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Doc Brown's Biology AQA GCSE Science-BIOLOGY 1 Revision Notes

Biology Unit B1.4 Interdependence and adaptation  Study Notes

BIOLOGY UNIT 1 Biology 1 for GCSE Science or GCSE Biology

REVISION NOTES GUIDE SUMMARY: What do you need to know for the examinations? What do you need to able to do in the exams? In AQA GCSE Science A examinations HT means for higher tier students only. Sorry, but I don't have much time to answer questions, but if you see any apparent errors or wish to comment, please email me. All my notes, learning objectives, comments for exam revision are based on the official AQA GCSE Science A Key Stage 4 syllabus specification.

AQA GCSE Science BIOLOGY 1 Unit B1.4 Interdependence and adaptation

  • Appreciate that organisms are well adapted to survive in their normal environment.

  • Know that population size depends on a variety of factors including competition, predation, disease and human influences.

  • Know that changes in the environment may affect the distribution and behaviour of organisms.

  • Using your knowledge and understanding be able to:

    • suggest how organisms are adapted to the conditions in which they live,

      • Examination questions will use examples that are unfamiliar to candidates.

    • observe the adaptations, eg body shape, of a range of organisms from different habitats,

    • develop an understanding of the ways in which adaptations enable organisms to survive,

    • suggest the factors for which organisms are competing in a given habitat,

      • Factors will be limited to light, water, space and nutrients in plants; food, mates and territory in animals.

    • evaluate data concerned with the effect of environmental changes on the distribution and behaviour of living organisms.


AQA GCSE Science BIOLOGY Unit B1.4.1 Adaptations

  • a) Know and understand that to survive and reproduce, organisms require a supply of materials from their surroundings and from the other living organisms there.

  • b) Know and understand that plants often compete with each other for light and space, and for water and nutrients from the soil.

  • c) Know and understand that animals often compete with each other for food, water, mates and territory. In the wild territorial disputes between species or members of a species are common - an example of competition. Those animals who are best adapted will nudge out of other species from a particular habitat.

    • In most UK woodlands, the grey squirrel from North America, has displaced the native red squirrel, principally because it out-competes for food. The grey squirrel can feed more at ground level and can digest acorns and red squirrels can't).

  • d) Know and understand that organisms, including microorganisms have features (adaptations) that enable them to survive in the conditions in which they normally live.

  • e) Know and understand that some organisms live in environments that are very extreme.

    • Know that so-called extremophiles may be tolerant to high levels of salt, high temperatures or high pressures.

    • Flamingos filter-feed on brine shrimp and blue-green algae and their pink or reddish color comes from carotenoid proteins in their diet of animal and plant plankton which can survive in the very salty lakes the flamingos fly to for feeding.

    • There are certain microorganisms, eg bacteria colonies, that live by hot volcanic vents of water on land (eg geysers) or on the seabed (where the vents are called 'black smokers').

    • There are creatures that happily live on the deep ocean beds where the pressure from the water above is enormous.

  • f) Know and understand animals and plants may be adapted for survival in the conditions where they normally live, eg deserts, the Arctic.

    • Know and understand that animals may be adapted for survival in dry and arctic environments by means of:

      • Changes to surface area - heat/water transfer factor

        • Desert animals eg in Africa, tend to have a large surface area/volume ratio to allow excess body heat to be readily lost. This helps overheating, particularly as they do not sweat much and produce smaller volumes of concentrated urine, both helping to reduce water loss.

        • Animals living in very cold climates eg the arctic regions and northern Europe and Russia, tend to have a smaller surface area/volume ratio to minimise heat loss. Their bodies need to compact with a minimum volume - 'roundish' to minimise the surface area through which heat is lost. The arctic fox and wolves have short ears and a short snout to minimise surface area, hence minimise heat loss.

      • Thickness of insulating coat

        • Desert animals have thinner coats than animals in colder climates, which aids heat loss.

        • Animals living very cold climates have thick hairy coats to minimise heat loss, but the fur must be in good condition to trap insulating air and keep cold water away from the skin. The fur of animals like the arctic fox is an extremely good insulator and can survive at temperatures as low as -50oC. It has a long winter coat with thick dense underfur. Bears, similarly, have thick fur coats.

      • Amount of body fat

        • Desert animals have thin layers of body fat compared to animals in colder climates, which aids heat loss.

        • Animals in arctic regions have thick layers of insulating fat or blubber AND these also act as an important energy store - fat/blubber has a very high calorific value, useful in lean times and scarcity of food. eg seals, penguins, polar bears, whales

      • Camouflage

        • Desert animals have sand coloured coats which give good camouflage to minimise being seen and attacked by predators, it also the enables animal to a predator itself, prey becomes the hunter!

        • Arctic animals like polar bears have white fair to blend in with the icy/snowy background to increase the chances of a kill. Smaller white coated animals are less likely to seen and caught. The white arctic fox is a mean hunter! Birds like the ptarmigan stand a better chance of survival from predators turning white in colour in winter, and brown in the summer, thereby blending into the landscape with the change in seasons

    • Know and understand that plants may be adapted to survive in dry environments by means of:

      • changes to surface area, particularly of the leaves - through which water is naturally lost by transpiration

        • To reduce the surface area, to reduce water loss, plants like cacti have thin spines instead of broader leaves.

      • water-storage tissues

        • Plants like cacti have relatively thick fleshy stems which contain groups of specialised cells that store water. Some giant cacti like the saguaro cactus in the deserts of Arizona (USA) can be 20m high and hold in storage several tonnes of water - more than enough to see it through the driest of dry seasons.

      • extensive root systems

        • Cacti generally have one of two kinds of root system. (i) Some have relatively few roots, but roots that can burrow deep into the ground to seek out underground water. (ii) Other cacti have many shallow spread out roots that can rapidly absorb water eg if it rains, which may be very infrequent in desert regions.

  • g) Know and understand that animals and plants may be adapted to cope with specific features of their environment, these specialised features include thorns, poisons and warning colours to deter predators eg

    • Roses have thorns, hedgehogs have needle like spikes/spines over the upper side of their body and can curl up to give all round protection, cacti have sharp spines to deter animals (herbivores) eating them, turtles, armadillos and tortoises have hard protective shells

    • Plants like ivy contain poisons, insects like bees and wasps have stings, some desert shrubs secrete toxic compounds into the soil to prevent other plants growing nearby

    • Some insects and other animals have very bright colours to look 'fearful' to potential predators.


AQA GCSE Science BIOLOGY Unit B1.4.2 Environmental change

  • a) Know and understand that changes in the environment affect the distribution of living organisms.

    • Exam question examples might include, but not limited to, the changing distribution of some bird species and the disappearance of pollinating insects, including bees.

  • b) Know and understand that animals and plants are subjected to environmental changes.

    • Realise that such changes may be caused by living or non-living factors

      living: Change in competitor (a new or rise/fall in native ones), spread of an infectious disease from parasites and pathogens, levels of prey available to hunt,

      • One species population might be affected by a 'living' factor. If it is the prey for some other animal, then in turn the predator is affected, so population changes are frequent in the animal world and can rise or fall significantly with the availability of food.

      • The decline in the bee population in many countries is attributed to them carrying pathogens/parasites and their food supply contaminated with pesticides - but nobody is quite sure, what is sure, is that bees immune system can't cope.

      • The spread of Dutch elm disease, and other diseases, are devastating tree populations.

    • non-living: Change in the average temperature or rainfall,

      • The average temperature in some northern European countries has risen, so populations of some bird species from southern areas eg the Mediterranean countries, are beginning to increase in northern Europe.

      • Acid rain, from the industrial revolution onwards, has affected forests and ecosystems in lake by decreasing the pH of water.

      • The English Channel separating England and France has become slightly warmer (only by 0.5oC in 100 years), so species of animals from warmer waters are moving north-east into warmer water ie the geographical distribution of marine life is changing.

  • c) Know and understand that living organisms can be used as indicators of environmental changes such as pollution.

    • Despite the presence of pollutants, some species of plants/animals can live in polluted air or water, but other organisms need clean air or clean water to survive and prosper.

      • The absence or presence of these indicator species e.g. from monitored population counts, can say much about whether a particular atmospheric or aquatic environment is relatively polluted or unpolluted.

      • These indicator species can be quite sensitive to their environment and we can put their sensitivity to their surroundings to good use in environmental monitoring and hopefully control things to improve matters.

      • These pollution indicators may live ...

        • ... on surface exposed to air e.g. lichen on rocks/stone walls, blackspot fungus on roses,

        • ... live in water e.g. mayfly larvae, stonefly larvae, freshwater shrimps, bloodworms, sludgeworms

    • Lichens can be used as air pollution indicators, particularly of the concentration of sulfur dioxide in the atmosphere.

      • The cleaner the air in the environment, the more varied species, and the greater numbers of an individual species of lichen colonies are seen on rocks and stone walls. You would observe the 'cleaner air' effect if you surveyed walls all the way from a polluted town or city centre to some rural location away from roads well beyond the town or city boundary, and no doubt note the greater the numbers and variety of lichen growing on the walls the further you where from the town/city centre.

      • Therefore, lichen species can be used as quite a sensitive air pollution indicator i.e. low populations of a limited number of lichen species indicates polluted air, usually from sulphur dioxide (SO2).

      • Particular lichens are sensitive to poisonous sulfur dioxide (even in very low concentrations of SO2) from fossil fuel burning - road vehicle exhausts, power station chimneys etc.

      • Blackspot fungus readily grows on roses in relatively clean unpolluted air, but does not grow as readily in polluted air - the fungus is killed by the polluting sulfur dioxide. One advantage an urban gardener has over a country gardener!

    • Invertebrate animals can be used as water pollution indicators and are used as indicators of the concentration of dissolved oxygen in water.

      • Lakes that are stagnant from overgrowth of algae (eutrophication) become devoid of oxygen at lower levels because the decay bacteria use up the oxygen. This decreases invertebrate populations and animals that feed on them, like fish, also decline - so whole food-chains and complex ecosystems are disrupted.

      • If rivers become polluted from raw sewage spills or silage spills, the concentration of pathogens rise (extra food for them e.g. nitrate nutrients) and these microorganisms use up the oxygen, so all species needing oxygen decline - which is nearly everything!

        • Certain bacteria will thrive in these conditions and consume oxygen in the process.

        • Some invertebrate species actually thrive in low oxygen polluted water e.g. a high population of blood worms and sludge worms indicates very polluted water.

      • Particular invertebrate animals like the mayfly larvae and stonefly nymphs are particularly sensitive to pollution, so their population size is a very good indicator of the purity of the water. The less pollution in the lake or river water, the less the growth of algae/bacteria etc. and the more oxygen dissolve in the water (less used up), therefore the more mayflies and stoneflies hatched out for the trout! and more trout for the fisherman! BUT only in clean unpolluted water!

        • Knowledge and understanding of the process of eutrophication is not required.

  • d) Environmental changes can be measured using non-living indicators (usually sensors) to monitor factors such as oxygen levels in water, temperature and rainfall.

    • You should understand the use of equipment to measure oxygen levels, temperature and rainfall, all of which are important indicators of environment change on land or in water and the bigger picture of global climate change.

      • Special meter probes can be dipped into water to measure oxygen levels, a bit like pH meter probes that measure pH (which is also an important indicator of relative acidity-alkalinity). A decline in aquatic oxygen levels as measured by an oxygen probe gives an immediate warning of pollution.

      • Temperature can be measured directly and very accurately with a mercury thermometer (being replaces on health and safety grounds), or, electronically using a thermocouple system. Average temperatures for the year, or seasonal averages, are important indicators of climate change. Both air and sea temperatures are monitored.

      • Specialised electronic instruments can automatically and continuously monitor air pollution levels of carbon monoxide, sulphur dioxide and ozone levels in the atmosphere.

        • The data can be continuously fed, stored and analysed in computer systems for detailed analysis of air pollution patterns on a long-term basis, so a decline or an improvement in environmental conditions can be seen and its progress monitored.

        • You can do the same with pH, oxygen level and temperature probes continually monitoring water systems like rivers.

      • Rainfall is easily monitored with a rain gauge, manually with a calibrated glass container (a bit like a measuring cylinder), or automatically by weighing the water collected with a sensitive balance. Like temperature, rainfall is an important aspect of regional climate data.

        • All of these monitoring systems can be fully automated these days and so 'automatic weather stations' can be set up in remote locations and data sent by radio to a weather centre or laboratory.

        • Satellites are being used to monitor several environmental factors eg decline of forests by burning and replace with cattle or crops, the area of ice/snow cover in arctic regions eg changes in the Greenland and Antarctic ice sheets. Even individual remote glaciers can be monitored - decline of some with temperature rise is concerning climate scientists studying global warming.


  • Any practical work and investigations you did should also be revised (which should also be revised, helps in understanding 'how science works' and context examination questions):

    • investigations of environmental conditions and organisms in a habitat such as a pond,

    • ‘hunt the cocktail stick’ using red and green cocktail sticks on a green background,

    • investigating the distribution of European banded snails,

    • investigating the behaviour of woodlice using choice chambers,

    • investigating the effect on plant growth of varying their environmental conditions, eg degrees of shade, density of sowing, supply of nutrients,

    • investigating particulate levels, eg with the use of sensors to measure environmental conditions,

    • the use of maximum–minimum thermometers, rainfall gauges and oxygen meters,

    • investigating the effect of phosphate on oxygen levels in water using jars with algae, water and varying numbers of drops of phosphate, then monitor oxygen using a meter,

    • computer simulations to model the effect on organisms of changes to the environment.


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