At some point in their lives, all chordates have:
A) jaws.
B) a brain.
C) a ventral nerve cord.
D) gills.
E) a dorsal nerve cord.
Answer: E
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The production of random evolutionary changes in small breeding populations is known as
a. gene flow. b. genetic drift. c. disruptive selection. d. mutation. e. natural selection.
The site of crossing over is called a _______
Fill in the blank(s) with the appropriate word(s).
Which of the following events will occur in response to gravitropism?
A. The guard cells will swell with water due to an increase in sodium ions which will cause the plant to grow upright. B. Because of the change in the plant's position, it will have sediments of statoliths (amyloplasts containing starch granules) settle towards the lower side of the stems and roots and come into contact with the cytoskeletal elements. C. The stems on the shady side of the plant will elongate due to the presence of auxin. D. The tendril of the plant will coil around any type of substrate that it comes into contact with.
Why are cells arrested at metaphase in the preparation of a karyotype?
a. The chromosomes have duplicated, making them easier to visualize. b. All of the sister chromatids have separated into two new daughter cells. c. All of the chromosomes are at their least condensed state and are easy to visualize. d. All of their chromosomes are highly condensed and easy to visualize.