UGC NET Questions (Paper – 1)

An expanding population pyramid has a broad base representing many children and a sharply narrowing top representing fewer elderly people. This pattern signals high fertility and a large youth cohort in the population. It is typical of societies in earlier stages of demographic transition where birth rates remain high and death rates have started to decline. Thus, a wide-based pyramid indicates a youthful, rapidly growing population, as described in option B.

Option A:
Option A is incorrect because low birth and low death rates with an ageing population produce a more rectangular or top-heavy pyramid, not one with a very wide base. Such structures are characteristic of advanced demographic transition, not expansion.

Option B:
Option B is correct since high birth rates ensure many births each year, producing a large base, and improvements in health allow many children to survive into adulthood. The narrow top reflects fewer older persons in relative terms.

Option C:
Option C is incorrect because zero population growth would show relatively similar proportions in successive age groups, giving a more column-shaped pyramid. A wide base contradicts the idea of stable numbers.

Option D:
Option D is incorrect because a declining population with very low fertility would have a narrow base and a relatively larger proportion of older adults. This is the opposite shape of an expanding youthful population.

Public health measures, better nutrition and control of epidemics often reduce death rates quickly. However, cultural and socio-economic factors cause birth rates to remain high for some years. This combination of low mortality and high fertility leads to very high natural increase, called population explosion. Over time, fertility also declines, but the lag creates a phase of fast growth.

Option A:
Option A is incorrect because fertility alone usually does not rise sharply in the transition; mortality change is the main driver of the explosion phase.

Option B:
Option B is correct as it explains how early mortality decline with delayed fertility decline produces rapid growth, especially in developing countries in mid-transition.

Option C:
Option C is incorrect since simultaneous decline in both fertility and mortality would limit growth; there would be no “explosion”.

Option D:
Option D is incorrect because migration plays a relatively smaller role in national-level population explosions compared with vital rates.

Population explosion describes a very rapid and often uncontrolled rise in population. Such growth can intensify pressure on land,water and other resources. It frequently contributes to deforestation,pollution and environmental degradation. Therefore the situation presented in the question is best captured by the term population explosion.

Option A:
Population explosion directly implies that population size is increasing faster than the capacity of the environment and infrastructure to support it. This mismatch leads to overuse of resources and ecological stress. Hence it appropriately summarises the phenomena listed in the stem.

Option B:
Demographic transition refers to a long term shift from high to low birth and death rates. It is a model of population change over time,not specifically a description of rapid overuse of resources. Thus it is not the most accurate answer here.

Option C:
The Green revolution relates to the introduction of high yielding varieties,irrigation and fertilisers to increase agricultural production. Although it had environmental consequences,it is not a term for rapid population growth. Therefore it does not fit the question’s description.

Option D:
Urban renewal is a process of redeveloping deteriorated urban areas. It may change population distribution but is not a synonym for rapid population increase. Hence it is not appropriate for the stem.

In the demographic transition model, the phase where death rates fall rapidly due to improvements in health and sanitation while birth rates remain high is associated with a population explosion. The gap between birth and death rates is greatest, causing very rapid population growth. This leads to increased demand for land, water, energy and other resources, placing heavy pressure on the environment. Therefore, the stage described in option A correctly corresponds to rapid population growth and heightened resource stress.

Option A:
Option A accurately describes the second stage of demographic transition, often called the “early expanding” stage. In this stage, mortality declines but fertility is still high, producing a surge in population. The resulting population pressure can contribute to deforestation, overuse of water and encroachment on marginal lands.

Option B:
Option B is incorrect because when both birth and death rates are high, the population growth rate is relatively low. Although living conditions may be poor, the environmental pressure from population growth is not as intense as in the population explosion stage.

Option C:
Option C is incorrect since a low birth and low death rate stage is usually associated with stabilised population. In this stage, countries often have better technology and institutions to manage environmental impacts more effectively.

Option D:
Option D refers to a potential stage of population decline, where environmental pressure from population growth is not the key issue. While consumption patterns may still cause degradation, the stage does not match the description of rapid population growth.