Biology Paper 3 (Practical), WASSCE (SC), 2018

Question 1

 

 

LIST OF SPECIMENS
Specimen A     -           Fresh/wet preserved mosquito larva in a Petri dish containing water.
Specimen B     -           Fresh/wet preserved maggot in a Petri dish containing water.
Specimen C     -           Gill of fish (freshly procured) in a Petri dish containing water.
Specimen D     -           Lung of a small mammal (freshly preserved).
Specimen E     -           Dicotyledonous leaf (freshly plucked).
Specimen F     -           Membranous wing of a Cockroach.
Specimen K    -           Flower of Pride f Barbados or Caesalpinia.
Specimen L     -           Mature Elephant grass or Guinea grass.

Specimen M    -           Flower of Hibiscus plant.

 

1. Study specimens A and B and answer questions 1(a) to 1 (c).
(a)(i) Name the habitat of each of specimens A and B.                  [2 marks]
(ii) Name the adult stage into which each of specimens A and B would develop.               [2 marks]
(iii) Name the phylum and class common to the adult stages of specimens A and B.             [2 marks]
(b)  State three observable features of biological significance in:
(i)   Specimen A;                                                         [6 marks]
(ii)  Specimen B.                                                         [6 marks]

(c)(i) State four observable structural differences between specimens A and B. [4 marks]
(ii)  State three observable similarities between specimens A and B.[3 marks]

Observation

Some candidates could not spell the term ‘Arthropoda’ correctly.
In 1 (a) (i), some candidates wrote ‘aquatic’ or ‘terrestrial’ respectively. These answers were too wide and made them lose marks. Majority of the candidates could state the adult stages of specimens A and B and name the phylum and class of the specimens but some could not spell correctly in questions (a) (ii) and (iii), some could also not start the taxonomic names with a capital letter which also made them miss the marks.

In 1 (b), some candidates overlooked what was asked about structural significance and went on to enumerate functions and features, also some candidates did not relate structures with functions.

In 1 (c) (i) and (ii), some candidates’ responses were not encouraging at all.

The expected answers are:

(a)        (i)  Habitats of
Specimen A/Larva of Mosquito
Stagnant water/swampy areas/pool/pond/edge of stream/any correctly named habitat.                                                                                                                   
Specimen B/Maggot
Rotting/rotten/decaying/decomposing animals/decaying food/human faeces/pit latrine/any correctly named habitat.                                                                 

(ii) Adult stage of
Specimen A/Larva of Mosquito
Mosquito/Anopheles mosquito/Culex mosquito/Aedes mosquito.

Specimen B/Maggot
Housefly/ Musca domestica                                                                     

(iii) Phylum and Class common to Specimens A and B
Phylum
Arthropoda                                                                                              

Class
Insecta                                                                                                      

(b) Observable features of biological significance in
(i) Specimen A/Larva of Mosquito

  • Presence of spiracles; for breathing/gaseous exchange;
  • Presence of siphon/breathing trumpet/breathing tube; for breathing/gaseous exchange;
  • Presence of antennae; for sensitivity;
  • Horny jaw/mouth; for chewing solid foods;
  • Mouth brushes; for sweeping food into its mouth;
  • Presence of bristles; to remain afloat/buoyancy/protection/defence;
  • Feather-like/feathery hair; for defence;
  • Long/cylindrical body; for wriggling movement;
  • Presence of eyes; for vision/sight/seeing.                                  

(ii) Specimen B/Maggot

  • Hook at the mouth; for movement/tearing of food/feeding;
  • (Small) spiny pad; for movement;
  • (Small) mouth; for feeding;
(Two pairs) of spiracles; for breathing/gaseous exchange.

(c) (i) Differences between specimens A and B


Specimen A/Larva of Mosquito

Specimen B/Maggot

  • Mouth brushes present

mouth brushes are absent;

  • Bristles present

bristles are absent;

  • Anal gills present

anal gills absent;

  • Anterior end not pointed

anterior end is pointed;

  • Posterior end not blunt/wide

posterior end is blunt/wide;.

  • Has antennae

absence of antennae;

  • Three body divisions/head, thorax,abdomen

two body divisions/head and trunk;

  • Has one spiracle

has two pairs of spiracles;

  • Hook absent

hook present;

  • Siphon/breathing trumpet/tube present

siphon/breathing trumpet/tube absent;

  • Pad absent

pad present.

  • Eye present

eye absent

 (ii) Similarities between specimens A and B

  • They both have segmented body;
  • They both possess spiracle;
  • They both have mouth;
  • Both have elongated/long body/cylindrical.