Because the older cells will not be able to function properly without the new cells taking over them. :)
Answer:
Threatened Species: A threatened species is a species at risk but not yet endangered. California sea otters were classififed as a threatened species. Laws were passed to protect the otters and now they have increased their population size.
Invasive Species: One of the main causes of extinction and endangered species is the introduction of an exotic species. New exotic species are called invasive species. Invasive species can disrupt food chains, carry disease, prey on native species directly, and out-compete native species for limited resources, like food.
Extinction: If a population decreases too much in numbers, they disappear. Extinct species mean that the species has died out and no individuals left. An example of extinction: New Zealand was once home to a bird called the Giant Moa. Humans settled as their population increased the Moa population decreased. The species is now extinct.
Explanation:
The average atomic mass of Boron: 10.431 amu
<h3>Further explanation
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Isotopes are atoms whose no-atom has the same number of protons while still having a different number of neutrons.
So Isotopes are elements that have the same Atomic Number (Proton)
Atomic mass is the average atomic mass of all its isotopes
In determining the mass of an atom, as a standard is the mass of 1 carbon-12 atom whose mass is 12 amu
Mass atom X = mass isotope 1 . % + mass isotope 2.% + ...
The average atomic mass of boron :

Answer: Small groups of atoms that are attached to larger molecules, giving the specific chemical properties, are called functional groups.
explanation: Functional groups are groups of atoms in a molecule that possess the same chemical feature every time it appears in several compounds. There are various types of functional groups and they have the tendency to react in definite ways. Examples include; the ether functional group (consists of an oxygen atom that forms single bonds with two carbon atoms),the alcohol functional group (consists of an oxygen atom that is bonded to one hydrogen atom and one carbon atom), and the amine functional group (consists of a nitrogen atom bonded to some combination of carbons and hydrogens).