Biology B1.4-1.8_sample

Biology B 1.4 – 1.8 What you should know Variation All living things show variation. This may be inherited, environmental or the result of selective breeding. Genetic information is carried in the form of genes on chromosomes in the nucleus of cells, and can cause differences between individuals. What is the name of the chemical from which genes are made? You will find out Interdependence and adaptation Organisms interact with one another in their environment. Where two organisms need the sam
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  What you should know You will fnd out 56 57 Variation All living things show variation. This may be inherited,environmental or the result o selective breeding.Genetic inormation is carried in the orm o genes onchromosomes in the nucleus o cells, and can causedierences between individuals. What is the name of the chemical from whichgenes are made? Environment Living things are adapted to survive in theirenvironment.Food chains show how energy rom the Sun passesrom one organism to another.The environment aects the distribution and typeo living organisms ound in a habitat.Human activity can damage the environment. How does sulfur dioxide pollutionaffect plants? Reproduction Animals and plants produce young by sexualreproduction.Sexual reproduction involves two parents.The new lie begins when a male sex cell and aemale sex cell use together. What is the correct term for the fusion of the two sex cells? Interdependence and adaptation > Organisms interact with one another in their environment.Where two organisms need the same resource which is in shortsupply, they must compete or it. They need to have adaptationsthat enable them to do this successully, in order to survive. > The environment oten changes, and animals and plants may notalways be able to survive these changes. Energy and biomass in ood chains > Energy rom the Sun ows along ood chains in biomass. > Energy is wasted during the transers, so there is lessbiomass towards the end o the chain than at the start. Waste materials rom plants and animals > Microorganisms break down (decay) waste materials romorganisms. This releases substances that plants need to grow. > Carbon is cycled between living organisms and the environment. Genetic variation and its control > Individuals belonging to the same species dier because odierences in their genes and their environment. > Sexual reproduction causes genetic variation amongstospring, whereas asexual reproduction produces geneticallyidentical ospring. Evolution > Darwin was the frst person to put orward the theory oevolution by natural selection. > Organisms that are best adapted to their environment aremore likely to survive and reproduce, passing on their genesto their ospring. Biology B 1.4 – 1.8  58 Blgy B1.4 59 ... animals competition resources ... animal competition reproduction GCSE Rrc Figure 1 : This is abattleground or survival. Figure 2 : Why do armers want to kill weeds growing intheir crops? Yo w fnd ot: > organisms competewith each other orresources> organisms competewith each other ormates> some organismscan live in extremeenvironments Dd y kw? One tiger may have a territory o up to75 square kilometres. Questions 7 Suggest two resources or which a amingohas to compete with other amingos. 8 Suggest two resources or which amingosdo not have to compete with other species. QuestionsQuestions 1 Suggest which o the resources, listed above,are also needed by animals. 2 Think o at least two more resources that mostanimals must get rom their environment. 3 Suggest the resources that plants are mostlikely to compete or in (a) a desert (b) a tropicalrainorest. 4 What eatures will give stags an edge in thecompetition or mates? 5 Suggest eatures that will give male turkeysthe best chance o getting a mate. 6 Suggest advantages o the way that turkeyscompete or mates, compared with the waythat stags compete or mates. Figure 4 : Maleturkeys display toattract emales. Figure 3 : Stags fght over the right to mate with the emalesin the herd. sl gh Many animals reproduce sexually. I there are notenough emales to go around, then the males willcompete or a mate.Animals may also compete or a ttoy – a space inwhich they can nd ood and a place to breed.Sometimes, the males do actually ght over mates andterritory. However, in many species o animals, themales use some kind o display to attract the emales. Coral rees are stunningly beautiuland look very peaceul. Yeterce battles are going on. Eachdierent coral is competing orspace on the ree. At their edges,they secrete chemicals that try tostop their neighbours growing intotheir own patch. All living organisms need resources rom theirenvironment in order to stay alive.For example, plants must have: > lht – to photosynthesise and make ood > wat – to keep cells alive, to transport substancesaround and or photosynthesis > spac – or room to put down roots and spread outleaves to capture light > ntnts – such as nitrates rom the soil. Competition Oten, resources that organisms need are in shortsupply. There are not enough or every plant or animalto get what it needs.When this happens, organisms have to compt orresources. This does not oten mean that they actuallyght over them. They just have to nd ways o beingbetter at getting them than others are.For example, plants compete or light – the ones thatgrow tallest win the competition.The individuals best at competing are the most likelyto survive. Those not good at getting resources are themost likely to die. Cmpg  rprdcAvdg cmp Competition wastes energy. Having to share resourceswith other organisms reduces an organism’s chances osurviving and having large numbers o ospring.Many organisms have become able to live in placeswhere ew others can survive. Although these placesmake survival tough, there is no need to shareresources. This can increase chances o success.For example, famingos are able to eed in lakes thatare so alkaline that almost nothing else can survivethere – except the shrimps and small aquatic insectsthat they eat. Cmp Figure 5 : Flamingos eed and nest where ew otherorganisms can survive.  60 Blgy B1.4 61 ... animal adaptation ... extremophiles or students Clr ad rvval Animals are coloured or dierentreasons. Some are camoufaged sowell that they blend in perectly withtheir surroundings. Some male animalsare vividly coloured in an attempt toattract a mate. Others are very brightlycoloured to warn o predators. Adapa r rvval Figure 4 : How a camel is adapted or desert lie. Questions 5 Draw an outline o a polar bear. Addannotations, like those on Figure 4,to explain how the polar bear isadapted to live in the Arctic. Questions 6 Enzymes rom microorganisms that live in hotsprings have many uses in industry. One example isan enzyme added to washing powder. Suggest whythese enzymes are especially useul. Dd y kw? The animal with the longest ur is the musk ox.It lives in very cold northern areas o Europe.Each hair is about 70 cm long. Questions 1 Explain what ‘adaptation’ means. 2 How are gerbils adapted or living ina desert? 3 Give one way in which an Arctic ox isadapted to live in its habitat. 4 List some animals that have warningcolouration and are poisonous. Suggestsome that have warning colouration butare not poisonous. Yo w fnd ot: > organisms haveadaptations thathelp them survivein their habitat> how animals in theArctic are adaptedto conservebody heat> how plants indeserts are adaptedto conserve water Figure 5 : The bright colours in this hot spring aregrowths o microorganisms. The temperature o thewater may be as high as 90 ºC. Adapg  cmp Plants and animals must have eatures that allow them tosurvive in their habitat. These eatures are adaptatons .Well adapted organisms can compete successully or thethings they need. I they are not adapted or lie in aparticular habitat they will either die or move elsewhere. Living in dry places Plants that live in dry places usually have: > long, wide-spreading roots. The roots grow deep into thesoil, to reach water. > small leaves. The small surace area reduces the amount owater evaporating into the dry air. > tissues (groups o cells) that can store water.Animals that live in dry places: > must be able to manage without drinking much water.Gerbils do not need to drink at all. They get enough waterby eating seeds and other plant material.Desert animals: > oten have large ears. A large surace area helps the animallose body heat and stay cool. Living in cold places Animals that live in very cold places, such as the Arctic, oten: > have thick ur and thick layers o at. This insulation helpsthe animal reduce heat loss rom its body to the icy air. > are coloured white, or camoufage against snowand ice. Special adaptations Many plants and animals have thorns, poisons and warningcolours to deter predators. Throughout the animal world,red and black or yellow and black mean ‘I am poisonous –don’t eat me’. Many animals cheat: they have warningcolouring even though they are not poisonous. Caml ad plar bar Figure 4 shows how camels are adapted or lie in deserts. exrm vrm In some habitats, conditions are so extreme that it is dicultto imagine how anything at all can be adapted to live there.Yet, so ar, living things have been ound in everyenvironment we have been able to explore on Earth.Organisms that can live in very dicult environments arecalled xtmophls .In the really extreme places, it is oten only microorganismsthat can survive. They have been ound around deep seavolcanic vents at 400 °C and in the Arctic at –20 °C. In thedeepest part o the pacic Ocean, some microorganismssurvive at pressures 1000 times greater than at the surace.Others survive in water where the salt concentration isvery high.For most organisms, these conditions would be lethal.Enzymes and other protein molecules quickly lose their shapei they get too hot. These microorganisms must have verystable protein molecules that are not aected by suchhigh temperatures. Figure 1 : Can you spot the stick insect? Figure 2 : How is this cactus adapted or survival in adry desert? Figure 3 : AnArctic ox. can drink 20 litresof water in just afew minutesstomach can hold over20 liters of watervery little urinelong legs whichkeep it above thehot groundfat stored here – can beconverted to ‘metabolic water’’no insulating fatunder the skin  62 Blgy B1.4 63 ... animals plants environmental change GCSE ... environmental change living non-living actors ... bee decline Cpg wh chag This Arctic hare is beautiullycamoufaged – or is it? It is adaptedto blend in with the snow, but thisyear there is no snow. Changes inan animal’s environment can makesurvival very dicult. evrmal chag Figure 4 : A red squirrel in Dorset. Questions 3 Give one example o the eect on the distribution o a specieso (a) a changing non-living actor (b) a changing living actor. Questions 4 So ar, the idea that eeding on just one sort o pollen, suchas rapeseed pollen, might be contributing to the reduction inbee numbers is only a hypothesis. Suggest how this hypothesiscould be tested. 5 Bee numbers in the UK may continue to all. Suggest howthis could aect the numbers and distribution o other species. Dd y kw? Some researchers predict that theUK’s average temperature will goup by 4 ºC by 2080. Questions 1 Explain why changes in theenvironment can make itdifcult or plants or animalsto survive. 2 Describe how anenvironmental change hascaused a change in thedistribution o a species. Yo w fnd ot: > an organism’senvironment canchange> changes can becaused by living ornon-living actors> environmentalchanges can aectthe distribution oorganisms Figure 1 : Adaptations cannot always keepup with a changing environment. Figure 2 : Roesel’s bush cricket is spreadingacross England. Figure 3 : What will happen to the Scottishprimrose when the climate gets warmer? Gg warmr The environment is alwayschanging. This was happening evenbeore people lived on Earth. Now,we have extra changes to contendwith, such as global warming.All living organisms must beadapted or survival in a particularenvironment. I that environmentchanges, they may no longer beable to survive.For example, in the UK, averagetemperatures are slowly increasing.For some species, that is goodnews. Species that are adapted tolive in warm places are spreadingnorthwards. They are spreadingurther than they have ever beenable to live beore.For other species, such as theScottish primrose, the news is notso good. It grows only on the coasto the ar north o Scotland. Ca  chag Some changes are caused by non-lvn actos in the environment. Forexample, global warming is aecting temperature and rainall. In the UK,the mean annual temperature is rising. It is dicult to pick out changes inthe pattern o rainall in the UK, as this is always very variable. However,in other places, such as central Australia, there seems to be a lot less rainthan there used to be.Other changes are caused by living actors. For example, at the end o the19th century, all squirrels in the UK were red squirrels. Then the greysquirrel was introduced rom North America. They seem to be betteradapted than red squirrels, or survival in the UK, and out-compete themor ood. Also, grey squirrels seem to be immune to a virus that they carry.The virus is deadly to red squirrels. In England, red squirrels are now onlyound in a ew places. They are in decline in the rest o the UK, as well. th dapparg b Many people keep bees or honey production. Honeybees are also veryimportant in pollinating fowers that will develop into ood crops, such asbeans and rapeseed.In recent years, there has been a decline in the numbers o honeybees.Sometimes, whole colonies seem to have been wiped out overnight.Various suggestions have been put orward to explain this dramatic all inthe numbers o honeybees. They include: > an increase in parasites, such as the varroa mite and a virus called IAPV > increased use o insecticides > climate change > reduction in the number o dierent plant species (plant diversity). Beesthat eed on pollen and nectar rom only a ew species o plants seem tohave less eective immune systems. Figure 5 : How might the increasedamount o rapeseed that is grown in theUK contribute to the decline in numberso honeybees?   Key year of first record1886 – 19801980 – 19901990 – 20002000 – 2006 Key areas in which theScottish primrose is found  
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