Biology - An Illustrated Guide to Science (794127), страница 33
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The smallest arethe auditory ossicles in the middle ear.● The skeleton provides places to attachmuscles, acts as a mineral store,protects key body organs, andmanufacturers certain types of bloodcells.●claviclescapula(shoulder blade)sternumribhumerusvertebraradiuspelvisulnasacrumcarpalsmetacarpalsphalangesThe axial skeletonThe axial skeleton consists of thehead, spine, and associated structureslike the ribs and shoulder blades.● The axial skeleton protects key bodyorgans (the brain, spinal cord, heart,and lungs).●The pentadactyl limbsThe limbs in humans follow thestandard pentadactyl pattern.● A single bone at the top of the limblinks to two bones below.● A set of five bones form the nextsection leading in turn to five digitsterminating in five phalanges.● The presence of the pen tadactyl lim bin many animals is evidence fordescent from a common ancestor—a key feature of evolutionary theory.●femurpatellatibiatarsalmetatarsalsphalanges© Diagram Visual Information Ltd.fibula190HUMAN BIOLOGYKey wordscartilaginousjointsynovial jointLocomotion: jointsJointsBall and socket joint: hip jointcapsulepelvisligamentTypes of jointA joint is formed where two or morebones link together.
There are threebasic types of joint.● Fixed joints in the cranium of the skullallow no movement at all. The bonesare fused together.● Cartilagin ou s join ts have a cartilageconnection between bones and allowsome movement. The joint betweenthe two halves of the pelvis is acartilaginous joint. In pregnancy thiscartilage is softened by hormoneaction so that during childbirth thepelvis has enough flexibility tofacilitate passage of the baby’s head.● Syn ovial join ts allow a much widerrange of movement and can be furtherclassified into ball and socket joints,hinge joints, and others based on theirarc of movement.●Synovial jointsBall and socket joints allow movementin two planes.● The hip joint is a ball and socket joint.The ball at the head of the femur fitsinto a boney socket in the pelvis.Ligaments hold the bones together.A synovial membrane lines the insideof the joint and secretes a lubricatingfluid called synovial fluid.
The parts ofthe bone that move against each otherare covered with a smooth tough formof cartilage. The loose fibrous capsulepermits the hip joint to have a largerange of movement.● The knee joint is an example of ahinge joint. The bones are shaped toallow movement in only one plane.● The knee is made up of the lower endof the femur, which rotates on theupper end of the tibia, and the patella,which slides in a groove on the end ofthe femur. The joint is bathed in aviscous fluid that is contained insidethe synovial membrane. Cartilageserves to cushion the knee and helpsit absorb shock during motion.ligamentsynovialmembranecartilagesynovialfluidcapsulefemurHinge joint: knee jointmusclefemurtendonSkeletonpatella(knee cap)© Diagram Visual Information Ltd.●cartilagecapsulesynovial fluidsynovialmembranetibiahip joint(ball andsocketjoint)knee joint(hinge joint)191Terrestrial biomesECOLOGYKey wordsBiomesRain forestThis biome is found in tropical regions withhigh rainfall close to the equator.
It consistschiefly of tall trees that form a dense canopyhigh above the ground. Shrubs and smallerplants live on trunks and branches in thecanopy, while the forest floor supportsmainly fungi and invertebrates that live offdecomposing vegetation.DesertDesert is found in regions where rainfall isbelow 10 inches (25 cm) per year. Perennialplants such as cacti, yuccas, and agavesare resistant to drought, while quick-growingannuals appear and disappear with therains.GrasslandThis biome is typical of continental interiorsand is dominated by grasses, which survivethe dry season by means of undergroundstems (rhizomes). Herbivorous animals,such as antelope, zebra, and cattle, arecommon here.biomeDeciduous forestDeciduous forest is found in temperateregions with evenly distributed rainfall, andis dominated by deciduous hardwood treessuch as oak, beech, and maple. The forestfloor often supports shrubs and groundplants.TaigaTaiga is typical of cool regions in highlatitudes and mountains with a short growingseason.
It consists almost entirely ofevergreen coniferous forest, with sparseherbs and shrubs.TundraTundra is found especially encircling theNorth Pole, and also on high mountains(alpine tundra), where temperatures are lowand the growing season is short. In Arcticregions the ground is permanently frozen(permafrost) below the surface layer. Hardyplants such as mosses, sedges, and lichensform the sparse vegetation.Distribution of biomesBiomesA biome is a large community of livingorganisms that are adapted to aparticular climate and soil conditions.Biomes are characterized by theirdominant vegetation, for example,grasses or tropical trees. Biomes maystretch across entire continents andgradually merge with adjoiningbiomes.● The dominant factor controllingestablishment of a biome type appearsto be incoming sunlight, as biomes arebroadly parallel bands aligned with theequator.●Biome typesKeyrain forestdeciduous forestdeserttaigagrasslandtundradepends onhigh solar radiation andrainfall.
It is a complexsystem with manyspecies.● Desert has similarsunlight input but hasvery low rainfall: below10 inches (25 cm) peryear. This leads to avery impoverishedvegetation cover.● Grasslands predominatefurther away from theequator.● Still further away areforests, initially thedeciduous forest, withtrees that lose theirleaves in the winter.Nearer the poles areconiferous forests, withtrees that can survive in ground that isfrozen solid for at least part of theyear. These forests form the taiga. Themost extreme biome is tundra.
Thishas very limited vegetation cover, notrees, and is sometimes referred to asa “cold desert.”© Diagram Visual Information Ltd.● Rainforest192ECOLOGYCarbon cycleKey wordsGlobal warmingcarbon cyclephotosynthesisrespirationIn recent times, humans have been burning large quantities of fossil fuels, which has ledto a rising concentration of carbon dioxide in the atmosphere.● This is intensifying the “greenhouse effect,” whereby carbon dioxide and other gases in theEarth’s atmosphere act like the glass in a greenhouse, trapping heat near the Earth’s surface.● Consequently the average temperature at the Earth’s surface is gradually rising—thephenomenon called global warming—with potentially disastrous consequences.
These mayinclude rising sea levels, disrupted weather patterns, devastation of farming and naturalecosystems, and mass extinction of organisms.●Carbon cycleCarbon, the fourth most abundantelement in the Universe, is thebuilding block of life. It is the elementcentral to all organic substances, fromfossil fuels to DNA.● The total amount of carbon on planetEarth is fixed. The same carbon atomsin the atmosphere and in your bodyhave been used in countless othermolecules since the Earth began.
TheCarbon cycle is the complex set ofprocesses through which all carbonatoms rotate.● Carbon exists in Earth'satmosphere primarilyas the gas carbondioxide (1). Throughphotosynthesis plantsfix carbon dioxidefrom the atmosphereinto sugars, which theyneed to grow (2).● Animals eat the plantsand use the carbon fortheir own maintenanceand growth (3).Animals return carbondioxide into the airthrough respiration(4) and when they die(7), since carbon isreturned to the soilduring decomposition.● Plants and animals decay and, overthe course of millions of years, createfossil fuels—coal, oil, natural gas (5).● Burning fossil fuels returns the carbonin these fuels to the atmosphere (6).© Diagram Visual Information Ltd.●Carbon cycle12643751234Atmospheric pool of carbon dioxidePlants take up carbon dioxide forphotosynthesisAnimals eat plantsCarbon dioxide released by respiration567Fossil fuelsCarbon dioxide released by combustionDeath of organisms and decay by bacteria193Nitrogen cycleECOLOGYKey wordsNitrogen cycledecomposernitrogen cycleImportance of nitrogen1● Allliving things need nitrogen tobuild protein.
However, mostorganisms cannot use nitrogen gasand nitrates (the dominant form ofthe element in the soil) arepoisonous to animals.● Four processes cycle nitrogenthrough the biosphere: nitrogenfixation, decay, nitrification, anddenitrification.12Nitrogen fixationPlants must secure theirnitrogen in “fixed” form, assoluble nitrates. Nitrogen canbe fixed in three ways.● Lightening helps oxygen and nitrogento react to form nitrogen oxides,which dissolve in rainwater tobecome nitrates in the soil (1,12)● Nitrogen fixing bacteria in theroot nodules of legumes andin the soil can convertnitrogen into usablecompounds (2, 4).● Fertilizers can contribute useablenitrogen compounds to the soil (3).● Plants take in soluable nitratesthrough their roots and use them tobuild proteins that can be taken in byanimals (5, 6).●536728910411Decay●Atmospheric pool of nitrogenNitrogen-fixing bacteria in root nodules of legumesFertilizersSoiI nitrateNitrate taken up by plant rootsPlant and animal proteins789101112Dead organismsDecomposersNitrite bacteriaNitrate bacteriaDenitrifying bacteriaLightningNitrification●Nitrifying bacteria convert theammonia produced by decay intonitrates (9, 10) used by plants.Denitrification●Bacteria that use nitrates as analternative to oxygen in respirationreduce nitrates to nitrogen gas, thusreplenishing the atmosphere (11).© Diagram Visual Information Ltd.123456Nitrogen leaves plants and animalswhen they rot, and decomposers breakdown dead organic matter (7, 8).194Water cycleECOLOGYKey wordsrespirationtranspirationWater cyclewater cycleOne cycle—twocomponentsEarth’s water is always moving in acycle called the hydrologic or watercycle.● The water cycle is of paramountimportance to living things, but mostof the cycle actually takes placeoutside living organisms.●2Non-living cycleThe cycle begins whenwater evaporates from thesurface of the oceans (1).● As the moist air rises, itcools and condensesinto water vapor,which forms clouds(2).● Water then falls tothe Earth asprecipitation (3).Once on theground, some of thiswater is absorbedinto the soil (4).● Plants and animalstake up this groundwater and dischargeit into theatmosphere duringtranspiration andrespiration (5–7)● Some of theprecipitation doesnot penetrate Earth’s surface.
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