Plants and Animals Have Specialised Structures to Obtain Nutrients from Their Environment

Patterns In Nature Part 3

Plants and animals have specialised structures to obtain nutrients from their environment

• identify some examples that demonstrate the structural and functional relationships between cells, tissues, organs and organ systems in multicellular organisms

-Inmulticellularorganisms,differentcellscanbecomespecialisedto performdifferentfunctions.

-Multicellularorganismsare madeup ofmanycells.

-CELLS arethe smallestunit of life. Theyperform specificfunctions:

• E.g.musclecell-its job is to contract or relax

-TISSUESaregroupsofcellswithsimilarfunctions.Theyperformfunctionsasagroup ofcells:

• E.g.muscle tissue -madeup ofmuscle cells, job is to contract or relax

-ORGANSaremadeup ofgroups of tissues that function as a whole:

• E.g. the stomach-made ofmuscletissues, is moves to churnfood

-ORGANSYSTEMSaregroupsoforgansthatfunctiontogetherasacoordinatedsystem to perform a roleforthe body

• E.g.digestive system -madeup oforgans such asthe stomach

• distinguish between autotrophs and heterotrophs in terms of nutrient requirements

-Autotrophicmeans‘self-feeding’.Autotrophs areorganisms thatmaketheirown food through photosynthesis:

• Nutrientrequirements:Autotrophs,suchasplants,requirethesubstancesnecessaryforphotosynthesis.Thesearewater,carbondioxideandsunlight.Theyalsoneed oxygen and sugarsfor respiration

-Heterotrophsareorganisms thatconsume otherorganismsfornutrition:

• Nutrientrequirements:Heterotrophsrequireotherorganismstofeedon,suchashowherbivoreseatplants,andcarnivoreseatmeat.Theyalsoneedoxygenforrespirationandwaterforlife.

-identify the materials required for photosynthesis and its role in ecosystems

-Photosynthesis is the process bywhich plants create glucose

-Thissynthesisoforganiccompoundsfrominorganiccompoundsisaprocessalllivingthings ultimatelydepend on.

-Plantsmakefoodthroughphotosynthesis,herbivoreseatplants,carnivoreseatherbivores, and the foodchaincontinues. However, theyallbegin with plants

-Thematerialsneeded forphotosynthesis are water,CO2, andchlorophyll

• identify the general word equation for photosynthesis and outline this as a summary of a chain of biochemical reactions

-Thegeneralwordequation forphotosynthesis is:

Carbon dioxide+ WaterSUNLIGHTAndCHLOROPHYLLSugarandOxygen

-Thechemicalequation for photosynthesis is:

6CO2+ 12H2O C6H12O6+ 6O2+6H2O

Photosynthesis is thought to occur in two stages:

Light Reactions of Photosynthesis:

-Onlythis stage requiressunlight

-Light absorbed bychloroplasts is used to split watermolecules

-This process is calledphotolysis

-In this process, thewater molecule is split into oxygenandhydrogen

-This processoccurs onthe thylakoids ofchloroplasts

Light-Independent Reactions of Photosynthesis:

-Also called the carbon-fixation stage

-Hydrogenreleasedfromthefirstreactionisjoinedwithcarbondioxidetoformsugars

-This processrequires energy

• explain the relationship between the organisation of the structures used to obtain water and minerals in a range of plants and the need to increase the surface area available for absorption

Obtainingwaterand minerals:

-Inaquaticenvironments,waterandmineralsareabsorbedacrossthewholesurface of theplants

-However,forterrestrial(land)plants,waterandmineralsareobtainedthroughroot systemsRootsystemsmusthaveaverylargesurfaceareatoabsorbenoughnutrientsforthe wholeplant

-Theyachieve this through havinga branchingstructureandmanyroot hairs

-Therootsystemcanalso be used to anchor theplant

-Manydifferenttypes of root systems exist

Differenttypes of roots used to absorbnutrients are:

-TAPROOTS:Thesetypesofrootsystemshaveonemainroot,calledthetaproot,fromwhichsiderootscomeoutfrom.Taprootsmanypenetratedeeplyintothesoil.Sometimesthetaprootsactasstorageorgansandswell up, suchascarrots.

-FIBROUSROOTS:Theserootsystemsformnetworksofrootsclosetothesoilsurface.Theycanspreadoutwidelytosupporttheplant,andprovide alarge surfacearea forabsorption of mineral ions andwater

-MYCORRHIZA:Thisiswheretherootsystemisassociatedwithfungiinasymbioticrelationship.Thefungiprovidestheplantswithadditionalmineralnutrientsandtheplantprovidescarbonbasedproductsforthefungi

-AERIALROOTS:Inareaslikewaterloggedestuariesorswamps,plantsproducerootsthatgrowabovetheground.Theserootshelpwithgasexchange

External Root Structure:

-Therootsystem of aplant is usuallybelow theground

-Roots do not photosynthesise,and do not haveleaves or buds

-Thegrowingpoints of roots are protectedbyrootcaps

-Asrootsgrowthroughoutthesoiltheybranchoutandprovidealargesurface area for absorption aswellas ananchorfor the plant

-Most of theabsorptionoccurs in the root hairs of the root

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Internal Root Structure:

-Thebasicrootstructureismadeupofthethreeparts:theepidermis,thecortexand the vascular tissue

-Epidermis:Theouterlayeroftheroot.Itlacksacuticle.Inyoungroots,the epidermis is coveredwith a slimycoatingor sheathcalledmucigel

-Cortex:Thecortexisinbetweentheepidermisandthevasculartissue.Itacts as astorage areafor excessmaterials,andhasairspaces for gasflow

-VascularTissue:Inroots,itformsacylinderinthecentre.Itismadeofxylemand phloem vessels.It transports waterandnutrients

-VasculartissueInrootsthevasculartissueformsacylinderinthecentre.Itconsistsofxylemandphloem,andissome-timescalledthestele.

• explain the relationship between the shape of leaves, the distribution of tissues in them and their role

Obtainingsunlightand carbondioxide:

-Thespecialisedleafstructureoftheplantusedforobtaininglightandcarbondioxide isthe leaf

-Most of thephotosynthesis of plants occurs in leaves

-Thelamina is thebladeof theleaf

-Thepetiole is the part that attaches it to thestem

ExternalLeafStructure:

-Arrangement:Leavesareusuallyarrangedalongthestemsinawaythatexposesthemtothemaximumamountofsunlight.Theyareusuallypositioned so thatsunlightstrikes the upperpart of theleaf.

-Shape:Most leaves are broad,thinandflat. This givesthemalargesurfaceareafor thecaptureofsunlightandgasexchangeneededforphotosynthesis and respiration.

InternalLeafStructure:

-Cuticle:Thisisawaxylayeroverthesurfaceoftheleaf.Itiswaterproofandprovidesshapeandprotection.Itplaysanimportantpartinreducingwaterloss in terrestrial plants

-Epidermis:Itisasingleprotectivelayerofcellsontheupperandlowerside of leaves.It is transparent to allow light to pass through.

-Stomates:Theseareporesintheleafthatcanopenandclose.Whenopen,theyallowgasexchange,but this results in waterloss.

-Mesophyll:Mesophyllarethecellsinthemiddleofthecell,inbetweenthe upperepidermis and lower epidermis. There aretwo types:

• PalisadeMesophyll:Theyareregularlyarranged,elongatedandpackedwithchloroplasts.Mostofthephotosynthesisoccursinthesecells.
• SpongyMesophyll:Situatedunderthepalisade,butabovethelowerepidermis.Containslesschloroplasts,andarerandomlyarrangedwithlarge airspaces toallowgasexchange.

-Veins:Veinsaretubesofvasculartissueinplants.They formabranchingnetwork in the leaves, providingstructureand shape. Vasculartissue:

• XYLEM:Transportswaterandmineralsfrom roots to leaves
• PHLOEM: Transports products of photosynthesisto the rest of plant

• describe the role of teeth in increasing the surface area of complex foods for exposure to digestive chemicals

-Animals areheterotrophic; theyget nourishment from the external environment

-Thedigestivesystemisthesystemresponsibleforbreakingdownfoodtoasizewheretheycanbeusedbycells

-Therearetwo parts of digestion:

• MechanicalDigestion:

-This involves breakingfood down through mechanical means.

-Theteeth arethe most importantmeans of mechanicaldigestion.

-Theroleofteethistobreakfooddownintosmallerpiecestoincreasethesurface area of the food.

-Thegreaterthesurfacearea,thebetterthedigestivechemicalscanactonthe food.

-Thestomach is also involved withmechanicaldigestion.

• Chemicaldigestion:

-This involves the useof enzymes to chemicallybreakfood down.

-Amylases- enzyme thatacts on carbohydrates.

-Proteases-enzyme that acts on proteins.

-Lipases - enzyme that acts on lipids.

• explain the relationship between the length and overall complexity of digestive systems of a vertebrate herbivore and a vertebrate carnivore with respect to:

–the chemical composition of their diet

–the functions of the structures involved

Herbivores:

-Themain component ofa herbivore’sdiet is plantmaterial

-Most of themass ofplant material is madeup ofcellulose

-Theyhaveflatteeth togrind the fibrous plant material

-Plant material is difficult to breakdowncomparedtoanimalmaterial

-Herbivores usethe helpofmicro-organisms to helpdigest thecellulose

-This digestioncan occurin two places:

1. FORE-GUTFERMENTERS:Thistypeofherbivore(e.g.cows)digeststheirfoodin a chamberbefore the stomachcalledtherumen

1. HIND-GUTFERMENTERS:Thistypeofherbivore(e.g.horses)digestsits food in a chamberafter thesmall intestine called thecaecum.

-Compared to meat,plantmaterial is low in energy

-Plants alsotake longer and is harder to digestthanmeat

-This meansthatherbivoreshave to constantlyeatto survive

-Thedigestivesystemsofherbivoresarealotlargerandlongerthanthatofcarnivores. This is because plants take longer to digest

Carnivores:

-Themain component oftheir diet is meat

-Meat is high in energy, and is relativelyeasyto digest

-Thismeansthatthedigestivesystemsofcarnivoresareshortcomparedtoherbivores and also have to specialisedorgans likethe caecum or rumen

-Theyhaveveryshortlargeintestines,asthemeathasalreadybeenabsorbedin thesmall intestine

• plan, choose equipment or resources and perform first-hand investigations to gather information and use available evidence to demonstrate the need for chlorophyll and light in photosynthesis

• perform a first-hand investigation to demonstrate the relationship between surface area and rate of reaction

• identify data sources, gather, process, analyse and present information from secondary sources and use available evidence to compare the digestive systems of mammals, including a grazing herbivore, carnivore and a predominantly nectar feeding animal

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