As shown below, parts of human, cat, whale and bat arms have similar bone structures for similar functions. What is the term for this idea?

vestigial structures

homologous structures

analogous structures

adapted structures

Select the word from the list that best fits the definition a system made of 25 satellites

Which of the following factors would not contribute to allopatric speciation? a) a population becomes geographically isolated from the parent population. b) the separated population is small, and genetic drift occurs. c) the isolated population is exposed to different selection pressures than the ancestral population. d) different mutations begin to distinguish the gene pools of the separated populations. e) gene flow between the two populations is extensive.

What materials must dams have to produce electricity, and what must occur?