Identify four reasons why the genetic diversity of a population may change over time.

Explain how changes in the concentration of stratospheric and tropospheric ozone in the atmosphere can affect global biodiversity.

Environmental value systems differ in how they view the importance of biodiversity and this could influence a community’s approach to conservation.

Discuss how these different perspectives, including your own, may influence approaches to conservation.

mutation may lead to new genotypes/increased diversity;

natural selection/survival of fittest may eliminate some genotypes/reduce diversity;

(human activities) eg pollution/hunting/habitat destruction/alien species may reduce population/diversity / lead to a bottleneck effect;

migration causing mixing of populations/subjection to new selective pressures;

climate change may eliminate certain genotypes/reduce diversity;

…or lead to evolution of new genotypes/increase diversity;

(tectonic activity may create) natural barriers leading to divergent evolution/speciation/greater diversity;

genetic drift/random loss of genes;

mixing of GMOs/selectively bred/farmed escapees introduces new genes to wild populations.

Accept any other reasonable suggestions.
Responses that identify relevant factors eg “mutation”, but do not identify why/how this influences diversity should not gain full credit.
Award [1 max] for responses that list three valid factors without identifying how they influence diversity.
Award [2 max] for responses that identify four such factors.
Award [1] for each correct reason identified, up to [4 max].

Award [1] for the following point:

stratospheric ozone has decreased and (production of) tropospheric ozone has increased;

Award [1] for each part of the explanation given below, up to [6 max].

change in stratospheric ozone allows more UV radiation to reach earth;
…which causes mutations/damage to DNA/cancers;
…(possibly) resulting in death of organisms/reduction in biodiversity;
…also reduces plant growth/NPP/especially phytoplankton / damages chlorophyll;
…affecting populations all along food chain/reducing diversity of food web; [4 max]

change in tropospheric ozone in urban areas gives rise to photochemical smog;
…that is toxic (to humans/other species);
…damages plant leaves reducing NPP of ecosystems/food chains;
…tropospheric ozone is a greenhouse gas contributing to global warming/climate change;
…resulting in population declines/death/reduction in biodiversity; [4 max]

Do not credit the common misconception that ozone depletion/UV radiation leads to global warming (its connection, if any, is negligible).

The following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although “ESS terminology” has been conflated with “Understanding concepts”). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.

Answers may include:

• understanding concepts and terminology of environmental value systems, biodiversity, habitat/species/genetic diversity, ecocentric/anthropocentric/technocentric, bio-rights, intrinsic value, stewardship, conservation areas/national parks, in-situ/ex-situ conservation, species vs habitat approach, ecotourism; gene banks, plantations, in vitro development, etc
• breadth in addressing and linking differences in the importance attached to biodiversity by different value systems and associated strategies for conservation eg ecocentrics will attach particular importance to intrinsic value of biodiversity and the rights of all species, their focus will be on minimising any human intervention, conserving habitat diversity and pristine ecosystems, in-situ conservation areas/national parks, technocentrics may attach particular importance to the potential resources that biodiversity provides for human population, they may focus more readily on species more useful to humans and the potential of genes in providing resources, the use of gene banks and technology for in vitro development/ex-situ breeding programmes of “useful” species, anthropocentrics will attach particular importance to the ability of biodiversity in stabilising ecosystems so they can be managed for human benefit, through ecotourism, sustainable harvesting, conservation efforts will depend heavily on social engagement/legislation, etc
• examples of environmental value systems eg deep ecologists, ecocentric, anthropocentric, environmental managers, technocentric, cornucopian, and approaches to conservation eg habitat/in-situ conservation, ex-situ zoos/breeding programmes, ecotourism, gene banks/genetic engineering/in vitro development, flagship species
• balanced analysis of how different perspectives on biodiversity adopted in different value systems can influence the emphasis and selection of conservation strategies
• a conclusion that is consistent with, and supported by, analysis and examples given eg “My own perspective is rather on the borderline of ecocentric and anthropocentric viewpoints because, unlike the more extreme ecocentrics, I do believe humans have a unique responsibility in the natural world. And yet, the anthropocentric view of biodiversity as a pragmatic means to an end lacks some of the mystery and spirituality I associate with nature that is more evident in the ecocentric’s perspective.”

Refer to paper 2 markbands, available under the "your tests" tab > supplemental materials.

Question 7 was the most popular choice. A good proportion of candidates could identify at least a couple of factors affecting genetic diversity although further answers were commonly too vague for full credit, e.g. human influence; genetic engineering. A significant minority mistakenly addressed species diversity in communities.

A significant minority showed a clear understanding of the differences between stratospheric and tropospheric ozone and their impacts. However, a large majority showed profound confusion by linking ozone depletion in stratosphere with global warming and climate change. Many made no distinction between stratospheric and tropospheric ozone.

Most candidates were able to distinguish different value systems …although their distinctions were commonly vague and somewhat caricatured/simplistic. A significantly smaller group were able to link the value systems with specific conservation strategies/approaches.