Answer:
The correct answer is B. Isotopes of an element differ in the number of neutrons.
Explanation:
Isotopes are atoms of the same chemical element, and therefore with the same number of protons, in which the number of neutrons in the atom core differs. According to current models, an atom consists of an atomic nucleus surrounded by a cloud of electrons. The core consists of a number of protons and a number of neutrons. The number of protons determines the atomic number of the element and also the chemical properties. The number of neutrons determines, among other things, the stability of the nucleus and, together with the number of protons, the atomic mass. Two atoms with the same number of protons but a different number of neutrons are called two isotopes of the same element.
Most macromolecules are polymers of simple molecules (monomers). There is not a great variety of simple molecules, but their structure determines the macromolecule. For example, proteins are macromolecules synthesized from amino acids. There are only 20 amino acids and a great number of proteins made of different combinations of those 20 amino acids.
Answer:
Nitrogen-fixing bacteria are prokaryotic microorganisms that are capable of transforming nitrogen gas from the atmosphere into “fixed nitrogen” compounds, such as ammonia, that are usable by plants.
Explanation:
