What percentage of the species that have ever lived have become extinct?
a. 1 percent
b. 9 percent
c. 50 percent
d. 75 percent
e. 99 percent
ANSWER: e
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In both plant cells and animal cells, where do the microtubles of the mitotic spindle originate?
a. in the centromere b. in the organizing centres c. in the chromatid d. in the centriole
Which of the following is not true about Methylococcus and Methylomonas?
A. They contain complex arrays of intracellular membranes when using methane. B. Most species are capable of forming cysts. C. They are strict anaerobes. D. All of the choices are correct.
Explain the process of phototropism, including the role of auxin in this process
What will be an ideal response?
Consider the figure illustrating the two major classes of hormones and their actions. Which class of hormones would you expect to be ideally suited for long-term processes such as growth and development?
A) protein hormones, because they can relay messages B) steroid hormones, because they can turn specific genes on or off C) protein hormones, because they cannot cross cell membranes D) steroid hormones, because they can diffuse across cell membranes