(a) Explain the terms: (i) Parasitism (ii) Commensalism (b) Mention: (i) one fungal parasite of a plant and its host (ii) one bacterial parasite of humans. ...

(a) Explanation of terms

• (i) Parasitism: An association between two organisms of different species in which one (the parasite) lives on or inside the other (the host), obtaining food and shelter from it and harming the host in the process. For example a tapeworm in the human intestine.
• (ii) Commensalism: An association between two organisms of different species in which one (the commensal) benefits (usually for food or shelter) while the other (the host) is neither harmed nor benefited. For example the remora fish attached to a shark, or epiphytes growing on a tree.

(b) Named parasites and hosts

• (i) A fungal parasite of a plant and its host: Puccinia (rust fungus) on wheat/cereal (also acceptable: Phytophthora on Irish potato).
• (ii) A bacterial parasite of humans: Vibrio cholerae (causing cholera) (also acceptable: Mycobacterium tuberculosis, Salmonella typhi).

(c)(i) Four symptoms of malaria

1. High fever with intermittent chills and shivering.
2. Headache.
3. Body/joint pains and general weakness.
4. Sweating, loss of appetite and sometimes vomiting.

(c)(ii) Six methods of controlling malaria in West Africa

1. Clearing bushes and draining/filling stagnant water to destroy mosquito breeding sites.
2. Spraying breeding waters with oil or larvicides to kill mosquito larvae.
3. Sleeping under insecticide-treated mosquito nets.
4. Using insecticides and mosquito repellents, and screening windows and doors with wire gauze.
5. Introducing larva-eating fish (for example Gambusia/Tilapia) into ponds (biological control).
6. Taking anti-malarial drugs and seeking prompt treatment; and public health education.