Biology Paper 3 (Practical), WASSCE (PC 2ND), 2022

Question 3

  1. The diagram below is an illustration of organisms in a habitat. Study it and answer questions 3(a) to 3(c).

(a)  (i)   Name the habitat.
[1 mark]
(ii)  Name the trophic level occupied by each of the organisms I, II, III and IV in the habitat.
I:
II:
III:
IV:
                                                                                                            [4 marks]
(iii)  Construct a food chain using the organisms labelled in the diagram.
[5 marks]
(b)  (i)  What is the role of the sun in the habitat?
[3 marks]
(ii)  If the organisms labeled I are present, what would be the effect on the habitat?
[4 marks]
(c)        Name two:
                        (i)         biotic components in the habitat;
(ii)        abiotic components in the habitat.
[4 marks]
(d)        Name the mode of nutrition of each of organisms I, II, III and IV.         [4 marks]
(e)        State two adaptive features of the organisms labelled I to their mode of life in the habitat.
[4 marks]
(f)        Name the part labelled V.                                                                      [1 mark]

Observation

 

Candidates performed fairly in this question. Many of the candidates were able to identify the habitat correctly as a pond and state the trophic level of the labelled organisms.

Many of the candidates were also able to construct a food chain involving the organisms.

The expected answers are:

(a) (i)        Name of habitat
(Fresh water) pond.                                                                                                      
Note:  spellings must be correct to score.

     (ii)   Trophic level of labelled parts
I    -     producer/first/1
II  -      primary consumer/second/quaternary/2
III -      secondary consumer/tertiary/3                                   
IV -      tertiary consumer/quaternary/4                                  

(iii)  Food chain
I/plants           II/tadpole           III/small fish             IV/big fish                                                                  Note:  Any two correct arrows to score one mark.
Position of four organisms to score one mark each.

(b) (i)   Role of the sun in the habitat

  • the sun is a source of solar/light energy;
  • for plants to use to manufacture food/photosynthesis;
  • promotes the growth of plants;
  • keeps the water warm/increase in temperature.                                      

     (ii)   Effect of the absence of the organisms labelled I in the habitat

  • if they are absent, the solar/light energy is not fully utilized/captured;
  • food is not manufactured/ produced for the animal;
  • oxygen is not released into the water;
  • therefore life cannot be sustained;
  • animals find it difficult to breathe;
  • carbon dioxide accumulates;
  • and the environment becomes polluted;
  • eventually all the organisms die.                                                              

(c) (i)   Biotic components in the habitat
            -      Plants/water plants;        
-      Animals/fish/tadpole/mosquito larva(e).

(ii)   Abiotic components in the habitat
-       Water
-        Soil/humus
-        Temperature                                                                                          

(d)       Mode of nutrition of labelled parts
I    -     autotrophic/holophytic/photosynthetic
II  -     herbivorous/holozoic/heterotrophic

III -      carnivorous/holozoic/heterotrophic                            
IV -      carnivorous/holozoic/heterotrophic                                                              

(e)        Adaptive features of the organism labelled I to their mode of life in the habitat

  • Well-developed numerous fibrous root system; for anchorage into mud;
  • Long petiole; raises the leaves above water; for photosynthesis;
  • Numerous root hairs; for absorption of nutrients;
  • Air spaces/spongy tissues; for buoyancy/floating;
  • Broad leaves; enhances absorption of sunlight for photosynthesis;
  • Presence of chlorophyll/chloroplast for photosynthesis.                          

(f)        Name of the part labelled V
Soil/Mud/debris/humus/organic matter/decomposed matter/detritus.