Population Density

Correct answer: A. Population change is explained by three main demographic components: births, deaths, and migration. A sudden increase in growth rate may occur because the birth rate has risen, the death rate has fallen, more people have moved into the area, fewer residents have moved out, or several of these changes have occurred together. Administration should first compare recent and earlier records for all three components and also check whether the data collection method has changed. B, C, and D do not directly measure population change, so they cannot identify its demographic cause. Memory cue: for a sudden population change, check the three doors—births, deaths, and migration.

The direct answer is A. National population growth is an average or overall change for the country, but local places can experience very different conditions. A city receiving many migrants may grow quickly even when the country’s overall growth is only moderate. Migration can increase the local population and demand for housing, jobs, transport, water, schools, and health services. Option A is correct because it shows why scale and movement of people matter. Option B is wrong because identical rates would not create the stated difference in effect. Option C is not a meaningful example of comparing local growth in an inhabited place. Option D is wrong because the absence of a census creates a measurement problem; it does not itself produce a local-national growth pattern. Also, local change can reflect births, deaths, and migration, while the national total includes movements within the country differently from local areas. Memory cue: national averages can hide strong local gains or losses.

Direct answer: Option B. Actual population growth is found by considering all population-changing components, not births alone. The basic relationship is: actual change = births − deaths + in-migration − out-migration. A high birth rate adds people, while out-migration removes people. For example, if births add 500 people and 700 people leave, the population may fall unless deaths and in-migration compensate for that loss. Option A is wrong because birth rate alone ignores people leaving and may exaggerate growth. Option B is correct because out-migration must be subtracted and the complete balance must be calculated. Option C is wrong because migration cannot be assumed to be zero without evidence. Option D is wrong because death rate measures deaths per population, whereas area measures land size. Memory cue: additions minus losses give the real change; out-migration is a loss.

The direct answer is A: 300 people. Actual growth includes both natural change and migration. Natural increase is births minus deaths: 900 − 500 = 400. Net migration is in-migration minus out-migration: 200 − 300 = −100, meaning 100 more people left than entered. Add the two components: actual growth = 400 + (−100) = 300. The same result comes from the complete formula: births − deaths + in-migration − out-migration = 900 − 500 + 200 − 300 = 300. Option A is correct. Option B ignores migration and gives only natural increase. Option C uses an incorrect combination of the figures. Option D incorrectly treats the movement figures as if they increased the population together. Memory cue: add births and arrivals; subtract deaths and departures.

Direct answer: D is correct. Natural increase means the change produced by births and deaths within a population, without including migration. It is calculated as number of births minus number of deaths during a given period. If births are greater than deaths, natural increase is positive; if deaths are greater, the natural change is negative or a natural decrease. A is wrong because immigration and emigration describe migration, which affects total population change but is not natural increase. B is wrong because area and density describe the spatial relationship between people and land. C is wrong because literacy and sex ratio are population characteristics, not the two components of natural increase. Memory cue: natural increase comes from nature-related population events—births minus deaths; migration is kept separate.

Correct answer: B, 400. Actual growth includes natural increase and net migration. First calculate natural increase: births − deaths = 700 − 400 = 300. Next calculate net migration: in-migration − out-migration = 200 − 100 = 100. Add these two effects: 300 + 100 = 400. In one expression, actual growth = 700 − 400 + 200 − 100 = 400. Option A ignores migration and gives only natural increase. Option C and option D do not follow from the required additions and subtractions. The safe rule is to add births and arrivals, then subtract deaths and departures.

Direct answer: B is the best choice. Population change is determined by two balances: natural change, which compares births with deaths, and migration change, which compares in-migration with out-migration. Deaths reduce the number of residents, while out-migration removes residents from the area. Therefore, if deaths and out-migration are sufficiently high and together exceed births and in-migration, the population decreases. A normally adds people because births and in-migration increase the total. C produces natural increase because births exceed deaths. D produces a positive migration balance because more people enter than leave. Strictly, merely saying that deaths and out-migration are “high” does not guarantee decline unless losses exceed additions, but B is the only option that describes the decreasing forces and is clearly the intended answer. Memory cue: population change = births − deaths + in-migration − out-migration.

The direct answer is A: in-migration adds people to the population. Population change depends on three major components: births, deaths, and migration. A low birth rate means that fewer newborns are being added than before; it does not mean that no people can enter the area. When workers come from another place for employment, they are migrants entering the receiving area. Their arrival can be greater than the reduction caused by low births, so the total population may rise. A is correct because it identifies the effect of in-migration. B is wrong because a low birth rate does not remove people already living there and cannot make the population automatically zero. C is wrong because employment is a common reason for people to migrate. D is wrong because a death rate does not automatically increase merely because outsiders arrive. Memory cue: population change = births − deaths + in-migration − out-migration.

Direct answer: Option A is correct. Population density is the number of people living in a unit of area. It can be understood with the formula: density = population divided by area. To see the effect step by step, first keep the area limited; then add a rapidly growing population. The numerator rises while the denominator remains small, so the number of people per unit area increases strongly. Option A therefore produces the strongest rise in density. Option B may keep density stable or lower it because the area is increasing faster than population. Option C generally lowers density when area is unchanged. Option D provides no settled population on which such a growth effect can operate. Memory cue: density rises when more people occupy the same or smaller amount of space; always compare population with area.

Extremely cold regions may have very low temperatures, frozen ground, heavy snow, and a short growing season. These conditions make farming difficult because crops have less time to mature. Construction and transport may cost more, and everyday activities require additional heating, equipment, and protection. As a result, fewer kinds of work are possible and living expenses may be high, so people are usually spread thinly.

Option C is correct because harsh temperature limits both settlement comfort and economic opportunity. The other choices describe conditions that do not generally explain low density: cold regions do not always have fertile soil, transport is not always easy, and water availability alone does not guarantee settlement. Some cold areas can be populated, but the question asks about the general pattern.