Processes of Population Change

Correct answer: A. When migrants belong to a specific age or gender group

The correct answer is A. Out-migration changes social structure when the people leaving are selected from a particular age or gender group. For example, if mainly young adults leave, the source area may have a different age composition, fewer working-age residents and a larger relative share of children or older people. If mainly one gender leaves, the sex composition can also change. A is correct because it describes selective migration and its wider social effect. B cannot produce an out-migration effect. C concerns births, not selective movement. D describes physical size and does not tell us who leaves. Memory cue: selective migration changes “who remains,” not just “how many remain.”

Correct answer: A. When in-migration and natural increase rapidly expand a city

The correct answer is A. In-migration brings additional people into a city, while natural increase means births exceed deaths. When both processes rapidly expand the urban population, demand for land, housing, water, energy, transport, drainage and waste management can rise quickly. If planning and infrastructure do not keep pace, environmental pressure may become greater. A is correct because it combines two forces of rapid population increase. B describes stability and adequate services, so pressure is less likely to rise rapidly. C has no net natural increase and no migration. D describes a declining population, which generally creates less immediate population pressure, although environmental problems can still exist. Memory cue: rapid growth plus limited resources increases pressure.

Correct answer: A. When birth rate falls but growth continues due to a large young population

The correct answer is A. Population momentum occurs when a large proportion of people are young and entering or moving through the child-bearing ages. Even after the birth rate begins to fall, this large young group can produce many births, so total population may continue to grow for some time. A is correct because it combines a falling birth rate with a youthful age structure. B would produce no natural increase if births and deaths are both zero. C removes the main condition that creates momentum. D suggests that people leaving exceed births, which would tend to reduce population rather than sustain growth. Memory cue: momentum is growth carried forward by the age structure created in the past.

Correct answer: A. Because regions may have different birth, death, and migration rates

Direct answer: A is correct. A national average combines the figures of many different places into one number. This number is useful for seeing the broad national pattern, but it may hide important local differences. For example, one state may have a high birth rate, another may have a low birth rate, and a third may gain many people through in-migration. These different values can balance one another when averaged. As a result, the national figure may look moderate even though a particular district is facing overcrowding, rapid population growth, ageing, or loss of workers. Option A is correct because birth, death, and migration rates vary from region to region. Option B is wrong because averages are useful for comparison, although they do not show the whole picture. Option C is wrong because regions are not identical in their population processes. Option D is wrong because people live in villages, towns, cities, and many regions, not only in the capital. Memory cue: national average gives the broad picture; local data reveals the uneven picture.

Correct answer: A. When in-migration rises rapidly and housing availability is low

Direct answer: A is correct. In-migration means people enter a city from other places. If many people arrive in a short period, the demand for houses, rented rooms, water, sanitation, transport, and jobs can rise quickly. When formal or affordable housing is insufficient, some households may live in temporary or unplanned settlements. This does not mean that every migrant creates a problem; migrants may supply labour and contribute to the city economy. The key point is the mismatch between rapidly increasing demand and limited housing and services. Option A is correct because rapid in-migration combined with low housing availability creates strong housing pressure. Option B is generally unsuitable because a declining population usually reduces, rather than increases, pressure from new residents. Option C is wrong because it removes the migration-related cause described in the question. Option D is wrong because faster-growing health services would improve support and would not itself explain the growth of informal settlements. Memory cue: fast population inflow plus too little housing produces urban housing pressure.

Correct answer: A. Adding components are compared with reducing components

Direct answer: A is correct. Total population change is understood by considering the processes that add people and the processes that remove people from a population. Births add people, and in-migration adds people to a particular area. Deaths reduce the population, and out-migration reduces the population of the place people leave. In simple form, population change can be viewed as births plus in-migration minus deaths minus out-migration. The final result may be positive, zero, or negative, depending on the balance. Option A is correct because it recognises both adding and reducing components. Option B is wrong because births are only one component. Option C is wrong because area helps in studying density but does not by itself calculate population change. Option D is wrong because deaths must be included when measuring change. For example, a place may have many births but still lose population if deaths and out-migration are even greater. Memory cue: add births and arrivals; subtract deaths and departures.

Correct answer: A. When people live longer

Direct answer: A is correct. A fall in the death rate means that, on average, people are surviving for longer, provided other conditions do not reverse the pattern. Over time, more people may reach older ages and remain alive for more years. This can increase the need for services such as healthcare, support for daily activities, accessible transport, social care, and suitable housing. The question is about the effect of longer survival on the age structure of the population, not simply about the number of births. Option A is correct because longer lives can increase the number of elderly people needing support. Option B is wrong because the birth of children is not the direct explanation for increased elderly-service demand. Option C is wrong because stopping in-migration does not itself explain longer survival or ageing. Option D is wrong because a high birth rate mainly increases the child population and does not by itself show that more elderly people are living longer. These effects depend on the wider population structure, so the answer describes a possible demographic relationship rather than an automatic result in every place. Memory cue: lower mortality can mean longer lives and greater ageing-related needs.

Correct answer: A. When a high birth rate rapidly increases the child population

Direct answer: A is correct. A high birth rate can increase the number of children in a population, especially when many births occur over a relatively short period. Children need adequate food, balanced nutrition, healthcare, immunisation, and growth support. Therefore, planners may need to expand food programmes, school meals, maternal and child services, and other forms of nutritional support. Option A is correct because rapid growth in the child population increases the number of people whose nutritional needs must be planned for. Option B is wrong because no births would not create a rapidly growing child population. Option C is less suitable because it describes a declining population with sufficient services, so it does not identify an increased planning pressure. Option D is wrong because a stable population with no migration does not by itself create a new food and nutrition burden. The exact need also depends on existing resources and the health of children, but the demographic pressure in the question is clearly the rise in child numbers. Memory cue: more children require more planned food, nutrition, and care.

Correct answer: A. The destination city receives labour but housing pressure increases

Direct answer: A is correct. Migration can have more than one effect at the same time. A destination city may receive workers who fill jobs, support production, provide services, and contribute to the local economy. At the same time, if housing construction and public services do not keep pace with the additional population, rents, overcrowding, pressure on water and sanitation, and demand for transport may increase. Thus, receiving labour is a possible benefit, while rising housing pressure is a possible cost or challenge. Option A is correct because it explicitly includes both sides. Option B is wrong because no movement means there is no migration effect. Option C is wrong because a fall in death rate is a natural population process, not a pair of migration effects. Option D is wrong for the same reason: a rise in birth rate concerns natural increase, not migration. The actual effects vary by place and by the ability of the destination to plan services, so migration should not be described as entirely good or entirely bad. Memory cue: migration can add workers and add pressure together.

Correct answer: A. When the birth rate is moderate but deaths and out-migration are high

Direct answer: A is correct. Total population does not depend on the birth rate alone. A population can have a moderate or reasonable number of births and still decline if the number of deaths and people leaving the area is greater than the number of births and people entering it. In simple terms, total change equals births plus in-migration minus deaths minus out-migration. In option A, high deaths and high out-migration can make the final balance negative even though the birth rate is not extremely low. Option B is internally unsuitable because if births and deaths are both zero, the population would not decline unless another component, such as out-migration, were present. Option C is likely to increase population, not reduce it, if other factors are unchanged. Option D generally removes one source of decline. The exact result depends on the size of every component, but A is the only option that provides a clear mechanism for decline without requiring a very low birth rate. Memory cue: population can fall because departures and deaths outweigh births and arrivals.

Correct answer: A. When out-migration of the working population weakens the labour and service base

Direct answer: A is correct. The source region is the place from which people leave. If many working-age people move out, the region may lose workers, skills, taxpayers, consumers, and people who provide essential local services. Farms, small businesses, schools, health facilities, and local institutions may then face difficulty maintaining their activities, especially if few replacement workers remain. Regional planning may therefore need to improve employment, education, transport, services, and livelihood opportunities in the source region. Option A is correct because it describes the direct reason for special support there. Option B mainly describes a pressure in the receiving area, not the source area. Option C also refers to the destination city’s service pressure. Option D is a possible benefit in the destination region and does not identify the source region’s weakness. The effects are not identical in every place, because remittances or returning migrants may help the source area, but a weakened labour and service base is a valid reason for targeted support. Memory cue: source region loses people; planning may need to replace lost work and services.

Correct answer: A. When a city has high births, low deaths, and rapid in-migration together

Direct answer: A is correct. Population change is produced by the combined action of natural change and migration. High births add people, low deaths mean fewer people are being removed through mortality, and rapid in-migration adds people from outside. When these three conditions occur together in a city, its total population can grow rapidly, increasing the need for housing, schools, transport, water, health services, and employment. Option A is correct because it includes all three processes and their population-increasing directions. Option B is wrong because an increase in area does not automatically mean that population has changed. Option C is wrong because it removes two important processes and does not describe rapid growth. Option D is wrong because death rate alone cannot show the combined effect of birth rate, death rate, and migration. The actual growth will depend on the numerical size of each component, but A clearly presents the strongest combined growth situation. Memory cue: more births plus fewer deaths plus arrivals produces strong population increase.

Correct answer: A. When natural increase and net migration work in opposite directions

Direct answer: A is correct. Natural increase is the balance between births and deaths, while net migration is the balance between in-migration and out-migration. If natural increase is positive but net migration is negative, or if natural increase is negative while net migration is positive, the two components push the total population in opposite directions. The final result then depends on which effect is larger. A policy based only on one component could therefore be misleading. Option A is correct because opposing components require careful measurement and comparison before planning housing, schools, jobs, healthcare, or other services. Option B is less difficult to interpret because components moving in the same direction and clear data usually make the overall trend easier to identify. Option C removes important processes rather than creating a complex balance. Option D removes migration as a component, so it does not represent the stated analytical difficulty. Memory cue: when demographic forces pull in opposite directions, calculate the net result before making policy.