Astudent measures the range of sound frequencies that the human ear can hear by playing sounds for volunteers between 10 and 30,000 hertz and asking them to raise their hand if they were able to hear it. what type of variable is the independent variable in this experiment?

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.

9. technology can bring both good and bad things. building a vertical farm can increase food supplies in cities (good), but it may cause unemployment in rural areas (bad). give another example of both the good and bad sides of a technological advancement (5 noints)

Chitin is a chemical component of the cell walls