Question

The diagram below shows the structure of a gill of a bony fish.

1. Name the structure labeled Q, R and S. (3mks)
2. State the function of structure Q, R and S. (3mks)
3. Give four ways in which structure Q is adapted to its functions. 

Answer 1

1.  
   1. Q – Gill filaments
   2. R – Gill rakers
   3. S – Gill bar
2.  
   1. Q ;- Gill filament – provide large surface are for gaseous exchange.
   2. R ;- Gill rakers – Trap food and solid particles to prevent them from damaging delicate gill filament.
   3. S ;- Gill bar – for attachment of gill filaments and gill rakers.
3.  
   1. Numerous to provide large surface area for gaseous exchange.
   2. Thin epithelium to provide a short distance for diffusion of molecules.
   3. Highly vascularised to create a steep concentration gradient for gaseous exchange.
   4. Moist to dissolve gaseous for easier diffusion in solution form.