Science: Life on Planet Earth Final Exam Guide
1) Define Biodiversity.
Biodiversity: the various forms of life that can best survive the variety of conditions currently found on Earth.
2) Discuss some threats to biodiversity.
The Decline of Biodiversity and reasons for biodiversity loss is because:
Habitat destruction
Conversion- natural areas are converted to farms, housing, shopping malls industrial centers, etc
Introduction of exotic species- a species introduced into an area from somewhere else
In some cases, humans have dispersed species on purpose; for instance, many plants were transported from Europe to North America for agricultural and ornamental purposes. Others were transported accidentally by ship, train, airplane - even on the shoes of hikers.
Problems?-
Competitors
Predators
Diseases
d) Climate change-expected to threaten with extinction approximately one quarter or more of all species on land by the year 2050.
Species in the oceans and in fresh water are also at great risk from climate change, especially those that live in ecosystems like coral reefs that are highly sensitive to warming temperatures
Overexploitation- (food, fur, collecting, pest eradication, etc)
Example: Passenger Pigeon
Pollution and contamination
Dead zone in the Gulf of Mexico 5800 square miles created by nutrients used on farmlands traveling down the Mississippi River
Creates low oxygen waters

3) Explain the value of biodiversity. What are the intrinsic and instrumental values of biodiversity?
The Value of Biodiversity are:
Ecosystem capital is the sum of all the foods and services provided to human enterprises by natural systems.
Estimated to be $41 trillion a year.
The basis of most of the natural capital is ecosystems, and the basis of ecosystems is the plants, animals, microbes-the wild species- that make them work.
The reason to care about biodiversity is: Instrumental value- its existence or use benefits some other entity. Instrumental Value of Biodiversity are
Ecosystem sustainability- protection of water resources, nutrient storage and recycling, contribution to climate stability.
Biological resources- food. Most of our food comes from 3 plants.
Animal husbandry- the science of taking care of domestic animals that are used primarily as food or product sources.
Aquaculture- the farming of shellfish, seaweed, and fish
Gene banks- wild species often form a gene bank that can be tapped to improve commercial species
Value as sources for medicines and pharmaceuticals.
Ethical, aesthetic, recreational scientific and cultural reasons.
Recreational and aesthetic activities support commercial interests
Intrinsic value- when something has value for its own sake, it does not have to be useful to us to possess value
Do species other than humans have inherent rights?
4) What is a keystone species? Why does it have such an impact on diversity? Give and discuss an example.

Keystone species- species whose role is absolutely vital to the survival of many other species in an ecosystem
The classic tale of a keystone species is that of the sea otter, which was once found in abundance along the West Coast of North America.

European and Russian trappers hunt sea otters to near extinction in the 18th and 19th centuries.
The decline of the sea otters, which are essential to keeping sea urchins in check, allows sea urchin populations to explode.
The sea urchins feast on and decimate the kelp beds, which are critical habitat for spawning fish. Fish begin to decline for lack of spawning habitat; this affects fishermen's catches.
Finally, an international treaty is enacted to protect sea otters.
In areas where the otters recovered, urchin populations are once again kept down, the kelp beds recover, fish nurseries recover, and fish catches rise again

5) What is an introduced species? How can they be a threat to biodiversity?
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