Contents
Table of Contents
Specification ........................................................................................................................................ 2-3
Ecosystems .......................................................................................................................................... 4-6
Ecosystems ............................................................................................................................................................................................................ 4
Abundance ............................................................................................................................................................................................................. 5
Investigating Populations (Core Practical 10) ....................................................................................................................................... 6
Succession .............................................................................................................................................................................................................. 7
Energy Transfers................................................................................................................................................................................................. 8
Photosynthesis .................................................................................................................................. 9-15
Chloroplasts ................................................................................................................................................................................................... 9-10
Energy Supply ....................................................................................................................................................................................................11
Photosynthesis...................................................................................................................................................................................................12
The Light-Dependent Reaction ...................................................................................................................................................................13
The Light-Independent Reaction ...............................................................................................................................................................14
Investigating Photosynthesis (Core Practical 11) ..............................................................................................................................15
Climate Change................................................................................................................................ 16-23
Evidence for Climate Change .......................................................................................................................................................................16
The Greenhouse Effect ...................................................................................................................................................................................17
Climate Change Models ..................................................................................................................................................................................18
The Effects of Climate Change .....................................................................................................................................................................19
The Effect of Temperature on Enzyme Activity ..................................................................................................................................20
The Carbon Cycle ..............................................................................................................................................................................................20
Investigating the Effect of Temperature on Rate of Reaction (Core Practical 12) ...............................................................21
Investigating the Effect of Temperature on the Development of Organisms (Core Practical 13) ................................22
Reducing Climate Change..............................................................................................................................................................................23
Evolution ......................................................................................................................................... 24-26
Evolution ..............................................................................................................................................................................................................24
Speciation .............................................................................................................................................................................................................25
The Scientific Community .............................................................................................................................................................................26
1
,Specification
5.1 Understand the terms ecosystem, community, population and habitat.
5.2 Understand that the numbers and distribution of organisms in a habitat are controlled by biotic and
abiotic factors.
5.3 Understand how the concept of niche accounts for distribution and abundance of organisms in a
habitat.
5.4 Understand the stages of succession from colonisation to a climax community.
5.5 Understand the overall reaction of photosynthesis as requiring energy from light to split apart the
strong bonds in water molecules, storing the hydrogen in a fuel (glucose) by combining it with
carbon dioxide and releasing oxygen into the atmosphere.
5.6 Understand how phosphorylation of ADP requires energy and that hydrolysis of ATP provides an
immediate supply of energy for biological processes.
5.7 Understand the light-dependent reactions of photosynthesis including how light energy is trapped by
exciting electrons in chlorophyll and the role of these electrons in generating ATP, reducing NADP
in photophosphorylation and producing oxygen through photolysis of water.
5.8 i) Understand the light-independent reactions as reduction of carbon dioxide using the products of
the light-dependent reactions (carbon fixation in the Calvin cycle, the role of GP, GALP, RuBP and
RUBISCO).
ii) Know that the products are simple sugars that are used by plants, animals and other organisms in
respiration and the synthesis of new biological molecules (polysaccharides, amino acids, lipids and
nucleic acids).
5.9 Understand the structure of chloroplasts in relation to their role in photosynthesis.
5.10 i) Be able to calculate net primary productivity.
ii) Understand the relationship between gross primary productivity, net primary productivity and
plant respiration.
5.11 Know how to calculate the efficiency of biomass and energy transfers between trophic levels.
5.12 Understand the different types of evidence for climate change and its causes (including records of
carbon dioxide levels, temperature records, pollen in peat bogs and dendrochronology), recognising
correlations and causal relationships.
5.13 Understand the causes of anthropogenic climate change, including the role of greenhouse gases
(carbon dioxide and methane) in the greenhouse effect.
5.14 i) Understand that data can be extrapolated to make predictions and that these are used in models of
future climate change.
ii) Understand that models for climate change have limitations.
2
,Specification
5.15 Understand the effects of climate change (changing rainfall patterns and changes in seasonal cycles)
on plants and animals (distribution of species, development and life cycles).
5.16 Understand the effect of temperature on the rate of enzyme activity and its impact on plants, animals
and microorganisms.
5.17 Understand how evolution (a change in the allele frequency) can come about through gene mutation
and natural selection.
5.18 Understand the role of the scientific community (scientific journals, the peer review process,
scientific conferences) in validating new evidence, including proteomics and genomics, that supports
the accepted scientific theory of evolution.
5.19 Understand how isolation reduces gene flow between populations, leading to allopatric or sympatric
speciation.
5.20 Understand the way in which scientific conclusions about controversial issues, such as what actions
should be taken to reduce climate change or the degree to which humans are affecting climate
change, can sometimes depend on who is reaching the conclusions
5.21 Understand how knowledge of the carbon cycle can be applied to methods to reduce atmospheric
levels of carbon dioxide.
5.22 Understand how reforestation and the use of sustainable resources, including biofuels, are examples
of the effective management of the conflict between human needs and conservation.
CORE PRACTICAL 10:
Carry out a study on the ecology of a habitat, such as using quadrats and transects to determine distribution
and abundance of organisms, and measuring abiotic factors appropriate to the habitat.
CORE PRACTICAL 11:
Investigate photosynthesis using isolated chloroplasts (the Hill reaction).
CORE PRACTICAL 12:
Investigate the effect of temperature on the initial rate of an enzyme-catalysed reaction, to include Q10.
CORE PRACTICAL 13:
Investigate the effects of temperature on the development of organisms (such as seedling growth rate, brine
shrimp hatch rates).
3
,Ecosystems
5.1 Understand the terms ecosystem, community, population and habitat.
5.2 Understand that the numbers and distribution of organisms in a habitat are controlled by biotic and
abiotic factors.
5.3 Understand how the concept of niche accounts for distribution and abundance of organisms in a
habitat.
Key Terms
Ecosystem: All of the communities, organisms (biotic) and non-living (abiotic factors) living in a
particular area.
These factors are interacting and interdependent – they make up a self-contained
system, which is self-supporting in terms of energy flow.
Community: All of the organisms of different species that live in the same habitat and interact with
each other.
Population: All the interbreeding individuals of one species in a habitat.
Population Size: The number of individuals of one species in a particular area.
Habitat: The place with a distinct set of conditions where an organism lives.
Abiotic Factors: The non-living features of an ecosystem.
E.g. Light intensity, climate, pollution, catastrophes.
Biotic Factors: The living features of an ecosystem.
E.g. Competition, disease, predation, mutualism.
Abundance: The number of individuals of one species in a particular area.
Distribution: Where a species is in a particular area.
Niche
• Niche: The role of a species within its habitat, including its biotic and abiotic interactions.
• Every species has its own unique niche – a niche can only be occupied by one species.
• The abundance of different species can be explained by the niche concept:
• Two species occupying similar niches will compete, so fewer individuals of both species will be able
to survive in the area.
• The distribution of different species can be explained by the niche concept:
• Organisms can only exist in habitats where all of the conditions that make up their role exist.
Distribution
• Distribution varies due to abiotic factors – organisms can only exist where the abiotic factors they
can survive in exist.
• Distribution also varies due to biotic factors – if two species are competing, but one is better adapted
to its surroundings, the less well-adapted species is likely to be out-competed.
4
, Abundance
5.2 Understand that the numbers and distribution of organisms in a habitat are controlled by biotic and
abiotic factors.
Abundance
• The population size of any species varies because of biotic and abiotic factors.
• When conditions are ideal for a species, organisms can grow fast and reproduce successfully.
• When conditions are not ideal for a species, organisms cannot grow fast or reproduce as successfully.
Interspecific Competition
• Interspecific Competition: Organisms of different species compete with each other for the same
resources.
• Interspecific competition between two species means that the resources available to both populations
are reduced.
• This means both populations will be limited in their access to resources, reducing growth and
reproduction, so population sizes will be lower for both species.
Intraspecific Competition
• Intraspecific Competition: Organisms of the same species compete with each other for the same
resources.
1. The population of a species increases when resources are plentiful.
As the population increases, there will be more organisms competing for the same space/food.
2. Eventually, resources such as space and food become limiting.
The populations then begin to decline.
3. A smaller population means that there is less competition for space and food, which is better for
growth and reproduction, so the population starts to grow again.
• Carrying Capacity: The maximum stable population size of a species that an ecosystem can
support.
Predation
• The population sizes of predators and prey are interlinked – as the population of one changes, it
causes the other population to change.
1. As the prey population increases, there is more food for predators, so the predator population grows.
2. As the predator population increases, more prey is eaten, so the prey population begins to fall.
3. This means there is less food available for the predators, so their population decreases (and so on).
• Predator-prey relationships are usually more complicated as there are other factors involved affected
either predator or prey.
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