Home Board Paper Solutions Text Book Solutions Articles NCERT Exemplar Solutions

Class 12th Biology 2015 Set1 Delhi Board Paper Solution

Question 26

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


Describe the advantages for keeping the ecosystems healthy.


Analysis of age pyramids for human population can provide important inputs for long-term planning strategies. The different age groups present in a population determine its reproductive status.

Distribution of age groups highly influences the growth of the population. Each population displays following three ecological ages or age groups:

Pre-reproductive Reproductive Post-reproductive

Population having large number of young members grow rapidly, while, the population bearing more number of post-reproductive members tends to be declining. There are basically three types of age pyramids found to be present in human population. These are as follows:


Therefore, through the thorough analysis of the age pyramids of a particular population, the distribution of resources can be done more efficiently. A better planning strategy can be adopted considering the demand of the resource; thus, long-term management of resources can be done in such a way that the population can derive maximum benefit with minimum effects on nature, leading the population to flourish efficiently.




The various advantages of keeping the ecosystems healthy are as follows:

Healthy ecosystem is the base for a wide range of economic, environmental and aesthetic goods and services. The products of ecosystem processes are named as ecosystem services, as they are of great help to the organisms living within an ecosystem. Healthy forest ecosystem purify air and water. It also mitigates droughts and floods and cycle nutrients. Healthy ecosystem generates fertile soil and provides wildlife habitat. Maintenance of biodiversity is also an important aspect of healthy ecosystem. It also provides aesthetic, cultural and spiritual values.