Many candidates could not properly identify the specimens namely F. Venus fly trap, G tick and so this affected their responses on the other sub answers. The few candidates who could correctly name the parts lost marks due to spelling errors. A number of candidates could state the function of the bristle on the fly trap and the mouth part of the tick but could not correctly state, the mode of feeding of the specimens, the similarities and differences in the modes of feeding of F and G as well as the biological significance of the mode of feeding of F.
Expected answers include.
Name of parts
I - Bristle/hair like structures IV - Mouth part.
II - Sensitive hair V - Cephalothorax/Prosoma
III - Leaf VI - Abdomen/opisthosoma
6 x ½ ( 3 marks)
Mode of feeding of F & G
F - Insectivorous/Carnivorous/Phorosynthetic
G - Parasitic
Similarity in feeding
Both feed on animals
Differences in mode of feeding
F/Venus fly trap G/Tick
- Two modes of feeding/ - One mode of feeding/parasitic
Carnivorous/Photosynthetic
- Extra cellular digestion - Intra cellular digestion.
Biological significance of mode of feeding in F
- the plant usually grows in places with little/no nitrogenous salts;
- so in addition to photosynthesizing;
- the plant uses insects/small animals;
- as a protein/nitrogenous salts source;
- to make up for this deficiency.
Again many candidates performed poorly at stating two features of F/fly trap G/ tick which adapt to their modes of life, could not properly classify specimen G with reasons or state its effect on animals.
Expected answers include.
Observable adaptive features
F/Venus fly trap
- Presence of bristles/hair-like structures - to detect the presence of insects/sensitive to
touch by insects;
- Trap-like structure - to capture the insects;
- Large surface area of leaves - for trapping of prey/insect/digestion of food.
G/Tick
- Piercing and sucking/sharp pointed - for piercing host skin/sucking blood;
Mouth parts.
- Large abdomen - for storing blood;
- Claws on legs - to hold on to the host/support.
Class of G/Tick
Arachnida
Reasons
- 2 body divisions/possession of cephalothorax and abdomen;
- possession of eight legs/four pairs of legs;
- possession of a pair of pedipalps.
Effects of G/Tick on animals
- loss of weight/retarded growth/loss of blood/anaemia;
- restlessness/uncomfortable/irritation;
- transmission/victor of diseases;
- development of sores on skin;
- loss of hairs around the infested area;
- production of poor hides/skin.