What is altitude sickness and how does our body recover from this?

Select the statement which explains best parasitism.

• One organism is benefited.

• Both the organisms are benefited.

• One organism is benefited, other is not affected.

• One organism is benefited, other is affected.

75.

Construct an age pyramid which reflects a stable growth status of human population.

Study the graph given below and answer the questions that follow:

(i) Write the status of food and space in the curves (a) and (b).

(ii) In the absence of predators, which one of the two curves would appropriately depict the prey population?

(iii) Time has been shown on X-axis and there is a parallel dotted line above it. Give the significance of this dotted line.

'Analysis of age-pyramids for human population can provide important inputs for long-term planning strategies.' Explain.

Write the equation that helps in deriving the net primary productivity of an ecosystem.

Why the pyramid of energy is always upright? Explain.

Explain mutualism with the help of any two examples. How is it different from commensalism?