Principles of Environmental Science Study Set 3
Quiz 5 :
Biomes and Biodiversity
Life expectancy: Explanation The mean age of a newborn infant, which is expected to live in a society, is known as Life expectancy. Life span: The species of oldest age survived by the particular species is known as Life span. Difference between life expectancy and life span includes the following: 1. Life expectancy is defined as an average age of newborn infant that is expected to attain in any society. In contrast, life span is defined as the oldest age to which a species is known to survive. 2. Life span includes maximum age possible by any person in a population, whereas life expectancy is the average age at death of everyone in a population. 3. Life expectancy in most societies probably has been 35 to 40 years, while the oldest age means Life span that can be certified by written records was 122 years.
Extinction: Extinction is a normal process of the elimination of a species from the natural world. Extinctions have occurred in the past, but human involvement has improved the extinction rate by senseless amounts. During the evolutionary change, species die out and are replaced by other species. In a healthy ecosystem the velocity of extinction, looks to be about one species lost every decade. Over the past century, though, human effects on populations and ecosystems have accelerated that velocity, perhaps causing untold thousands of species, subspecies, and varieties to become extinct every year. Extinctions are common in the past. Studies of the fossil record advice that more than 99 % different types of species that are existed in the past are faced exaction. Most of the ancient species are extended before the origin of human race.