Topic 4 Notes
PLEASE WRITE YOUR ANSWERS IN FULL SENTENCES SO YOUR NOTES MAKE
SENSE WHEN READ ALONE 
4.1 A closer look at variation
Reduction of Biological Diversity
1. What are three things that can cause the reduction of biological diversity?
Habitat intrusion caused by urbanization, farming, and industry. Overhunting, polluting of
ecosystems, extinction of species.
Extinction and Extirpation
1. Explain the difference between extinction and extirpation.
 Extinction is the disappearance of every individual of an entire species from the face of the
planet
 Extirpation is local extinction or disappearance of a species from a certain location
Natural causes of extinction and extirpation
1. What are three causes of natural extinction and extirpation?
Three causes are:
 catastrophic events such as volcanic eruptions, earthquakes and floods
 lack of food (starvation)
 disease
Overspecialization
1. Explain what overspecialization is and how this is a bad thing?
Sometimes an organism has adaptations that suit a narrow range of environmental conditions. If the
environment then changes, that species can be greatly reduced or even become extinct.
2. Think of an organism that is overspecialized and how it is facing problems.
Pandas. Their habitat is shrinking and they only eat bamboo. If they only eat bamboo and bamboo
forests keep shrinking, their numbers in turn shrink as well.
Human causes of extinction and extirpation
1. What are five things that humans do that cause extinction and extirpation of species?
 Clearing of forests for farmland (Brazilian rainforest)
 Expansion of cities
 Overhunting (buffalo, passenger pigeon)
 Building of dams
 Introduce non-native species
 Pesticides application to farmland
 Logging
Introduction of non-native species
1. Explain in detail how introducing non-native species to an ecosystem can cause the extirpation
or extinction of a species?
Introduced species compete with native species for the same resource. Usually introduced species
don’t have any predators so they thrive. If they keep multiplying and native species decline, the
native species end up losing out.
Effects of extinction and extirpation on an ecosystem
1. Explain why extirpation or extinction of a species is bad for biological diversity.
If a species becomes extinct, that alone reduces diversity because that is one less species on Earth. It
in turn is bad for other species that interact with it or that rely on it in the food web.
4.2 Selecting desirable traits
Biotechnology
1. What are four types of biotechnology or artificial selection that humans utilize today and give a brief
explanation of each?
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Cloning – Make identical copies of organisms
Artificial Insemination – artificially joining male and female gametes
In vitro fertilization – male and female gametes can fertilize in a controlled setting
Genetic engineering – directly changing the DNA of an organism
Biotechnology and Society
1. Read the following points for and against the use of biotechnology and tell me which side you support
and why?
Some arguments for:
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Greater production of food especially for developing countries would allow these countries to produce enough food for their
population.
Not just the quantities of the food but also better quality foods are produced.
Less chemicals on crops is better for the environment so for example if cotton can be bred that needs fewer sprays it saves money and
prevents the spray drifting into the neighboring bush land.
Vaccines can be produced in plants for better human health outcomes.
Produce may reach the consumer in better condition with less spoilage.
Arguments against:
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The transgene in the products may cause allergic reactions in people.
Genetically identical plants and animals leads to a loss of biodiversity.
There has not been enough research on the effect of inserting a gene from one species to another.
The new species may escape into the wild populations and super weeds could be formed by the cross-fertilization of wild species and
transgenic species.
Even one gene could cause major changes in an organism.
Business has control of the products being produced and their motive is profit, which may not be in the best interest of the general
population.
Genetic change in a species is increased.
4.3 Reducing our impact on biological diversity
1. What did the Canadian government create in 1995 to help try to better preserve biodiversity in this
country?
Canadian biodiversity strategy
Strategies to conserve biological diversity
2. What are four strategies that we as humans can do to try and reduce our impact on biodiversity?
Briefly explain how each of your answers helps.
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Control the spread and introduction of exotic species – reduce the amount of competition on
natural species.
Conservation of genetic resources – zoos help keep species alive and keeps their genes available
for reproductive purposes
Protected areas – Parks help protect ecosystems and organisms that live in them. Parks protect
a variety of ecosystems.
Resource use policies – Make laws to protect biodiversity
Restoration programs – Make programs to reintroduce endangered species back into the wild.
Breeding programs to raise population of endangered species.