Which of the followinf is not an example of using relative density to measure population density in a certain area ?

Options

A. Counting pugmarks of tigers to find population density to tigers in a forest.
B. Counting the number of fishes caught in a trap to find population density of fishes in a lake
C. Measuring biomass of bacterial culture to find out population density of bacteria in a petri dish.
D. Measuring biomass of phytoplanktons in 1 c c water to find out population density of phytoplanktons in a lake.

Explanation

To determine which of the following is not an example of using relative density to measure population density in a certain area, we can follow these steps:

### Step 1: Understand Relative Density
Relative density is a method of estimating population density without directly counting every individual. It often involves indirect measures that can provide an estimate of population size based on certain indicators.

### Step 2: Analyze Each Option
We will evaluate each option provided to see if it represents a method of measuring relative density.

1. **Counting pug marks of tigers**: This method involves tracking the footprints of tigers to estimate their population. This is a valid example of relative density since it uses indirect evidence to estimate population size.

2. **Counting the number of fishes caught in a trap**: This method estimates fish population by the number caught in traps. This is also a valid example of relative density as it uses a sampling method to infer the total population.

3. **Measuring biomass of bacterial culture**: This method involves measuring the total biomass of bacteria rather than estimating population density through indirect means. This does not fit the definition of relative density since it does not use an indirect measure to estimate population size.

4. **Measuring biomass of phytoplankton in 1 cc of water**: Similar to the bacterial culture, this method measures the biomass directly. However, it can still be used to estimate population density indirectly if the biomass is correlated with population size, but it is less direct than the previous examples.

### Step 3: Identify the Incorrect Example
From the analysis:
- Options 1, 2, and 4 can be considered examples of relative density.
- Option 3 (measuring biomass of bacterial culture) does not fit the criteria for relative density since it does not use an indirect measure to estimate population density.

### Conclusion
The answer to the question is **Option 3: Measuring biomass of the bacterial culture to find out population density of bacteria in a petri dish** is not an example of using relative density.

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