ECOLOGY
PROPERTIES OF POPULATIONS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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the population reaches 9 billion
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most countries have replacement level fertility rates
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most countries have higher death rates
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the worldwide infant mortality rate increases
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Detailed explanation-1: -PIP: Replacement level fertility is the level of fertility at which a population exactly replaces itself from one generation to the next. In developed countries, replacement level fertility can be taken as requiring an average of 2.1 children per woman.
Detailed explanation-2: -Replacement-level fertility: Total fertility levels of about 2.1 children per woman. This value represents the average number of children a woman would need to have to reproduce herself by bearing a daughter who survives to childbearing age.
Detailed explanation-3: -Population momentum is driven by the increasingly large cohorts of women in the reproductive age bracket. It’s only when both the fertility rate and the number of women level off that population momentum stops. And this is when global population growth will come to an end.
Detailed explanation-4: -The United Nations Population Division defines sub-replacement fertility as any rate below approximately 2.1 children born per woman of childbearing age, but the threshold can be as high as 3.4 in some developing countries because of higher mortality rates.