H Biology - Unit 3 - KA5 - Symbiosis

What is symbiosis?

Symbiosis is an intimate co-evolved relationship between members of two different species

What are the two types of symbiotic relationships?

The two types of symbiotic relationships are;

• Mutualism

• Parasitism

What is mutualism?

Mutualism is a symbiotic relationship where both partner species benefit. The benefit is usually in terms of gaining energy or nutrition.

What are examples of mutualistic relationships?

Examples of mutualistic relationships are;

• Cellulose digesting bacteria in herbivores guts

• Cleaner fish cleaning sharks

• Fungus and algae or cyanobacteria in lichen

• Leguminous plants relationship with rhizobia bacteria

What is parasitism?

Parasitism is a symbiotic relationship between a host and parasite. The parasite benefits in terms of energy or nutrients and the host is harmed by the loss of these resources.

What are examples of parasites?

Examples of parasites are;

• Head lice

• Ticks

• Tapeworms

What are the three ways parasites can be transmitted?

The three ways parasites can be transmitted are by;

• Direct contact

• Vectors

• Resistant stage

What is direct contact in terms of transmission of parasites?

Transmission through direct contact is physical contact that passes parasites from one host to another. For example, headlice.

What is a vector?

A vector is an organism that directly carries and transmits a parasite into it’s host.

Is water a vector?

Water is not a vector

What is an example of a vector?

An example of a vector is the Anopheles mosquito. Mosquitoes are the vector for the malaria parasite which is carried in their saliva. When the mosquito bites, the plasmodium parasite is transmitted into the host’s bloodstream.

What are resistant stages?

Resistant stages are stages that allow a parasite to survive adverse environmental conditions until they come into contact with their specific host.

What is an example of a parasite that has a resistant stage?

An example of a parasite that has a resistant stage are fleas who can survive as resistant larva or pupa for several months.

In the pork tapeworms life cycle what are the primary and secondary hosts?

In the pork tapeworms life cycle the primary host is the human and the secondary host is the pig.

What is a secondary host?

A secondary host, or an intermediate host, is a host that allows the parasite to complete their life cycle.

Why can parasites not survive out of contact with the host?

Parasites cannot survive out of contact with the host because they have a limited metabolism.

What is an example of a parasite with a limited metabolism?

An example of a parasite with a limited metabolism is the tapeworm. Tapeworms do not have a digestive system because they live in their host’s intestine.