The optic nerve is the element in the body that allows us to see. And some specific cells will also help us see various shapes and movements.
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Spleen, thymus, lymph nodes
Answer:
Demographic is used to measure natality, mortality, immigration and emigration.
What is demographic?
“It is statistical study of populations especially humans.”
It determines the population size and composition.
It is to measure:
Natality or birth rate- It defines as the number of births in a given time of a population. If natality is higher the population size increases.
Mortality or death rate- It defines as the number of deaths in a given time of a population. An increasing mortality will decrease the population size.
Immigration- The number of individuals moving in a habitat. It increases the population size and composition.
Emigration- The number of individuals moving out from a habitat. It decreases the population size and composition.
The population size and composition will be increase when the sum of natality and immigration is more than the sum of emigration and mortality.
The population size and composition will be decrease when the sum of natality and immigration is less than the sum of emigration and mortality.
Hence, the demographic measures birth rate, death rate, immigration and emigration to determine population size.
Explanation:
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