Unit overview
Biological Sciences Unit 3B
Conservation
Evidence for
evolution
Mechanisms
of evolution
Variation
DNA
Content cells
Investigating and communicating in biology
Biological systems
Biological change
Evidence for
evolution
Mechanisms
of evolution
Variation
DNA
Unit content
Conservation
Content cells
Ecosystems: biodiversity and sustainability
Ecosystem resilience relies on maintaining
biodiversity in order to be sustainable and
productive. Conservation strategies are developed
to address environmental challenges – natural or
human-induced.
Conservation

rationale for the effective conservation of
biodiversity within natural ecosystems

conservation projects and strategies for
maintaining biodiversity and the prevention of
extinction including:
○ genetic strategies, eg gene/seed banks,
captive breeding programs, DNA profiling,
development of new strains
○ environmental strategies, eg biological
control, reafforestation, introduced species,
pest control
○ management strategies, eg national parks,
protected zones, licences, open seasons.
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Conservation
Evidence for
evolution
Variation
DNA
Unit content
Mechanisms of
evolution
Content cells
Continuity of species
DNA is a self-replicating and information-carrying
molecule. The manipulation of DNA has led to a
range of applications of biotechnology, particularly
in agriculture and environmental conservation.
Individuals within a species show variety in a range
of characteristics. Change in a species, over time, is
due to the selection of inheritable characteristics
best suited to the environment.
DNA

replication of DNA

protein synthesis.
Recombinant DNA technology

techniques:
○ restriction enzymes
○ ligation
○ gel electrophoresis
○ polymerase chain reaction (PCR)
•
processes
○ gene cloning
○ transgenic organisms
○ DNA profiling.
Applications of DNA technologies

recombinant DNA technology and DNA
identification technology in
○ agriculture
○ environmental conservation.
Variation


significance of meiosis
sources of variation including:
○ mutations
○ the independent assortment of chromosomes
○ crossing over during meiosis
○ random mating.
Isolation

barriers to gene flow.
Selection

process of natural selection leading to change in
characteristics of a population, eg pesticide
resistance, bird beaks, flowers and pollinators
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
selective pressures leading to change or
extinction, eg loss of habitat, predation

practical application of artificial selection, eg the
selective breeding of animals and crops.
Evidence for
evolution
Mechanisms
of evolution
Variation
DNA
Unit content
Conservation
Content cells
Speciation/evolution


gene pools
changes in allele frequency due to:
○ natural selection
○ sexual selection
○ genetic drift, eg the founder effect.
Evidence for evolution

evolutionary relationships between groups using
physiological, molecular and evidence in
phylogenetic trees

evidence for evolution including:
○ fossils
○ homologous structures
○ comparative anatomy
○ embryology of vertebrates
○ comparative biochemistry and genetics.
Working as a biologist
Planning and conducting biological research

design an investigation for an hypothesis

devise a safe investigation involving a number
of controlled variables.
Evaluating and communicating as a biologist

analysis of current biological issues using
scientifically informed sources

environmental and ethical considerations
associated with practices of biotechnology

limitations of experimental design

influence of biological research on
decision-making and management of biological
systems

implications for careers and commercial
applications of biological research.
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Assessment weightings
Conservation
10%
Evidence for
evolution
Investigation: practical skills
Mechanisms
of evolution
DNA
Variation
Assessment types
5%
5%
10%
11
12
10%
Investigation: fieldwork
Extended response
Tests
10%
10%
Examination
40%
Notional hours
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