1)
scientific theory. all but one of the statements below describes some aspect of a scientific theory.
a) once developed, a theory cannot be changed.
b) many observations and much evidence is needed to develop a theory.
c) a theory reflects an understanding of a particular part of the natural world.
d) scientists use the scientific method and controlled experiments to collect evidence to develop a theory.
2)
hypothesis. theory. law. what statements below best apply to a scientific theory. all but one statement could apply.
a) continued observation and research can challenge existing theories.
b) to develop theories, scientists most often rely on an accumulation of knowledge developed over time.
c) a scientific theory is an expression of a mathematical or descriptive relationship observed in nature.
d) a scientific theory may begin with observations and is then substantiated by experimentation and data collection.

Explain how scientists use geologic time to determine the age of landforms.

Archeologists have discovered three sites showing conclusive evidence for the mastery of fire in tanzania, from a period slightly after the time that homo habilis was present in africa. these sites clearly were founded by homo erectus, the descendent species of homo habilis that migrated north, out of africa and into asia. homo erectus was known to have mastered fire, from ample evidence at sites in asia. there is no reason to attribute mastery of fire to homo ergaster, the descendent species of homo habilis that remained in africa.which of the following is an assumption on which the argument depends? (a) before their migration, homo erectus occupied african territory as far south as tanzania.(b) the strain of migration provided the selective pressure motivating homo erectus‘ mastery of fire.(c) homo ergaster would not have derived as much benefit from the mastery of fire as did homo erectus.(d) homo ergaster inherited all cultural knowledge from homo habilis, a species that did not have mastery of fire.(e) homo ergaster did not occupy regions as far south as tanzania until well after the time of these three sites.

The krebs cycle is also known as the calvin cycle pyruvic acid cycle carbon - oxygen cycle citric acid cycle