Theory question 103
Ecological AssociationsRelationships I, II, III, IV and V exist among some organisms in an ecosystem.
I: Organism A grows on dead organism B.
II: Organism C feeds on the remnants of food left by organism D without affecting organism D negatively or positively.
III: Organism E provides shelter for organism F while organism F transports organism E towards food.
IV: Organism G kills organism B for food.
V: Organism H feeds on organism J, causing organism J a disease.
Use them to answer questions 3(a) to 3(e).
(a) Name the type of relationship in: I, II, III, IV, V.
(b) In relationship IV, what is the biological term for each of organisms B and G? (i) B; (ii) G.
(c) Name one example each of organisms B to J.
(d)(i) Name the relationship that is most beneficial to the ecosystem.
(ii) Give one reason for the answer in 3(d)(i).
(e)(i) Give two examples of organism A.
(ii) Name the group to which organism A belongs.
Show the model answer
(a) I saprophytism; II commensalism; III mutualism (symbiosis); IV predation; V parasitism.
(b)(i) B - prey; (ii) G - predator.
(c) B: antelope/goat/rabbit (any prey animal); C: remora fish (or cattle egret on leftovers); D: shark; E: sea anemone; F: hermit crab; G: lion/hawk/leopard; H: tapeworm/tick/Plasmodium/Ascaris; J: man/cattle/dog (host).
(d)(i) Saprophytism (relationship I).
(ii) Saprophytes decompose dead organisms and return mineral nutrients to the soil (nutrient recycling), and they clear away dead bodies.
(e)(i) Any two: mushroom, Mucor, Rhizopus, bread mould, decay bacteria (e.g. Bacillus).
(ii) Decomposers - fungi or bacteria (saprophytes).
Examples in (c) must fit each relationship: E and F, for instance, must be a pair that really live in mutualism.