BIO 103 FINAL EXAM REVIEW
Characteristics of Life
Living things are made of cells, use energy (metabolism), maintain homeostasis (stable internal
conditions), grow and develop, reproduce, respond to stimuli, and evolve over time
Homeostasis
The ability to maintain stable internal conditions despite external changes (ex: body temperature
regulation)
Sexual Reproduction
Involves two parents; combines genetic material → increases genetic variation
Asexual Reproduction
One parent; produces genetically identical offspring (clones)
Levels of Organization
Atom → Molecule → Organelle → Cell → Tissue → Organ → Organ System → Organism
Atom
Smallest unit of an element that retains its properties
Proton
Positively charged particle located in nucleus; determines element identity
Neutron
Neutral particle in nucleus; adds mass and stability
Electron
Negatively charged particle in electron cloud; involved in bonding
Atomic Number
Number of protons (also equals electrons in neutral atom)
Atomic Mass
, Total number of protons + neutrons
How to Find Neutrons
Atomic mass − atomic number
Isotope
Same element, different number of neutrons (different mass)
Ion
Atom that has gained or lost electrons (charged)
Covalent Bond
Atoms share electrons; strong bond (ex: water)
Ionic Bond
Electrons transferred; forms charged ions (ex: NaCl)
Hydrogen Bond
Weak attraction between slightly charged molecules (important in water & DNA)
Hydrophilic
Polar; interacts with water (ex: sugars, salts)
Hydrophobic
Nonpolar; repels water (ex: lipids, oils)
Acid
Releases H⁺ ions; pH < 7
Base
Accepts H⁺ ions; pH > 7
Buffer
Stabilizes pH by neutralizing acids/bases
pH Scale
0-14; 7 neutral, <7 acidic, >7 basic
Characteristics of Life
Living things are made of cells, use energy (metabolism), maintain homeostasis (stable internal
conditions), grow and develop, reproduce, respond to stimuli, and evolve over time
Homeostasis
The ability to maintain stable internal conditions despite external changes (ex: body temperature
regulation)
Sexual Reproduction
Involves two parents; combines genetic material → increases genetic variation
Asexual Reproduction
One parent; produces genetically identical offspring (clones)
Levels of Organization
Atom → Molecule → Organelle → Cell → Tissue → Organ → Organ System → Organism
Atom
Smallest unit of an element that retains its properties
Proton
Positively charged particle located in nucleus; determines element identity
Neutron
Neutral particle in nucleus; adds mass and stability
Electron
Negatively charged particle in electron cloud; involved in bonding
Atomic Number
Number of protons (also equals electrons in neutral atom)
Atomic Mass
, Total number of protons + neutrons
How to Find Neutrons
Atomic mass − atomic number
Isotope
Same element, different number of neutrons (different mass)
Ion
Atom that has gained or lost electrons (charged)
Covalent Bond
Atoms share electrons; strong bond (ex: water)
Ionic Bond
Electrons transferred; forms charged ions (ex: NaCl)
Hydrogen Bond
Weak attraction between slightly charged molecules (important in water & DNA)
Hydrophilic
Polar; interacts with water (ex: sugars, salts)
Hydrophobic
Nonpolar; repels water (ex: lipids, oils)
Acid
Releases H⁺ ions; pH < 7
Base
Accepts H⁺ ions; pH > 7
Buffer
Stabilizes pH by neutralizing acids/bases
pH Scale
0-14; 7 neutral, <7 acidic, >7 basic
