A Level Biology Practice Exam

What term is used to describe a negatively charged ion?

1. Cation

2. Proton

3. Anion

4. Molecule

The correct answer is: Anion

The term used to describe a negatively charged ion is "anion." Anions are formed when atoms gain one or more electrons, resulting in a net negative charge due to the increase in the number of negatively charged electrons relative to positively charged protons in the nucleus. This is contrasted with cations, which are positively charged ions formed when atoms lose electrons. Understanding the distinction between anions and cations is fundamental in the study of chemistry and biology, as ions play critical roles in various biological processes, such as cellular function and electrolyte balance. The incorrect options reflect different entities; "proton" refers to a positively charged particle within an atom's nucleus, while "molecule" denotes a group of atoms bonded together, which may not necessarily involve charge at all.