The fertility rate of 2.1 with which populations are expected to eventually stabilize is known as the long-term replacement rate. In other words, if a nation maintains a fertility rate of 2.1 over a long period of time the population of that nation will eventually stabilize and it will neither grow nor shrink. Immigration allows the people to grow faster than the fertility rate would suggest. Also because of past growth, the population is younger than it would otherwise be. This means that there are more potential mothers and fathers. Only after its residents age can the population of a country stabilize.
Lines of longitude and latitude help people in finding locations by making the location easier with accuracy on a globe. For example if you had 90 degrees longitude west and 40 degrees latitude east. The lines in which those two intersect is the location. This makes locating very easy and this is what pilots use to travel to different locations.
Answer:
Inside the air sacs, oxygen moves across paper-thin walls to tiny blood vessels called capillaries and into your blood. A protein called haemoglobin in the red blood cells then carries the oxygen around your body.
Explanation:
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Plicae, villi and microvilli increase the surface area for he absorption of nutrients
