Extinction occurs when the environment
changes and
(1) a species can reproduce successfully
(2) an individual has adaptive characteristics
insufficient to allow survival
(3) all members of a species are no longer living
(4) one individual produces some offspring that
evolve into a new species

Which of the following statements about protists are true? a.they are typically found in moist environments. b.they are all unicellular. c.they have a nucleus. d.they are all multicellular.

Which type of respiration takes place when there is no oxygen present? a. anaerobic b. mitochondrial c. cellular d. aerobica. anaerobic

Ivan is looking at a cross section of a stem taken from a vascular plant. he sees two different types of vascular tissue: the xylem, which is closer to the center of the stem, and the phloem, located around the xylem, closer to the outside of the stem. how do these two structures work together in a living plant?