a. Draw a pyramid of numbers of a situation ,where a large population of insects

feed upon a very big tree. The insects in turn are eaten by small birds, which

in turn are fed upon by big birds.

b) Differentiate giving reasons between the pyramid of energy of the above and the pyramid of number that you have drawn.

Answer a)

The pyramid of number will be as follows:

Answer b)

The pyramid of energy for the given situation will be like:

The difference in shapes of the two pyramids is because in the pyramid of energy, energy is lost at every step of the food chain. So, the successive trophic level will always have less energy as compared to the previous level, hence a pyramid of energy can never be inverted. But in the case of pyramid of number, only the number of organisms is taken into account and not the size and biomass, so it can take up any shape.