The sodium-potassium pump regulates the amount of sodium and potassium inside of cells, particularly nerve and muscle cells. in this process, an atp is burned, causing three sodium ions to be pumped out and exchanged for two potassium ions, which are pumped in by a membrane protein. both ions go against their concentration gradients. the sodium-potassium pump is an example of question 2 options: a. active transport. b. facilitated diffusion. c. passive transport. d. phagocytosis.

What is a coast of using technology to transport water? a.cities can be built in otherwise uninhabitable areas. b.crops can be irrigated and grown in new areas. c.floods can be averted in flood-prone areas. d.freshwater supplies can be depleted in an area.

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.

Some steps in cell division are shown below: 1. chromosomes condense and pair up 2. segments of dna of sister chromatids twist and cross 3. exchange of dna occurs between chromosomes 4. four daughter cells are created that are haploid which of the following steps is least likely to occur during meiosis 1?