Question

The data below shows the average number of ticks per animal in a certain farm before and after spraying the animals with a certain chemical. The spraying was done once every month. The data was tabulated as shown below.
 

Time( months)	0	2	4	6	8	10	12	14
Average number of ticks	200	90	40	20	16	25	45	90

1. Plot a graph of ticks against time
2. Account for the shape of the graph between:
   • 0 and 8 months;
   • 10 and 14 months. 
3. From the graph, determine the average number of ticks after spraying the animals for five months. 
4. If the animals were allowed to graze in an open field, construct a food chain with five organisms in which ticks are secondary consumers.
5. State three methods by which the average number of ticks per animal could have been estimated. 

Answer 1

1.  
   
   .
2.   
   • Decrease number of ticks due to the chemical killing them / ticks not yet adapted/ developed resistance
   • Increased number of ticks due to increased resistance
3. 28 ± 2
4. Grass → Animal → Tick → bird → Vulture
5.   
   • Mapping various parts of the animals body
   • Physical counting
   • Sampling the animals