8.7.1 The Abiotic and Biotic Components of the Environment (Structured Question 1 & 2)


Question 1:
R, S and T in Figure below show three types of interactions between organisms.


(a)(i)
Name the type of interaction represented by R and S.
(ii) Describe the interaction represented by R.
(b)(i) In the interactions represented by S and T, what terms are used to describe organisms X and Y?
(ii) State one characteristics of organism X that adapts it for the interaction.
(c) The rubber tree in the interaction represented by S dies.
Explain what will happen to organism X.
(d) Saw dust can be used in the interaction represented by T for the commercial cultivation of mushrooms.
Explain how mushrooms can grow on saw dust.



Answer:
(a)(i)
Organism R: Mutualism/ symbiosis
Organism S: Commensalism

(a)(ii)
Nitrogen-fixing bacteria in the root nodules fix nitrogen to form ammonia which is used by the plant while Rhizobium bacteria get shelter from the plant.

(b)(i)
X: Epiphyte
Y: Saprophyte

(b)(ii)
The presence of aerial roots which absorb moisture from the air

(c)
X continues to grow because it photosynthesises.

(d)
Mushrooms grow on dead organic matter.
Mushrooms secrete enzymes which digest the complex organic matter to simple substances.


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