B2:Understanding Our Environment Revision List

GCSE Biology B2(OCR B712) Understanding Environment

OCR and AQA GCSE Core Science B2 Revision for the new 9-1 course. If you are revising for your B2 Biology exam then this revision list is a good place to start.

B2:Understanding Our Environment Revision List

October 22, 2017 admin

B2A CLASSIFICATION

  • What characteristics are used to place organisms into the five Kingdoms.
  • Organisms can be classified into groups according to shared characteristics.
  • 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.
  • 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.
  • Explain some of the problems of classifying organisms into species, to include:(HL)
    • hybrids
    • organisms that only reproduce asexually
    • evolution as a continuing process.

 

  • 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)

B2B ENERGY FLOW

  • 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.

 

  • Explain the difficulties in constructing pyramids (HL):
    • organisms may belong to more than one trophic level
    • the problems with measuring dry biomass.

 

  • 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)

B2C RECYCLING

  • Survey of local recycling schemes.
  • Compare local recycling schemes with national and international recycling schemes.
  • Composting activities.
  • Observation/measurement of leaf decomposition in hedges.

 

  • Recognise that as animals and plants grow they take in chemicals and incorporate elements from these into their bodies.
  • Describe the importance of this decay process in making elements available again to living organisms.
  • Recognise that many soil bacteria and fungi are decomposers, which decay dead organisms.
  • Recall that when animals and plants die and decay the elements in their bodies are recycled.
  • 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.
  • 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

 

  • 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.

 

  • 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.

 

  • 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

 

B2D INTERDEPENDENCE

  • 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)

 

  • 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)

B2E ADAPTATION

  • 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.
  • 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).
    • behavioural and anatomical methods of increasing heat loss
    • behavioural methods of reducing heat gain.

 

  • Explain how adaptations to hot environments help organisms survive, to include:
  • 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.

 

  • 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.
  • 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.

B2F NATURAL SELECTION

  • 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.
  • 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.

 

  • 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).
  • 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)

B2G POPULATION & POLLUTION

  • Recognise that the human population is increasing.
  • 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.
  • 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 population growth is the result of the birth rate exceeding the death rate.
  • Understand that the human population is increasing exponentially.
  • 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)
    • water pollution – waterlouse sludgeworm, rat-tailed maggot and mayfly larva
    • air pollution – lichen.

 

  • Explain how the presence/absence of indicator species helps to indicate the level of pollution:
  • 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)

B2H SUSTAINABILITY

  • climate change
  • habitat destruction
  • hunting
  • pollution
  • competition.

 

  • Explain why organisms become extinct or endangered by
  • Describe how endangered species can be conserved:
    • protecting habitats
    • legal protection
    • education programmes
    • captive breeding programmes
    • seed banks
    • creating artificial ecosystems.

 

  • Recognise that a sustainable resource can be removed from the environment without it running out.
  • Discuss the reasons why certain whale species are close to extinction.
  • Interpret data which shows that whale species’ distributions depend on their feeding habitats.
  • Recall that some resources can be maintained like:
    • fish stocks
    • woodland.

 

  • 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)
  • 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.
  • 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)