QUESTION 3
Relationships I, II, III, IV and V exist among some organisms in an ecosystem. Use them to answer questions 3(a) to 3(e).
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 J a disease.
a. Name the type of relationship in I, II, III, IV and V [5 marks]
b. In relationship IV, what is the biological term for each of organisms B and G?
- B;
- G: [2 marks]
c. Name one example each of organisms B to J. [8 marks]
d .(i) Name the relationship that is most beneficial to the ecosystem. [1 mark]
(ii) Give one reason for the answer in 3(d)(i). [1 mark]
e. (i) Give two examples of organism A. [2 marks]
(ii) Name the group to which organism A belongs. [1 mark]
This question was popular among candidates and many did well in it. Some candidates however gave wrong responses to the feeding relationship I and V in question 3(a) by writing Saprophytic, Parasitic etc. instead of Saprophytism and Parasitism respectively.
The biological term for organisms B and G as well as their examples as required in questions 3(b)(i) and (ii) was correctly given by most candidates.
Many candidates could not give the correct name for organisms C, D, E and F in question 3(c).
Spelling mistakes made some candidates perform poorly in this question.
The expected answers are as follows:
(a) Types of relationship
I: Saprophytism
II: Commensalism
III: Mutualism
IV: Predation
V: Parasitism
(b) Biological term for organisms B and G
B - prey
G - predator
(c) Example of organisms B to J
B: Antelope/goat/sheep/cow/rabbit/guinea pig/rat/any other correctly named prey.
C: Remora fish
D: Shark
E: Hermit crab
F: Sea anemone
G: Lion/tiger/leopard/cat/dog/snake /hawk/eagle/any other correctly named predator.
H: Tapeworm/tick/louse/Plasmodium/Ascaris
J: Human/pig/cattle/cow/sheep/dog/cat
(d) (i) Most beneficial relationship to the ecosystem
Saprophytism
(ii) Reason for answer
It is involved in nutrient recycling/replenishment of nutrients in the ecosystem.
(e) (i) Examples of organism A
- Mushroom/Mucor/Rhizopus/Yeast;
- Pseudomonas/Bacillus/Clostridium/Enterobacter/Escherichia spp./E. coli/Salmonella spp.
(ii) Group to which organism A belongs
Fungi/Bacteria/mold/mould