GCSE Biology B2(OCR B712) Understanding Environment

Year 10 core science revision

  • Organisms can be classified into groups according to shared characteristics.
  • What characteristics are used to place organisms into the five Kingdoms.
  1. What characteristics place organisms into the different classes of arthropod,(FT):
    • insects
    • arachnids
    • crustaceans
    • myriapods
  • Research the work of John Ray and Carl Linnaeus in developing a modern classification system.
  1. Recognise that organisms of the same species:
    • may show great variation
    • have more features in common than they do with organisms of a different species.
  • Understand why similar species tend to live in similar types of habitats
  • Understand that the variety of life is a continuous spectrum which makes it difficult to place organisms into distinct groups.
  • Describe the classification of organisms into kingdom, phylum, class, order, family, genus and species.
  • Explain the importance of classification of species in terms of identifying evolutionary and ecological relationships.
  • Describe classification systems to include natural (based on evolutionary relationships) and artificial (for purposes of identification)(HL)
  • Explain how the use of DNA sequencing information has led to changes in understanding of classification.(HL)
  • Understand why systems of classification change over time.(HL)
  • Understand that the evolutionary relationships between organisms can be displayed using evolutionary trees.
  • Understand how the evolutionary relationships of organisms in a group can be modelled by analysing multiple characteristics and how this has been facilitated by ICT.(HL)
  • Define the term 'species' as a group of organisms which are capable of interbreeding to produce fertile offspring.
  • Explain the importance of the binomial system as the international basis for naming species.
  1. Explain some of the problems of classifying organisms into species, to include:(HL)
    • hybrids
    • organisms that only reproduce asexually
    • evolution as a continuing process.
  1. Recall that closely related species:
    • share a relatively recent ancestor
    • may have different features if they live in different types of habitats.
  • Explain how similarities and differences between species can be explained in terms of both evolutionary and ecological relationships.(HL)
  • Explain the term trophic level.
  • Understand that there are organisms other than green plants that are producers.
  • Explain why some organisms are both primary and secondary consumers.
  • Explain how changes in the population of one organism may affect the other organisms in a food web.
  • Explain how energy from the Sun flows through food webs.
  • Interpret data on energy flow in food webs.
  • Understand how pyramids of numbers show the dry mass of living material at each stage of a food chain.
  • Construct pyramids of biomass from given information.
  • Explain why pyramids of numbers and pyramids of biomass for the same food chains can be different shapes.
  1. Explain the difficulties in constructing pyramids (HL):
    • organisms may belong to more than one trophic level
    • the problems with measuring dry biomass.
  1. Explain how some energy is transferred to less useful forms at each stage (trophic level) in the food chain,:
    • heat from respiration
    • excretion
    • egestion
  • Describe how excretory products, faeces and uneaten parts can be used as the starting point for other food chains.
  • Explain how the efficiency of energy transfer explains the shape of pyramids of biomass.(HL)

  • Explain how the efficiency of energy transfer explains the limited length of food chains.(HL)

  • Calculate the efficiency of energy transfer.(HL)
  • Survey of local recycling schemes.
  • Compare local recycling schemes with national and international recycling schemes.
  • Composting activities.
  • Observation/measurement of leaf decomposition in hedges.
  • Recall that when animals and plants die and decay the elements in their bodies are recycled.
  • Recognise that many soil bacteria and fungi are decomposers, which decay dead organisms.
  • Describe the importance of this decay process in making elements available again to living organisms.
  • Recognise that as animals and plants grow they take in chemicals and incorporate elements from these into their bodies.
  1. Recall that two of the most important elements that are required are:
    • Carbon and Nitrogen
  • Recall that carbon is taken up by plants as carbon dioxide.
  • Carry out an experiment to test soil for nitrates.
  • Examine clover roots to see nodules.
  • Make a nitrogen cycle snakes and ladders game.
  • Investigate nitrogen Fixing bacteria (see Practical Microbiology for Secondary Schools).
  • Recall that nitrogen is taken up by plants as nitrates.
  • Recall the abundance of nitrogen in the air (78%)
  • Explain why nitrogen gas can't be used directly by animals or plants, in terms of its reactivity.
  • Explain why recycling of nutrients takes longer in waterlogged or acidic soils than it does in well drained neutral soils.
  1. Explain how carbon is recycled in nature, limited to:
    • plants removing carbon dioxide from the air by photosynthesis
    • feeding passes carbon compounds along a food chain or web
    • plants and animals releasing carbon dioxide into the air, as a product of respiration
    • burning of fossil fuels (combustion) releasing carbon dioxide
    • soil bacteria and fungi, acting as decomposers, releasing carbon dioxide into the air
  1. Explain how carbon is recycled in nature(HL):
    • marine organisms making shells made of carbonates
    • shells becoming limestone
    • carbon returning to the air as carbon dioxide during volcanic eruption or weathering
    • oceans absorbing carbon dioxide, acting as carbon sinks.
  1. Explain how nitrogen is recycled in nature:
    • plants taking in nitrates from the soil to make protein for growth
    • feeding passes nitrogen compounds along a food chain or web
    • nitrogen compounds in dead plants and animals being broken down by decomposers and returning to the soil.
  1. Explain how nitrogen is recycled in nature:(HL)
    • soil bacteria and fungi, acting as decomposers,converting proteins and urea into ammonia
    • the conversion of this ammonia to nitrates by nitrifying bacteria
    • the conversion of nitrates to nitrogen gas by denitrifying bacteria
    • the fixing of nitrogen gas by nitrogen- Fixing bacteria living in root nodules or in the soil, or by the action of lightning
  • Explain how competition may influence the distribution and population size of animals or plants, related to the availability of food, water, shelter, light and minerals.
  • Interpret data which shows that animals and plants can be affected by competition for resources, including population sizes and distribution data.
  • Explain how the size of a predator population will affect the numbers of prey and vice versa.
  • Describe one example of such a relationship, limited to cleaner species, to include oxpecker and buffalo.
  • Explain how similar animals in the same habitat will be in close competition.
  • Describe how organisms within a species compete in order to survive and breed.
  • Use the terms interspecific (between species) and intraspecific (within species) to describe given examples of competition and explain why intraspecific competition is often more significant.(HL)
  • Explain what is meant by the term ecological niche.(HL)
  • Understand that similar organisms will occupy similar ecological niches.(HL)
  • Explain how the populations of some predators and their prey show cyclical fluctuations in numbers.
  • Explain why the cycles of population for predator and prey are out of phase with each other.(HL)
  1. Describe other types of interdependence between organisms to include:
    • parasitism, where the parasite benefits to the living host's detriment, including Fleas and tapeworms
    • mutualism, where both species benefit including cleaner species and pollination by insects.
  • Explain how the interdependence of organisms determines their distribution and abundance.(HL)
  • Explain why nitrogen-fixing bacteria in the root nodules of leguminous plants are an example of mutualism.(HL)
  1. Explain how some animals are adapted to be successful predators:
    • binocular vision to judge distance and size
    • hunting strategy
    • breeding strategy
  • Recall that animals and plants that are adapted to their habitats are better able to compete for limited resources.
  1. Explain how some animals are adapted to avoid being caught as prey:
    • eyes on side of head for wide field of view
    • living in groups (herds or shoals) to reduce the chance of being caught
    • cryptic and warning colouration
    • mimicry
    • breeding strategy (synchronous breeding).
  1. Explain how adaptations to cold environments help organisms survive, to include:
    • anatomical methods of reducing heat loss including insulation and surface area
    • behavioural adaptations, including migration and hibernation.
  1. Explain how adaptations to hot environments help organisms survive, to include:
    • behavioural and anatomical methods of increasing heat loss
    • behavioural methods of reducing heat gain.
  1. Explain how adaptations to dry environments help organisms survive, to include:
    • behavioural, anatomical and physiological methods for coping with lack of water
  • Analyse surface area to volume ratios in the context of different environmental stresses.(HL)

  • Explain how counter-current heat exchange systems (eg in penguins) minimise heat loss.(HL)

  • Understand that some organisms are biochemically adapted to extreme conditions, including different optimum temperature for enzymes in extremophiles and organisms with antifreeze proteins.(HL)
  • Explain how animals and plants that are adapted to an environment are better able to compete for limited resources.
  1. Describe how some organisms are:(HL)
    • specialists, which are well suited to only certain habitats
    • generalists, which can live in a range of habitats but can easily be out-competed.
  • Know how natural selection takes place.
  • Understand Charles Darwin's observations and theories.
  • Understand the role of Alfred Russell Wallace in developing the theory of natural selection.
  • The peppered moth.
  • Identify variations within a population of organisms of the same species.
  • Explain why animals and plants that are better adapted to their environment are more likely to survive.
  • Recognise that over long periods of time, groups of organisms can change and that this is called evolution.
  • Understand how when environments change, some animal and plant species survive or evolve but many become extinct.
  • Know the difference between Lamarck ideas about evolution and Darwins.
  1. Recall that:
    • many theories have been put forward to explain how evolution may occur
    • most scientists accept the theory of natural selection first put forward by Charles Darwin.
  1. Understand Darwin's theory of evolution by natural selection:
    • presence of natural variation
    • competition for limited resources
    • survival of the fittest
    • inheritance of 'successful' adaptations
  • Recall that adaptations are controlled by genes and that these genes can be passed on to the next generation.
  • Explain how over long periods of time the changes brought about by natural selection may result in the formation of new species.(HL)
  • Understand why speciation requires geographical or reproductive isolation of populations. (HL)
  • Explain the reasons why the theory of evolution by natural selection met with an initially hostile response (social and historical context).
  1. Recognise that natural selection as a theory is now widely accepted:
    • because it explains a wide range of observations
    • because it has been discussed and tested by a wide range of scientists
  • Explain how Lamarck's idea of evolution by the inheritance of acquired characteristics was different from Darwin's theory. (HL)
  • Explain why Lamarck's theory was discredited: his explanation did not have a genetic basis.(HL)
  • Recognise that the theory of natural selection has developed as new discoveries have been made, to include the understanding of inheritance. (HL)
  • Recognise that the human population is increasing.
  1. Recognise that the human population uses resources, some of which are finite, to include:
    • fossil fuels
    • minerals
  • Understand that pollution can affect the number and type of organisms that can survive in a particular place.
  1. Explain how as the human population increases, resource use increases and therefore more pollution is created; types of pollutants:
    • household waste
    • sewage
    • sulfur dioxide from burning fossil fuels
    • carbon dioxide from burning fossil fuels.
  • Understand that the human population is increasing exponentially.
  • Understand that population growth is the result of the birth rate exceeding the death rate.
  1. Explain the causes and consequences of:
    • global warming
    • Ozone depletion
    • acid rain.
  • Explain how the developed countries of the world, with a small proportion of the world's population,have the greatest impact on the use of resources and the creation of pollution. (HL)
  • Explain the term 'carbon footprint' in terms of the amount of greenhouse gases given off in a certain period of time. (HL)
  • Discuss the possible consequences of exponential growth. (HL)
  1. Explain how the presence/absence of indicator species helps to indicate the level of pollution:
    • water pollution - waterlouse sludgeworm, rat-tailed maggot and mayfly larva
    • air pollution - lichen.
  1. Describe how pollution can be measured:
    • by direct measurement of pollutant levels
    • by measuring the occurrence of indicator species.
  • Interpret data on indicator species. (HL)
  • Describe the advantages and disadvantages of using living and non-living methods of measuring levels of pollution. (HL)
  1. Explain why organisms become extinct or endangered by
    • climate change
    • habitat destruction
    • hunting
    • pollution
    • competition.
  1. Describe how endangered species can be conserved:
    • protecting habitats
    • legal protection
    • education programmes
    • captive breeding programmes
    • seed banks
    • creating artificial ecosystems.
  • Interpret data which shows that whale species' distributions depend on their feeding habitats.
  • Discuss the reasons why certain whale species are close to extinction.
  • Recognise that a sustainable resource can be removed from the environment without it running out.
  1. Recall that some resources can be maintained like:
    • fish stocks
    • woodland.
  1. Explain reasons for conservation programmes:
    • protecting human food supply
    • ensuring minimal damage to food chains
    • future identification of plants for medical purposes
    • cultural aspects.
  • Explain why species are at risk of extinction if the number of individuals or habitats falls below a critical level.
  • Explain why species are at risk of extinction if there is not enough genetic variation in the population. (HL)
  1. Evaluate a given example of a conservation programme in terms of (HL):
    • genetic variation of key species
    • viability of populations
    • available habitats
    • interaction between species
  • Recognise that both living and dead whales have commercial value: tourism when alive; food, oil and cosmetics when dead.
  • Describe issues arising from keeping whales in captivity: entertainment, research, captive breeding programmes and lack of freedom.
  • Recognise that some aspects of whale biology are still not fully understood: communication, migration patterns and survival at extreme depths. (HL)
  • Describe issues concerning whaling: getting international agreement, policing and enforcing such agreements and hunting for research. (HL)
  • Explain the term sustainable development as providing for the needs of an increasing population without harming the environment.
  1. Explain how fish stocks and woodland can be sustained and developed using:
    1. education
    2. quotas on fishing
    3. re-planting of woodland
  • Explain the importance of population size, waste products and food and energy demands in the achievement of sustainable development. (HL)
  • Understand that sustainability requires planning and co-operation at local, national and international levels. (HL)
  • Describe how sustainable development may protect endangered species. (HL)

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