Symbiosis

Question 1

What is symbiosis?

Answer 1

Symbiosis is an ecological, co-evolved , intimate relationship between organisms of two different species that live in direct contact with one another

Question 2

What are the two categories of symbiosis?

Answer 2

Parasitism

Mutualism

Question 3

Describe parasitism

Answer 3

The parasite gains nutrition and energy

The host is harmed because it loses energy and resources

Effective parasites do not kill their host as they cannot survive without it due to their limited metabolism

Example- headlice

Question 4

Describe mutualism

Answer 4

Where both organisms benefit from the symbiotic relationship

Question 5

Chloroplast and mitochondria example of mutualism

Answer 5

It’s is thought that chloroplasts and mitochondria evolved from small prokaryotes which initially lived inside larger eukaryotic cells

Eukaryote gains food from chloroplast ancestor and more energy from mitochondria ancestor

Prokaryote gains safety and protection

Question 6

Evidence for chloroplast and mitochondria example of mutualism

Answer 6

Mitochondria and chloroplasts contain circular chromosomes like prokaryotes

They have ribosomes more similar to prokaryotes

The way they divide is like bacteria cell division

Question 7

What are the three methods for the transmission of parasites?

Answer 7

Direct contact

Use of vector

Release of resistant stages

Question 8

Describe direct contact as a method of transmitting parasites

Answer 8

Where the parasite is transmitted from one host to another through touch

Question 9

Describe use of vector as a method of transmitting parasites

Answer 9

Where the vector picks up the parasite from one host and delivers it to another

Example- malaria

Question 10

Describe release of resistant stages as a method of transmitting parasites

Answer 10

The parasite is able to survive adverse environmental conditions for long periods of time until they come into contact with a new host

Question 11

How do parasitic life cycles evolve involving a secondary host?

Answer 11

Happens when a new primary host becomes infected when it is invaded by or consumes an infected secondary host

Example- tapeworm can complete its life cycle once it has established itself in secondary host (pig) which is then consumed by primary host (humans)

This way there is no competition from offspring as they will find their own host