This question was popular among candidates, majority of the candidates attempted it and performed fairly well.
In part (a)(ii) candidates were not able to describe features of each of the labelled stages.
The expected answers were as follows:
I Egg - Possesses floats/air cells
- Spherical/streamlined in shape.
II Larva - Possession of spiracle which is used for breathing
- Body divided into segment
- Hair float – which help in catching food.
III Pupa - Breathing trumpet/tube which touch the surface of water
- Free abdomen – the abdomen is free from the body
- Compound eyes, a rounded head and thorax – these developed
more than other stages above
- Developing limps – Limbs in a developed stage
- The body parts like rounded head, thorax and a long curved
abdomen makes it look like a printed comma.
IV Imago/Adult mosquito
- Wings for flight
- Possession of proboscis for sucking of blood/nectar
- Possession of antenna
- Body divided into three segment.