Which structure conducts electrical signals from the apex of the heart to the ventricular myocardium, causing the ventricles to contract?
a. arterioles
b. sinoatrial node
c. Purkinje fibers
d. atrioventricular node
c. Purkinje fibers
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A virgin pine forest covers a valley, and one of the inhabitants is a red squirrel species. A large volcanic eruption occurs and separates the valley with a huge lava flow, thus producing two populations of squirrels. What must occur for the two populations of squirrels to be considered separate species?
A. The two squirrel populations must feed on different species of plants. B. The environment must change so that the populations exist in distinct habitats. C. The fur color or other morphological characteristic of the two squirrel populations must become distinct. D. The two squirrel populations must select mates using different behaviors. E. The two squirrel populations must be reproductively isolated. Clarify Question · What is the key concept addressed by the question? · What type of thinking is required? Gather Content · What do you already know about speciation? Choose Answer · Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer? Reflect on Process · Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
Active transport in plant root cells requires that those cells have access to O2. Normally there is enough
O2 available in air pockets in the soil, but flooded soil has very little O2. Thus, unless they have special adaptations, plants in flooded soil effectively have no active transport in their roots. Which of the following should you expect to occur for trees without special adaptations to flooding after several days in flooded soil?
a. excess uptake of water and minerals in the xylem b. wilting of their leaves c. bursting of leaf cells due to excess water flow d. excess water pushed out at the margins of their leaves e. excess uptake of water and minerals in the xylem, and excess water pushed out at the margins of their leaves
The energy to move chromosomes during mitosis is provided by
a. centrioles. b. DNA polymerization. c. migration of the centrosomes. d. formation of the cell plate. e. ATP.
The major force responsible for water transport in plants is
A. water pressure for guard cells B. photosynthesis C. evaporation D. root pressure