DAT Ch2 Bio Flashcards
(18 cards)
What are the four elements that make up ~96% of living matter?
Oxygen, Carbon, Hydrogen, Nitrogen
What is a trace element?
An element required by an organism in minute amounts (e.g., iron, iodine).
What is the smallest unit of matter that retains properties of an element?
An atom
What are the three subatomic particles and their charges?
Proton (+), Neutron (0), Electron (–)
What is the atomic number?
The number of protons in an atom
What is the mass number?
Protons + Neutrons
What is an isotope?
Atoms of the same element with different numbers of neutrons
What is a radioactive isotope used for in biology?
Tracers in medicine and radiometric dating of fossils
What determines an atom’s chemical behavior?
The number of valence electrons (in the outer shell)
What is a covalent bond?
A bond formed by sharing electrons between atoms
What’s the difference between polar and nonpolar covalent bonds?
Polar = unequal sharing; Nonpolar = equal sharing of electrons
What is an ionic bond?
An attraction between oppositely charged ions formed by electron transfer
What is a hydrogen bond?
A weak attraction between a partially positive hydrogen and a negative atom (usually O or N)
What are Van der Waals interactions?
Weak, temporary attractions due to shifting electron clouds
Why is molecular shape important in biology?
It determines how molecules recognize and bind to each other (e.g., hormones, enzymes)
What happens in a chemical reaction?
Bonds are broken and/or formed; atoms are rearranged
What is chemical equilibrium?
The point at which forward and reverse reactions occur at the same rate
What is the law of conservation of mass?
Matter is not created or destroyed in a chemical reaction
