The centromere is a region in which a. chromatids remain attached to one another until anaphase. b. metaphase chromosomes become aligned at the metaphase plate. c. chromosomes are grouped during telophase. d. the nucleus is located prior to mitosis. e. new spindle microtubules form at either end.

humans can cause extinction of a species through overharvesting, pollution, habitat destruction, introduction of invasive species (such as new predators and food competitors), overhunting, and other influences. explosive, unsustainable human population growth is an essential cause of the extinction crisis.

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a tetrad is the foursome during meiosis made by two homologous chromosomes that have each already replicated into a pair of sister chromatids.