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;
(c) (i) Differences between specimens A and B
Specimen A/Larva of Mosquito |
Specimen B/Maggot |
|
mouth brushes are absent; |
|
bristles are absent; |
|
anal gills absent; |
|
anterior end is pointed; |
|
posterior end is blunt/wide;. |
|
absence of antennae; |
|
two body divisions/head and trunk; |
|
has two pairs of spiracles; |
|
hook present; |
|
siphon/breathing trumpet/tube absent; |
|
pad 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.