut) prvides ingestion and digestion of food particles much larger than individual cells, the small products of digestion are absorbed into the gut cells. Extracellular digestion - Most multicellular animals use extracellular digestion of food - Specialised digestive tract(gut) allows ingestion and digestion of food particles much larger than individual cells - Food is generally digested into its subunits like amino acids and fatty acids, inside the gut by enzymes secreted from gut cells - These sub units are absorbed across gut wall Some animals have incomplete gut - Blind sac with single opening - Functions as both a mouth and anus - Cnidaria and Platyhelminthes s Most animals have a complete gut - Tube with two openings - One is specialised mouth - Specialised anus - One way flow of food - Specialisation of different parts of the gut for different functions - Some animals have specialised sections for difficult to digest materials like cellulose, keratin and bees wax, One way gut with regional specialisation Mouth: reception and mechanical processing Oesophagus: transport Crop: stomach Stomach : chemical breakdown , protein Gizzard: mechanical breakdown Intestine: chemical breakdown, nutrient absorption, water reabsorption , consolidation of faeces Rectum and cloaca : storage and elimination of faeces INDIGESTIBLE PROTEINS Silk: from spider webs , some animals like spiders can digest it using silkase enzymes Chitin : in fungi cell walls and arthropod exoskeletons , in some fungivores and insectivores, Indigestible carbohydates - Most carbohydrates are easy to digest like starch - Some plant carbohydrates such as cellulose are impossible for normal animal enzymes to break apart into monosaccharide subunits -- because of different bond structure Digesting indigestible carbohydrates - Plant cell made of cellulose -- abundant macromolecule for organic life on earth. - Comprises up to 70% of terrestrial plant matter - So huge food resource - Some animals have evolved specialised digestive systems like ruminants and pseudo-ruminants Digestive modifications for specialised herbivores 1. Symbionts able to digest cellulose 2. Fermentation chamber to house symbionts comfortably Located in gut , along with food 3. Mechanisms to mix and reprocess digesta Rumination 4. Slow passage rate: increased gut length STEPS 1 Symbionts Symbiotic relationship between host and microorganism Ruminant host -- provides environment Microbes -- provide cellulose digestion 2 Fermentation chamber Can be located in three positions along gut 1. Stomach 2. Caecum 3. Hind gut )colon) Promotes microbial growth due to - Relatively stable temperature - Readily available water and nutrients - Through saliva and digestive secretions 3 mixing mechanism - Mechanism to mix and reprocess digesta -- rumination - Mammals lack a gizzard, so much regurgitate for remastication = second mechanical processing l. - Contractions of smooth muscle moves food from mouth to anus. = peristalsis , 4 passage rate - Slow passage rate - Could decrease speed of muscular persistalsis - Instead length of digestive tract increased - Food retained in gut for sufficient time to allow digestion - Fast enough to provide enough nutrients to the microbes and host. - Termites are very efficient, camel and alpaca at the other end Artiodactyl : bovids, cervids, giraffes Stylopodia: camels, llama , alpaca - Foregut fermenters - Most specialised mammalian cellulose digestion Stomach is 4 chambered in sequence, 1. Rumen -- paunch 2. Reticulum -- honey comb, same fnctional space for fermentation , some absorption 3. Omasum aka bible , one way step , once chyme has moved from reticulum to omasum it dosent come back , Triple =1,2,3 4. Abdomasum -maw - Sloths, colobid, langur monkeys, rodents - Microbial symbiotes in stomach and or caecum - Few pseudo ruminants regurgitate food to rechew it - Some macropods ' ruminate' a little Hind gut fermenters - Microbial fermentation in caecum or large intestine - Large caecum and or long intestine increase fermentation volume in general - \- small animals use caecum , - Intermediate size animals use either or both - Large animals use large intestine - Behind the stomach - First part of intestine like carnivores where simple sugar, fatty acids, and amino acids are absorbed tehre - Then fermentation chamber wher we get volatile fatty acids absorbed through hind gut , but because its passed the stomach the microbes can only be digested properly in the stomach itself , and it is one way , they will defecate and lose the energy filled microbes, - So rabbits eat their own faeces to regain the microbes again, have two types of poo, one that's been past te gut once and past the gut twice. Temperature , themoregulation and stressful environments Learning outcomes - Understand the physics of temperature and heat - Understand the concept of Q10 - Appreciate thermal scale for life - Conceptually differentiate ectotherm from endotherm - Appreciate thermal strategies of ectotherms - Appreciate how animals survive stressful environments - Seasonal, metabolic depression, cold, heta , hypoxia Temperature determine stae of water , it's the average kinetic movement of a molevule Heat is the total kinetic energy content of all molecules Temperature dosent equal heat , Q10 - Quantifying temperature effect - Chemical reactions occur exponentially faster at higher tejperatures - Is the proportional increase in reaction rate (K) over a 10 degree change in temperature - For physical reactions like diffusion - For biological reactions with enxymes Biological chemical reactions have narrow range of temperature tolerance from 0 to 50 degrees c Thermophiles 30-50 Mesophilse 10-30 , Psychrophiles 0 -- 10 Thermophiles at high temperatures keep protein structure stale with fewer hydrogen ( weak) bonds, more hydrophobic ( strong) bonds = increase rigidity of proteins, they don't denature as you increae the temperature Psychrophiles at low temperatures keep protein structure stable with - More hydrogen onds - Fewer hydrophobic bonds which increase functional flexibility of proteins Poikilotherm Animals have variable body temperature, usually depending on the environment Homeotherm Animal shave constant body temperature, usually not depending on the environment Ectotherm Temperature of animal is determined by heat exchange with the environment , thermally passive, they thermoconform to the environmental temperature, some can achieve a particular preferred body temperature, using themerla variation withi environment like solar radiation to thermoregulate , often same temperature as environment because of their low heat production. Low metabolic rate , body temperature increases linearly with ambient temperature, metabolic rate increases exponentially with temperature Q10 -2.5 Aquatic ectotherms - Have same temperature as their environment due to - Low heat production - High thermal conductivity of water - May thermoregulate bahviourally by entering or exiting water at different times as warm waters at top and cold is at the bottom - Requires water with different temperature - Thermoclines in still water Terrestrial ectotherms - Air is light not bulky like water, dosent have high thermal mass like water , much easier to behaviourally thermos regulate to maintain a more consistengt temperature - Often have different temperatures as environment , thermoregulate behaviourally due to - Lower thermal conductivity of air - Moer variation in environmental temperatures - Solar radiation and differential heating - Heliotherms bask in sun - Thigmotherms press body to warm rocks or soil - Endotherm Temperature of anials is determined by heat produced by the animal, not by environmental temperature , thermally active, use physiology like metabolic heat to thermoregulate and maintain constant temperature, independent of environmental temperature , Use internal heat production to regulate a high and constant body temperature, generally 36 to 42 degeres, independent evolution of mammals, birds and possible pterosaurs and some dinosaurs Metabolic rate = heat production Increases at low temperatures to match heat loss Constant in thermoneutral zone Increases at high tempertaures due to cost f heat loss Metabolic rate depends on your ambient temperature. Heat conservation - First step in endothermy is heat conservation, - Fur and feather are insulation to prevent metabolic heat loss Dinosaurs ![A screenshot of a graph Description automatically generated](media/image4.png) Dinosaurs - Many large reptiles were gigantothemrs - Large animals have low SAV , so reduced heat loss , - Large reptiles have higher body temperatures from internal heat production - Large dinosaurs would have had high body temperatures Endotherms -- hibernation Hibernating mammals like bears, squirrels , drop internal temperature to save metabolic energy , driven by low food availability Temporary endotherms Dung beetles are endothermic while they are walking- behavioural - Many insects are endothermic when active, ectothermic when resting - Some reptiles, snakes brood their eggs , sit on top of their eggs and shiver which increase metabolic heat and heat their eggs so they develop faster Regional endothermic - Mako sharks, tuna and sword fish - Partially endothermic - Use metabolic heat to warm part of their body - Usually warm muscles but also brain and eyes - Counter current blood flow retains heat - Large animals with low surface area to volume ratio reduce heat loss Environmenta challenges - Metabolic depression in extermes - Seasonal acclimatisation - Cold peripheral hypothermia and topor, hibernation - Freezing cold - Heat avoid , evaporation - Hypoxida , burrowing, altitude, - Climate change Freezing cold - Sea water freezes -1.86 - Tissue freezing, extracellular fluids can freee, intracellular fluids must not freeze - Wood frogs - Don't want ice crystals to form in your living tissue, cells secret various anti freeze agents to keep the cells away from forming ice , Heat - Proteins can denature - Get off the ground,burrow underground, move above ground, minimise contact - Evaporation water has specific heat : salivate , pant , sweat , Climate change - Warming of atmosphere has two effects on rainfall and water wavailability on land - Warm air can absorb larger amounts of water , less water falls as rain - Drier parts of the equatorial zone and parts near the polar zones are getting wetter , - Things are getting better for ectotherms in antarctica , - NEW LECTURE - ANIAL DEVLEOPMENT AND REPRODUCTION - Learning outcomes - Understand how gametes are produced, find each other and what happens at fertilisation - Be able to envisage the early stages of development from fertilised egg to late gastrula - Understand how early development differs in protostomes and deuterostomes - Appreciate the processes involved in the production of an organised embryo from a single celled zygote - - Blast = ball of cells in development - Blastula = ball of cells itself - Blastopore is a particulare structure - Blastocoel , coel is a cavity , so it's a cavity within ball of cells - FERTILISATION - Sexual reproduction - Male and female gametes- sperm and egg are - Produced by male and female gonads - Released through gonoducts -- vas deferns and oviducts - - Meiosis - Reduces amount of genetic information in a cell by reducing chromsosmes by half from diplod to haploid - Mixes up combination of allels by recombination (pieces of DNA are broken and recombined to produce new combination of alleles) creating genetic diversity at the level of genes - The gonads are the only place in the animal body where meiosis occurs , function is solely to produce gametes - Recombination is important because it creates variation in population and allows evolution to happen , - To produce gametes - 6 stages in total , - Happens in germ cells - Purpose is sexual reproduction - Produces 4 haploid daughter cells - Genetic variation increases - - Mitosis - DNA is duplicated in cell and divided equally between two cells - Organsied series of evets called the cell cycle - Cell cycle triggered by presence of certain growth factors or other signals that indicate that the production of new cells is needed - Occurs in somatic cells -- fat cells, blood, skin - Necessary to replace dead cells, damaged cells or cells that have short life span - New cels, fix damaged cells , - 4 stages in total - Happens in somatic cells - Purpose is cellular proliferation - Produces 2 diploid daughter cells - - - Both - Start with a parent cell single - Produce new cells - Similar basic steps - - Meiosis and mitosis s - Cell division - Organisms grow and reproduce through cell division , in eukaryoic cellsm eh production of new cells occur as a result of them - Processe are similar but distinct - - Gametogenesis - Occurs in primary sex organs 0 gonads - Production of gametes by primordial germ cells and it involves both mitosis and meiosis - Spermatogenesis ( production of sperm) - Oogenesis ( production of eggs ) - Oogenesis - Primary oocyte ( product of mitotic divsiisons -- end during gestation) - First melotic division -- primary oocyte gives rise to secondary oocyte AND first polar body - Second meiotic division- secondary oocyte gives rise to ovum and second polar body - First polar body usually gives rise to two more polar bodies - - Egg maturation - Huge increase in size - Increase I organelles - Increase in nutritive materials - Development of protective extracellular membranes - - Spermatogenesis - Primary spermatocyte ( product of mitotic divisions) - First meiotic division -- primary spermatocyte gives rise to secondary spermatocytes - Second meiotic division -- secondary spermatocytes give rise to eprmatids - - Spermatocyte - Loss of most of cytoplasm - Development of log flagellum -- tail - Formation of secretory acrosome at anterior of head section - - Eggs are full of nutrients and trying to ake it as nutrient rich as possible but its immobile while sperm which is tiny with masses of energy , directing that nucleus to et to the egg and insert inside egg. - - A sperm must - Find an egg - Find the right egg - Prevent other sperm from fertilising the right egg - This is easier when fertilisation is internal - - Needs quantity and proximity , chemical signalling for coral , - Egg is producing sugas, lipids , proteins on the surface that will help to attract the right sperm and repel the incorrect sperm - If chemicals don't match the sperm they will go off and try to find something else - - External vs internal - External -- outside body like corals and frogs, tend to have thicker membrnaes because they have to be protected from the salt water. - Internal -- inside body like sperm goes to female reproductive tract , much more protetcted so jelly coat is much thinner - Several options -- intromittent organ ( penis, claspers) pr spermatophore ( sperm packet) pr injected through body wall - - - Fertilisation -- fusion of egg and sperm - Step 1. - Egg activation - Inactive egg is activated by fusion of plasma membranes of egg and sperm - Resumes synthetic activity - Step 2. nuclear fusion - Pronuclei of egg and sperm fuse - Creates diploid zygote - Chemicals that dissolve the membranes so they can fuse together and sperm can insert its acrosomal processes. - Acrsomal processes have to go past the egg jelly coat so it can make contact with the actual egg plasma membrane and the nucleus from sperm can come out and go straight into the egg , where the tail falls out -- mitochondria falls away. - - Two different sources of genetic materia give you lots of information about evolutionary backgrounds of different speies , - Once nucleus is inside, put up barriers, have electric fence type barrier which is waves of calcium ions, calcium is positively charged and repeles the spem away from the egg and released when calcium is released next to the membrane and have a fertilisation membrane which is much slower and much longer lasting - The calcium fence is very expensive to do that , and cant last a long time but it is a very quick response , long enough until you get fertilisation membrane up. - While the calcium fence is occuirng , there is cortical granules that are ready to release themselves to insert into the membrane. - The psemr goes in , breaking the membrane which triggers the calcium release and then calcium release triggers cortical granules going in , - - Diploid zygote has a full set of chromosomes , one set from each parent - Recombination allows alleles to combine in new arrangements to produce a unique genotype - - Once fertilisation has occurred - Zgote must - Proliferate to make many cells - Eliminate unwanted cells - Differentiate the remaining cells to form different types of cells - Develop tissues, organs and body structures - - Blastula formulation ( cleavage - Exponential growth , cells grow extremely quickly - Super efficient - 2 types of cleavage , radila and spiral - Cleavage is extremely organsed , protosome is mouth first-spiral , deutrosomes -radial is the mouth forms second, anus is the other end of the digestive tube, they both form in the same place at the bottom - - For sea cucumber making a blastula - VVHVHVH - Every cell divides at every division -- creating exponential growth. - - Sea urchin : making a blastula - VVH V/H H/V H/V - Where after the horixontal top half is cleaved vertical and botto half is cleaved horizontally. - - - Different species have different amounts of yolk in their eggs and that contributes to their cleavage pattern. - Amphibians have bit of yolk. Fish repties and birds have ots of yolk. mammlas have very sparse yolk that's distributed euqlalay throughout egg , - Yolk will determine the pattern of cleavage , - BIRDS - Little blobl of blastula sitting on top of yolk because yolk dosent get cut up - - FROGS - Have bit of yolk , really concentrated in botto of egg compared to top. - First cleavage line isnt complete but the second line has already started. Creates a gradien of cleavage so the top divides much quicker than the bottom and you end up with smaller cells at the top and bigger cells at the bottom - Blastic seal is really asymmetrical , - Yolk is concentrated at the bottom and impedes the process of those cleavage furrows. - Pattern of blastic seal at top is important - Meroblastic- incomplete cleavage - Teloecitha -- lots of yolk concentrated at one end of egg - Division happens on top of the yolk , spread out like a sheet - Mammals - Rotational cleavae - Ends. Up with cells being slightly assymetrical - Placeta : make a placenta so they hae to have part of the egg that's ready to implant into uterus wall , - - Gastrulation - Rearrangement of cells in the blastula to form a gastrula - Blastula : no specialised tisses and no organs except for mammal internal cell mass and trophoblast - Gastrula : germ laers ( ectoderm, mesoderm , endoderm) , body cavities (archenteron, coelom), bilateral symmetry - ![](media/image6.png) - Ectoderm : outside brain cells and skin cells , mesoderm : middle all of the ograns , endoderm inside liver bones, muscle, heart , blood cells - Mesoderm: lots of limb development , - Ecto is blue, meso is red and endo is yellow, - - Deuterostome, - Blastopore is going to be your anus because it is formed first , and mouth forms second , - Protostome , mouth forms first - - For frogs, they have lots of yolk and lots of cells at the top , they differentiate it by at the border of the vegetal and animal pole , goes through involition because it turns inside out and you start to have bits going inside, make a hole and you sed yoru cells in to create your three different layers, - - If reptile or bird you ave much flatter surface, do te same thing as frog , make nice ong streak and then you get a nice long streak and cells migrate over the streak to the inside and again , have ecto , endo and meso in middle , get clel so migrate to the top , go in and start to form. - - Gastrulation in mammals - Inner cell mass starts to create amniotic cavity , amniotic sac and amniotic fluid ,. - Called inner cell mass reorganises , - Epiblast -- ectoderm - Hypoblast = endoderm , migae around blastocoel - Inner cell mass becomes flattened - Formulation of the primitive streak , gastrulation pattern from hee is like birds and reptiles , - A cavity opens up , get invagination of blastula, so cells are more or less same , cells migrate into that hole or strea , which form the middle layer and you get the three layers. - - - Tissues development - Ectoderm - Outer layer - Body covering - Neural tissue - Sensory cells - Mesoderm - Middle layer - Gonads - Heart and blood vessels - Nephridia ( kidneys)\ digestive glands - Internal skeleton - Muscles - Endoderm - Inner layer - Lungs - Gut - Gut derivatives (ducts and tubes) - Determination - Fate of protostome cells are determine from onset of cleavage - Deuterostome cells remain totipotent unti later in development ( stem cells) -- indeterminate development - They can become anthing righ up until later in development - Pluripotent -- many opportunities to o and do different things, have potential to become anything so theyre essentially stem cells - Stem cells - Ca become any cells - Fertilised egg is ultimat stem cell - As they start to divide and differentiate they always make a copy of themselves, - Whe they divide , one of the daughter ells is a copy of themselves where the other is often a differentiated cell that will goa nd becoe something else nad stop dividng - Differetation = making different types of cells - In neurons, you ave stem cells that make a copy of a stem cell plus a neuron and that neuron is then fixed, so stem is very powerful as it will keep on enerating a copy of itself , - Embryonic stem cells ae the ones that are inhe fertilised egg that can go on and becoe anything - All cells have the same DNA , when you become a skin cell, you switch on all the DNA parts that are going to make you a skn cell and switch off all the ones that will make you a neuron or a liver cell. - Use of stem cells in research - Transplantation - Diagnosis - Persoanlised medicine - Use of stem clel sin clinic ( patient treatment ) is still controversial and experimental - Portosome and deuttrostome - Cleavage , spiral vs radial - Development , determinate vs indeterminate - Blastopore mouth vs anus - Mesoderm li pof blastopore vs archenteron - Coelom -- schizocoely vs enterocoely - - Coelom development - If cells are touching each other or not , - Cells can trigger different geetic factors , its mechanical structures nad interaction sbetween cells and development hat can sart to trigger these things - Empty space versus a cell occupied space and te cavities in the embryo develop differenty if you are a protstome or a deutrostomes , - - Neurulation - Purpose o for the nervous system - Have primitive streak with all three alyers moving around , - Ectoderm is layer of cells o outside, to turn into brain, you start to divide the cells uwicker in palces alongside a ridge so you end pu with a neural plate which is surrounded by two little ridges , cells continue to divide , ridges get bigger and then closes up and akes a tube, structure underneath called the notochord -- mesoderm structure which secretes factors , so proteins wll cause these cells to start to divide and create the tube. - Tube becomes your brain and spinal cord, - - Forebrain is cortex , part that is really developed, big and folded and complicated , - Mid brain Cell development - Cells can either proliferate-mitosis or udergo apoptosis for cancer cells, tail in embryo , webbed fingers, neurons that haven't made the right connection 50% etc , - Surviving cells develop through a lineage of cell division by a process called differentiation - In deuterostomes, undifferentiated cells that have the capacity to form many different cells are called stem cells - Embryonic stem cells -- cells that make up the blastula are able to become any cell in the fully formed body - After gastrulation -- process of creating three cell layers , each cell can only become a cell in the tissues that the layer will go on to produce- mesodermal cells can still for vast array of cells. TWINS Monozygotic twins - Single egg fertilised by single sperm and at some stage in the first two weeks the developing embryo splits in two , - Two genetically identical babies develop - Can have monozygotic twins tat ahpepsn at different times in development - Depening on when the egg splits will determine hwo you and your twin live together in the uterus - If egg splits relaly early you end up with two separate eggs with two inner cell masses that are very separate , don't contact each other - Splitting happens later, have common corionic sac so outside membrane is shared but each embryo will have own amniotic sac , - Really eally late, embryo is far advanced , it splits off and end up with two embryos s Dizygotic twins - Two separate eggs fertilised by two different sperm , - Dizygotic twins share the same type of genetic relationship as non twin siblings - Fraternal Semi identical twins - Two sperm cells fuse with single egg, - Vey rare because of the calcium block and the inflatable block - Embryos don't usually survive but a few known cases Mirror split twins shared everything : amniotic sac, chorionic sac , in contact with each other in utero. LECTURE The origins and diversity of plant life and fungi DNA code for all life PROTISTS - Any eukaryotic organism that is not an animal land plant or fungus Polyphetic grouping -- of mixed evolutionary origin of several independent groups that evolved frm the last eukaryotic common ancestor - Diversity of protists nclude - Mycetozoa -- slime moulds - Amoeba - Primary lineage -- include red algae, green algae - Chromists -- include brown algae , diatoms - Alveolates -- dinoflagellates - Euglenozoa -- algae Diploidy Haploidy ------------------------------ --------------------------------------------------------------------------------------------------------------------------------------------------------- ---------- Genetic redundancy Contain 2 copies of each chromosome, provides a backup in case one copy of a gene is damaged or defective allowing cel to continue functioning normally Genetic diversity Increased, undergo sexual reproduction , generating genetic diversity within population Ability to undergo meiosis Allows ofr generation of genetic variation thorugh recombination of chromsoosmes during eiosis mutation Greater tolerance to certain recessive mutations more effectively Complexity and ufnctionality Additional genetic material in diploid cells alow for expression of wider range of genes and development of more complex organisms Algae - Protists with characteristics that resemble those of plants - Commonly in aquatic environments 3 patterns of life cycle in alage and plants Haplontic life cycle ( many green algae) - Dominant and photosynthetic phase is the free living gametphyte - Sporophyte generation -- diploid stage is represented by only the one celled zygote which undergoes meiosis - Haploid stage is a dominant part of the cycle - Gametophyte dominates and sporophyte is just fusion of two cells undergoing meiosis and back to haploid stage ![](media/image8.png) Diplohaplontic life cycle ( all bryophytes and pteridophytes ) - Intermediate condition with both gametophyte and sporophyte free living and multicellular but have different dominant phases - Haploid stage and sporophyte stage which tend to be equal - Both gametophyte and sporophyte are multicellular Diplontic life cycle ( brown alage and higher plants) - Dominant and photosynthetic phase is the diploid sporophyte - Gametophytic phase is represented by single celled gametes or a few celled haploid gametophyte - Gametophte is reduced to tiny, small few germ cells - Sporophyte dominates the life cycle Green algae nad origin of land plants Plyla chlorophyta and charophyta Related to land plants. Marine , terrestrial, fresh , Have - Cuticle - Stomata - Reproductive organs , flowers etc Evolution of and plants from gree algae Non vascular to vascular - Plants colonised land about 470 MYA - Earliest plants were small - Confined to wet margins of wetlands and rivers - Plants arose from charophyte green algae - Plants and green algae both have chlorophyll a and b, similar chloroplast structure, cellulose in cell walls, starch as storage material - ![](media/image10.png) Non vascular plantst - Phylum hepatophyta liverworts - Phylum anthocerophyta hornworts - Phylum bryophyta mosses - Vascular system absent - Linin absent - Gametophyte generation dominant Moss life cycle - Unlilke algal ancestors, plants have developed sophisticated organs with distint lasks - Mosses, liverworts and hornworts -- vascular system absent , lignin absent , gametophyte generation dominant. Fern life cycle - Vascular system - Sporophyte generation dominant Conifers life cycle - Gametophytes are very reduced and enclosed in spoorphytic tissue - Pollen grains are produced in male cones and are transported by wind to the micropyle of the ovule in the female cones - Fertilised ovule develops into seed - Female concerns will produce flower - Male cones produce pollen FLOWERS Dramatically altered earths biota and ecosystems Earliest angiosperm fossil was found 130 MYA Angiosperms dominnat stage is the sporophyte Monocotyledon diverged 140MYA. Consists of 77 families Evolution of flowering plants lead to massive expansion in mbiodiversity - Bees, butterfes, bugs etc - Provided whole source of food - Help with dispersing pollen - Higher mammals , reptiles Move to land - Had to obtain nutrients frm soil - Uptake water - Transport water and nutrients within the plant - Prevent dessication - Prevent UV damage - Structural support -- lignin and wood - Dessication tolerant dispersal units - Pollen protecting sper and seeds which protect the embryo Vascular system : transport of nutrients , lignin for support - Phloem and xylem -- sugars, water and mineral ion transport - Lignin provides rigidity in xylem and fibers -- enables large, land based plant bodies Pollens and seeds - Protect and aid in the dispersal of plant gametes and embryos - Seeds important evolutionary advance providing for a domrnat stage in development - Gymnosperms ovules are exposed directly to pollen at the time of pollination which is then dispersed by wind, in angiosperms ovules are enclosed within an ovary , pollen tube grows frm stigma to ovule - Pollen of gymnosperms is usually disseminated by wind and occasionally by insects , most angiosperms the polleen is transported by insects and other animals - Flowers and fruits found only in angiosperms and account for the extensive colonisation of terrestrial environments by flower plants Seeds - Wide range of different types of seeds and their capacity to disperse and survive for long periods of time - Some seeds can survive up to decades - Coconut tree seeds weigh up to 20kg , take 7 years for the fruit to ripen, 7 to 10 years for germination Stomata : controlling gas exchange and water loss - Present in hornworts, mosses, fossil plants and vascular plants - Control over water loss expanded the range of land plants South west of Australia is hotspot for biodiversity - Centre for plant diversity - 8,000 plant taxa - Ancient andscape, very infertile soil - Gently undulating landscape with exception of striling range - Ancient flora with many old lineages - Exceptional species diversity - Large number of threatened plants and have high number of plant species - High endemisms - Significant proportion of naturally rare plants with geographically restricted range - Many species have naturally fragmented disjunct distributions - 3,366 rare ( nearly 30%) WAs flora - 12,619 native species - 3,254 rare and poorly known - 429 listed as threatened flora - 160 critically endangered - 1,194 recognised but not published as it lacks suitable guides to their identification , undercollected or rare - Estimate atleast 10% remain unknwon - 81 new taxa described in 2018 - ![](media/image12.png) FUNGAL DIVERSITY Fungi - Occupy entire biosphere - Land, sea, water and air - 72,000 named species but only 5% of what we suspect estimates suggest 1.5 million - Mushrooms , puffballs are only temporary fruiting bodies - Fungi eukaryotic heterotrophs with external digestion, rigid cell walls that reproduce by spores - Mycelium -- body of the fungus - Hyphae -- filamentous, microscopic, chitinous tubes - Chiti in cell wall, haploid nucleis in non sexual cells -- vegetative Closest relative is the animalia kingdom Animals have no chitin in cell membrane, have diploid nuclei in non sexual cells -- somatic Fungal nutrition - Fungi digest nearly any form of organic carbon - Heterotrophic -- use glucose as source of carbon - Saprophytic- decomposers, release enzymes onto substrate , absorbs nutrients - Parasitic -- highly specialised - Carnivorous -- derives some or most of its nutrients frm trapping and eating microscopic or other animals - Huge range of getting different nutrition Hyphal tip growth and absorption of nutrients - Secrete enzymes , absorb whatever material you come into contact with and it receives its nutrition - Slime moulds also do this but are not in the fungi group - Fungi are nutrient recyclers -- saprophytes - Some 'recyycle' organisms that are not dead yet -- parasites - Nearly all plant eating animals use fungi and or bacteria to digest plant material - Many can digest lignin - Grow by extending the tip of the chitinous tube and dissolving gsusbtrate - Chitin : strong , light and structural Phylogeny of the major groups of fungi - Microsporidia - Chytridiomycota -- water moulds - Zygomycota ! -- moulds - AM fungi - Ascomycota ! - Basidiomycota ! Fungal reprodtcion -- spores - Asexual and sexual spores - Highy resistance and produced in billions - Mostly terrestrial and occupy a wide range of habitats including soil, plants and anials - Most species live off decaying organic material, some form symbiotic relationshisps with plants , soe are parasites of plants and animals - Zygomycetes include the familiar bread mold which rapidly propagates on the surface of breads and fruits - Have dominant classic gametophyte life cycle -- two different gametophyte which are compatible, fuse and get high full bridge and form a zygospore -- which is the actual zygote , its diploid and undergoes meiosis to produce more spores to generate idffernet types of mycelia. Two largest group sof fungi Basidiomycota and ascomycota Basidiomycota - Spores formed externally on special cells called basidia Ascomycota - Spores produced internally in sacs - Used in genetic studies due to its colour forms - Yeast - 60,000 species - Heterokaryon hyphase -- two nuclei in a single cell , not diploid - Pores septa - Asexual conidia - Sexua lascospores Life cycle - Predominantly haploid - Have haploid male and female strains mycelium in hyphase - One will produce an anthea ad other will produce male and female parts , get fusion between them - Get formation of heterokaryon hyphase that produces the fruiting body of asomycota - 2 different hyphase, one has heterokaryotic hyphae - Other hyphase has single nucleus and that fruit body which produces asi , undergoes meiosis and creates the asco spores , Yeasts - Beer brewing - Wine making -- natural yeast live on the surface of grape skin - Bread making -- like beer brewing but alcohol is cooked off Basidiomycota - Mushrooms , toadstools, rust - 25,000 species Characteristics - Dikaryon hyphae - Septa with complex spores - Asexual conidia - Sexually derived basidiospores - All sorts of different types of fruiting bodies produced by basidiomycetes Life cycle - Have two nuclei and the basidium - Fuse to give single diploid nucleius that dnergoes meiosis and you produce basidiospores and produce two different types of haploid hyphae in the mycelium Uses - Eating and drinking fungi - Soy sauce - Bean curd - Camembert and brie Fungal diseases - Athleets foot - Ring worm - 400 fungal pathogens both internally and externally - Allergens frm spores , Hallucinogenic fungi - Magic mushrooms - Yellow ops and bue meanies - Fungi can produce extremely toxic ocmpounds , very similar to LSD Poisonous fungi - 90% of fungi deaths worldwide have been caused by the death cap 'amanita mushrooms - Toxic effect : inhibit production of specific proteins within liver and kidney cells , without these proteins, cells cease to function and die - Symbols : after ingestion, 5 -24 hrs nausea, vomiting , diarrhoea - Severe liver damage and kidney failure often result in coma nad death Fungal mutalisms - Fungi form interdependent relationships with other organisms - Usually photosynthetic organisms like land plants and alga - Lichens, - Mycorrizas - Carnivorous plants Lichens - 18,000 species - Biocrust -- from a livin skin at the osil surcace, comination of lichens, cyanobacteria, algae nad mosses, critical aprt of maintnaing biodiversity , mycorrihizas - Fungus root -- nutrient brigde between soil and plnat roots - Carbs for fungus , P, Zn, water , N for plant - Infect 90% of all land plants - Very fine hyphae -- fungal filaments which have greater surface area and can penetrate smaller pores , - Possibly the first roots - Present I all land plant lineages - Increase field growth. Survival, protetction against pathogens , reduce fertiliser ues , and stunting. - , 3 major types arbuscular important for agriculture , 200,000 species, assist in nutriet abrosption ectomycorriza : sheathing mycorriza , associate outside the root itself, mostly mushrooms , mainly on temperate trees , 10,000 species orchid mycorriza -- case of extreme fungal dependency , need it to geerminae the orchid seed , most cases, carnivorous plants - Little dross around edge of leaves, insect gets stuck and they get digested - Little dross is fungus which helps in digesting insect Lecture 7.1 Photosynthesis, leaf structure and function Key learning outcimes - Understand the concept of leaves as 'green machines' that produce sugar and export this photosynthate to feed the plant body - Gain an understanding of leaf structure as related to leaf function -- comparison of terrestrial and aquatic leaves - Understand 3 different modes of photosynthesis What are the main functions of a leaf Photosynthesis = light capture and assimilation of CO2 , - Requires light absorbing pigments and several enzumes to allow light capture and CO2 assimilation - Also requires a system that allows diffusoion of CO2 from the atmosphere to chloroplasts ( the sites of CO2 fixation) Location of a chloroplast within a plant Thylakoid membranes contain protein complexes for - The light harvesting system -chlorophyll - The electron transport system - The ATP synthesis system - The absorption of photons of rthe transport of electrons across the membrane Chlorophyll - Major light harvesting pigments - Chlorophyll a absorbs red and chlorophyll b absorbs blue , Overview of reactions of photosynthesis 6CO2 +12H20+photons -\> C6H12O6+O6 Light reactions in the thylakoids use light eergy to oxidise water, produce oxugena nd generate ATP and NADPH Calvin benson cycle is a light independent -- dosent need light and occurs in the stroma , and only needs CO2 to create sugar , RUBISCO Enzyme that fixes CO2 Catalyses a reaction of 5C receptor molecules +CO2 -\> 2X 3C compound Additional reactions then use the 2 X 3C compounds to make sugar ![A diagram of photosynthesis Description automatically generated](media/image14.png) 3C plants are called that because they make 3 cabron compounds The one w the light sectin is in the thylakoid membranes ATP to sugar is in the stroma The hwole process is in the thylakoid membrane You can tell it's a eudicot with the VBSC and the mesophyll cells ![](media/image16.png) Cuticle on the epidermal cells of a leaf , protective layer around the reproductive organs like seed coats that reduce water loss and the risk of dessication. these traits are the first characteristics important in the transition of plants frm water to land, restricts water loss , Stomata , allows diffucion of CO2 frm the atmosphere to the chloroplast , stomata close when water availability is low. aquatic plants don't need this. when there is a lot of water they swell and pull apart have fibres to have rigidity. They have stoma ![A cross section of a plant Description automatically generated](media/image18.png) Parallel lines- monocot , no palisade mesophyll C3 plants 83% of plants It's the most common metabolic pathway , converts CO2 and ribulose biphosphate into two molecules of phosphoglylerate (PGA) within the chorolast CO2+H20+RuB \_\> phosphoglycerate C4 plants Bundlesheath cells have chloroplasts , Don't have classic structure with palisade and spongy mesophyll Anatomy and biochemical specialisation enbales photosynthesis to operate at a lower internal CO2 in the bulk tissue - CO2 initially fixed by the enzyme PEP to malate in the mesophyll cells - Oxaloacetate is then transported into the bundle sheath cells where the chloroplast are concentrated and then decarboxylated to release CO2 , - High CO2 at site of RUBISCO - Spatial arrangement that helps cocncentrate the CO2 really effectively so that less energy is involved and less water is lost CAM plants - Family of succulent species in which CAM photosynthesis was frst discovered - Crassulacean Acid Metabolism - They separate the process by concentrating CO2 snad then fixing CO2 by the timeof the day Once sun is up , they close stoamata as they don't need more CO2 , go to work converting that malate back to CO2 , going thorugh calvin cycle to produce our sugars , ![](media/image20.png)tend to be in arid environments , man epiphytes are rgowing on them. Aquatic and marine plants - Very thin to absent cuticle - Chloroplasts most abundant in outer surfaces -- epidermis , - Slow diffusion of gases in water ie slow movement across the 'diffusive boundary layer' is a key challenge - Their challenge is to get CO2 in - Have no stomata - Take up CO2 frm surrounding water - Some species also acces bicarbonate - pH in water influences CO2 avialability - seawater has pH of mildly strong to quite strong alakaline between 7 and 9 ![](media/image22.png) Lecture 7.2 plant water relationships Key learning outcomes - broad understanding of the concepts of plant water relationships called plant water relations - know the differences between water potential , osmotic potential and turgor pressure - familiarity with root pressure and guttation - understand the basics of water transport in the xylem, - structure and capillary forces in xylem walls - negative xylem pressures like suction tensions - xylem cavitations plant water relations how plants control the hydration of their cells including - acquisition of water from soil using uptake - water transport within plants from roots to leaves - water loss by evaporation from leaves ( transpiration) to atmosphere - tugor: the pressure that the water places on the cell wall - stomata open by guard cells taking up ions and water flows , which increases turgor in the two guard cells and these cells 'push apart' owing to their structure - stomata first appeared atleast 400 million years ago turgid : water sufficient and cell wall is pushing out flaccid cell is when cell walls are shrinking how do plant water relations work hydration of cells generate an internal hydrostatic pressure (turgor) that drives cell expansion for organ growth hydrostatic pressure / turgor pressure isgenerated in plant cells because water moves by osmosis across semipermeable membranes , turgor pressure is central to nearly all plant function -- plants are hydraulic machines gymnosperms don't have vessels in tehir xylem , they only have tracheids series of pipes that are conncected called xylem vessesls in angiosperms, water moves frm bottom of the plant to the top through connected vessels, changes in the turgor pressure frm each vessel that causes the water to be pushed up. sugars are used to moderate the solute concentration in the water in the xylem to create osmotic potential. turgor also helps plants move, reversible movement of water across cell membranes cause tissues to swell or shrink. pulvinus= an enlarged section at the base of a leaf stalk in some plants which change the leaf angle sits relative to the plant so it can optimise directional light capture stomata opening stomata open by guard cells taking up ions and water follows, which increases turgor in the two guard cells and these cells 'push apart' owing to their structure. the more turbulence there is at the surface, the greater evaporative loss, the greater the transport of water from plant into atmosphere= transpiration evaporatin is driven by the gradient in humidity resistances to diffusion of water molecuels in the gas phase within leaves -- depends on intercellular space pathway resistance across stomata -- depending on stomal aperture : cuticle high resistance diffusive boundary layer to the drier air ![A screenshot of a cell phone Description automatically generated](media/image24.png) High conductance is when stomata is easy to be opened while los conductance means that stomata has to work a lot harder to be opened up Transpiration - leaves can transpire several times their own volume of water each day dependent upon the inflow of water drawn up the plant frm soil - this flow of water up the plant occurs in the xylem and is called the transpiration stream - hairy the roots are because increase surface area for water uptake and nutrient uptake - A screenshot of a computer screen Description automatically generated Water that have solutes has a negative water potential compared with that of pure water Water will move spontaneously from a region of less negative to adjacent region of more negative , Water can be pushed up , so the difference in osmotic potential is balanced by that in the pressure potential Water potential in plants is what drives water movement Two components: osmotic and hydrostatic pressure potential Pressure potential is also known as turgor ![](media/image26.png) More negative the water potential the more that plant has to work to get water Water movement across semipermeable membranes is driven by gradients in water potential ![A diagram of cell water Description automatically generated](media/image28.png) Rigid cell wall stops it from bursting Root pressure = the hydrostatic pressure generated in the roots that helps drive water and ions from the soil in upwards directions into the plants vascular tissue ( xylem) Process 1. Roots take up ions like potassium which are pumped into the xylem 2. Creates a concentration gradient 3. Osmostically draws in water from the soil 4. Water is pushed up the stem which pulls I more water Due to root pressure , water can be pushed up to most several meters -- mainly when water demand is low Slow in comparison with transpiration Root pressure can give rise to' guttaion' when transpiration rates are very low ( over hydration) Guttation from hydathodes( modified stomata) -- the secretion of droplets of water from the pores of plants Generally solute concentrations are much too low to push the xylem sap beyond several meters at most so water get sto the top of the tree by gradients in hydrostatic pressure Rather than just one whole thing being pushed up by the pipes through turgor pressure its looking at segments in the xylem / pipelines pushed up into the next section into the next section - Root pressure can help maintain the water volume for some parts of the water column but not full water column a - Low pressure at the bottom - Flows of water are driven by gradients ( in pressure or in water potential ) , constrained by resistance in the pathway - Resistances to water flow vary markedly in the soil, into and across the root s( radial) , in the xylem of root , stem , petiole, leaf vein and through leaf tissues to the evaporating surfaces within the leaf - These are liquid phase flows prior to evaporation Pore space and charge of materials in soil can chanage the difficulty of moving through soil for water Water gets to top through - low water potential of air drives water loss from leaves constant evaporation - Loss of water from the leaves pulls ( generates a suction tension) in the xylem - This suction tension pulls water up the stem which in turn also sucks water from soil into roots - The evaporation pulls water How can we account for the negative xylem water potential = suction tension - Air inside leaf is almost saturated with water vapour 98% Relative Humidity - Air outside leaf has lower RH and very negative water potential - Large gradient for water to move leaf thorugh air - Water will move along that gradient from leaf to air Water molecules that leave the stomatal cavities to the atmosphere are relaced by molecules that leave the xylem through capillaries in the xylem walls Negative water potential ( suction tension) due to capillary forces : water is tightly held in the capillaries in xylem wall Capillary forces are responsible for suction tension or negative pressure in the xylem Water molecules are held together by hydrogen bbonds, so the tensile strength of water is very large Water column in xylem remains intact and dosent break A matter of cohesive forces ( water to water) and adhesive forces ( water to xylem walls) See a plant , look at water potential of 0.1mP , thin about pressusre potential and then solute potential , what is our pressure potential positive pressure is 0.8 , solute pressure = -1 now is whatever so our net water potential is 0.2 Higher up the stem we have more pressure potential , some solute potential. so net value is -1.1. atmosphere is -30 so fairly slight graidnet thorugh the tree Using the concept of water potential we can understand water transport up the stem of a tree - Negative water potential of air esp when we have high VPD - Negative water potentials of air in stomatal cavities - Negative xylem water potentials ( Suctoin tensions) due to d=binding of water in cpaillaries in wall - Tensile strength ( hydrogen bonding) of water ( water column intact ) Really tall trees need to be in high rainfall areas because it has to pump water all the way up the stem and out into canopy Air bubbles are a real risk for plants that live in dry environmentsas they can block parts of the stem , whichis why plats wilt because they cant move water or recover because the stems are blocked A diagram of a plant Description automatically generated Xylem cavitation = embolism : the breaking of a water volumn -- can no longer transport water ![](media/image30.png) Desert planst transport their water into different parts of their wood instead of being hydraculically necessarily efficiently with lots of big open pipes that pool, water so they sacrifice bits of their structure so that more water can be dispersed torughout it / A screenshot of a cell water relation Description automatically generated NEW LECTURE Plant nutrient and water uptake Key learning outcomes - Essential mineral elements required by plants - Revision on basic structure of rots -- monocots vs eudicots - Nutrient uptake by roots linked to water can require metabolic energy as ions like phosphate, nitrate are taken pu against an electrochemical potential gradient - Different nutrient acquisition strategies of plants and how these are represented in asutralia flora - Association between adaptive mechanisms and soil fertility particularly Nitrogen and phosphate What do plants need to grow, survive and reproduce - Adequate light. - Right temperature - Adequate oxyegen - Water - Carbon - Nutriets like nitrogen and phsphorous - Photosynthesis Rubisco is an enzyme , it's a protein, it contains nitrogen because etheir AA are organic nitrogen Phosphorous is also in the membranes as phospholipids ![A diagram of a plant Description automatically generated](media/image32.png) Potassium: often exchanged across memebranes in exchange for something else, used to regulate that solute concentration that affects solute potential and water potential Unless your aquatic plant, might absorb nutrients directly frm water , as well as from the sediment Nitrogen is in large quantity in the atmosphere but not a lot from soil and roots which the nitrogen fixing bacteria does Elem

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