Which of the following is an example of a parasitic relationship?

1. A bee collecting nectar from a flower .
2. A tapeworm living in a human intestine.
3. Egrets following cattle, feeding on the insects.
4. A bird eating berries from a bush.

Which of the following relationships is an example of parasitism?

1. A cleaner wrasse removing parasites from a larger fish.
2. A lichen formed by a fungus and an alga growing together on a rock.
3. An orchid growing on the branch of a rainforest tree without harming it.
4. A cuckoo laying its eggs in another bird's nest for the host to raise.

Commensalism is a form of symbiotic relationship. Which of the following best describes a commensal relationship between two organisms?

1. Both organisms benefit from the interaction.
2. One organism benefits while the other is unaffected.
3. One organism benefits at the expense of the other.
4. Neither organism is affected by the interaction.

Describe the differences between mutualistic and parasitic symbiotic relationships in ecosystems. In your answer, provide one specific example of each type of relationship from nature.   (3 marks)

During their lifetime, plants are exposed to both pathogenic and beneficial microorganisms. Some plants provide shelter within their bodies for beneficial microorganisms.

These beneficial microorganisms help plants that have not been genetically modified to resist pathogenic microorganisms.

The beneficial microorganisms may be providing protection by

1. Synthesising toxins that kill pathogenic microorganisms.
2. Providing a permeable physical barrier to pathogenic microorganisms.
3. Stimulating the production of antibodies against pathogenic microorganisms.
4. Mobilising the cells of the third line of defence against pathogenic microorganisms.

Explain ONE example of a mutual symbiotic relationship.   (3 marks)

A tapeworm is an animal that gains it's nutrients while living inside the host, often making the host seriously ill.

What kind of symbiotic relationship is this an example of?

1. Predation.
2. Parasitism.
3. Mutualism.
4. Commensalism.