The Natural Environment and Species Survival
A2 compulsory unit Externally assessed 7.1 Unit description Topic 5: On the wild side
This topic builds an appreciation that photosynthesis is the primary process that underpins the majority of ecosystems, and provides students with an understanding of how ecosystems
work. The topic continues by looking at whether climate change will lead to extinction of species or evolution by natural selection, and looks at the evidence for global warming and its effects on plants and animals. By the end of the topic students should appreciate how scientific understanding can make us aware of our responsibilities as stewards of the environment.
This topic starts by looking at how forensic pathologists use a wide variety of analytical techniques to determine the identity of a person or other animal, and to establish the time and cause of death of an organism, including humans. It then considers how bacteria and viruses use a variety of routes into their hosts and how hosts have evolved barriers and internal mechanisms to
combat infections. These protections are not always successful and many people in the world still die from infectious diseases. This topic also investigates the evolutionary battles that take place between invading pathogens and their hosts.
7.2 Assessment information
This unit is assessed by means of a written examination paper, which carries 90 marks, lasts 1 hour 30 minutes and will include: objective questions
and will also cover:
How Science Works
Unit 4 The Natural Environment and Species Survival
7.3 Topic 5: On the wild side
Students will be assessed on their ability to:
1 Demonstrate knowledge and understanding of the How
Science Works areas listed in the table on page 13 of this
11 Describe how to carry out a study on the ecology of a
habitat to produce valid and reliable data (including
the use of quadrats and transects to assess abundance
and distribution of organisms and the measurement
of abiotic factors, eg solar energy input, climate,
topography, oxygen availability and edaphic factors).
10 Explain that the numbers and distribution of organisms in a habitat are controlled by biotic and abiotic factors.
12 Explain how the concept of niche accounts for distribution and abundance of organisms in a habitat.
13 Describe the concept of succession to a climax community. 14 Outline the causes of global warming – including the role of greenhouse gases (carbon dioxide and methane, CH4
) in the
18 Analyse and interpret different types of evidence for
global warming and its causes (including records of carbon
dioxide levels, temperature records, pollen in peat bogs
and dendrochronology) recognising correlations and causal
19 Describe that data can be extrapolated to make predictions, that these are used in models of future global warming, and that these models have limitations.
20 Discuss the way in which scientific conclusions about
controversial issues, such as what actions should be taken to reduce global warming or the degree to which humans are
affecting global warming, can sometimes depend on who is
reaching the conclusions.Context approach – Salters-Nuffield Advanced Biology Project Edexcel GCE in Biology © Edexcel Limited 2010 Section C
The Natural Environment and Species Survival Unit 4
15 Describe the effects of global warming (rising temperature, changing rainfall patterns and changes in seasonal cycles) on plants and animals (distribution of species, development and life cycles).
16 Explain the effect of increasing temperature on the rate of enzyme activity in plants, animals and micro-organisms.
17 Describe how to investigate the effects of temperature
on the development of organisms (eg...