Ch 5. Symbiosis Flashcards
What is Symbiosis?
An ecological relationship between organisms of two different species that live in direct contact with one another. Theses are intimate relationships that have co-evolved over millions of years.
Name the two types of symbiosis.
- Mutualism
2. Parasitism
What is Parasitism?
A relationship where one species benefits at the expense of the other.
How does Parasitism occur?
The parasite derives its nutrition from another organism, the host, which it exploits.
How is the host affected during/after parasitism?
The host is always exploited to some degree.
It can be harmed, or at least lose some energy/materials to the parasite.
Sometimes the hosts health is impaired slowly, allowing the parasite to exploit its host over a longer period of time.
Why can’t parasites survive well outside of the hosts body?
Give an example of this.
Because of their limited metabolism.
e.g. Tapeworms do not have a digestive system since the host has already digested the food.
What is an endoparasite?
A parasite which lives inside the host.
What is an ectoparasite?
A parasite which lives outside the host.
Give three examples of parasites.
- Fleas
- Ticks
- Tapeworms
Name three ways in which parasites can be transmitted to their host.
- Direct Contact
- Resistant Stages
- Use of a Vector
What is direct contact?
Give an example.
When the parasite is transmitted from person to person by physical contact e.g. head lice.
What are Resistant stages?
A part of the parasite’s life cycle where they are resistant to adverse environmental conditions and can survive for long periods of time, until they come into contact with a new host.
Give an example of a parasite which uses Resistant stages to pass from host to host and describe how this occurs.
The human tapeworm (which can be contracted from pork).
- The pig becomes infected by ingesting tapeworm eggs.
- Once inside the intestine, the eggs release the first stage larvae.
- These then migrate to the muscles, where it develops into a cyst-like structure.
- The cyst can survive for several years in the tissue of the pig (this is the resistant stage).
- When humans become infected by tapeworms they can suffer from symptoms such as stomach pains, vomiting and weight loss.
What is a vector?
A vector is a carrier which allows a parasite to pass from one host to another.
Give an example of a vector.
The mosquito - carries the Plasmodium protoza (causes malaria) from human to human.