Topic 3_2

Front

Symbiosis is an ecological relationship in which two species (or organisms) live in close contact.

Back

Symbiosis refers to a close ecological relationship between two species or organisms.

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Either partner in a symbiotic relationship is called a symbiont.

Back

A symbiont is one of the partners in a symbiotic relationship.

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The larger symbiont in a symbiotic relationship is often referred to as the host.

Back

In a symbiotic relationship, the larger organism is typically called the host.

Front

Diagram of a symbiont and host relationship.

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The diagram illustrates the relationship between a symbiont and its host in a symbiotic interaction.

Front

Symbiosis involves interactions between two organisms where at least one benefits.

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Types of symbiosis include Mutualism, Parasitism, Commensalism, Amensalism, and Competition. Mutualism is when both organisms benefit (+, +), Parasitism is when one benefits and the other is harmed (+, -), Commensalism is when one benefits and the other is unaffected (+, 0), Amensalism is when one is harmed and the other is unaffected (-, 0), and Competition is when both are harmed (-, -).

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Mutualism is a type of symbiosis where both organisms benefit.

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Examples of mutualism include bees pollinating flowers while obtaining nectar, cleaner fish removing parasites from larger fish, and microbes in cow guts aiding digestion.

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In parasitism, one symbiont (parasite) benefits at the expense of the other (the host).

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Parasitism is a relationship where one organism (the parasite) benefits while harming the host.

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Parasites that cause disease are called pathogens.

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Pathogens are parasites that lead to diseases in their hosts.

Front

The spiral bacterium that causes Lyme disease is called Borrelia.

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Borrelia is the spiral-shaped bacterium responsible for Lyme disease, which is transmitted by ticks.

Front

Some pathogens use toxins to cause disease.

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Certain pathogens produce toxins that harm the host and lead to diseases.