5. Acids, bases, and salts
are three classes of compounds that form ions in water solutions. As a basis
for understanding this concept:
a. Students know the
observable properties of acids, bases, and salt solutions.
b. Students know acids
are hydrogen-ion-donating and bases are hydrogen-ion-accepting substances.
c. Students know strong
acids and bases fully dissociate and weak acids and bases partially dissociate.
6. Stability in an ecosystem
is a balance between competing effects. As a basis for understanding this
concept:
a. Students know biodiversity
is the sum total of different kinds of organisms and is affected by alterations
of habitats.
b. Students know how
to analyze changes in an ecosystem resulting from changes in climate, human
activity, introduction of nonnative species, or changes in population size.
c. Students know how
fluctuations in population size in an ecosystem are deter-mined by the relative
rates of birth, immigration, emigration, and death.
d. Students know how water,
carbon, and nitrogen cycle between abiotic resources and organic matter in the
ecosystem and how oxygen cycles through photosynthesis and respiration.
e. Students know a
vital part of an ecosystem is the stability of its producers and decomposers.
f. Students know at
each link in a food web some energy is stored in newly made structures but much
energy is dissipated into the environment as heat. This dissipation may be
represented in an energy pyramid.
8. Evolution is the result of
genetic changes that occur in constantly changing environments. As a basis for
understanding this concept:
a. Students know how
natural selection determines the differential survival of groups of organisms.
b. Students know a
great diversity of species increases the chance that at least some organisms
survive major changes in the environment.
e. Students know how to analyze fossil evidence with regard to
biological diversity, episodic speciation, and mass extinction.