The function of the iris is to ____
a. control the amount of light entering the eye
b. focus the image on the retina
c. respond to particular colors
d. keep the lens under tension to allow for image focusing
e. prevent light scattering upon entry to the eye
ANSWER: a
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Review the experiments by Kohler and Lipton described in Fig. 9.5. What is the key difference between blood serum and blood plasma that affects their ability to help fibroblasts grow in culture?
A. Serum contains more platelet cells than plasma, and platelet cells promote cell growth. B. Molecules found in serum promote cell growth; these molecules are not found in plasma. C. Plasma contains more platelet cells than serum, and platelet cells inhibit cell growth. D. Molecules found in plasma inhibit cell growth; these molecules are not found in serum.
What two organelles are both responsible for converting energy into forms that can be used by cells?
a. ribosomes and chloroplasts b. lysosomes and chloroplasts c. mitochondria and lysosomes d. mitochondria and peroxisomes e. mitochondria and chloroplasts
Aerobic bacteria in the genus ________ are important environmental decomposers, able to digest herbicides like Agent Orange and polychlorinated biphenyls (PCBs)
A) Burkholderia B) Coxiella C) Pseudomonas D) Prevotella E) Hafnia
One difference between sieve-tube cells and vessels is that sieve-tube cells are ________, but vessels are dead.
A. more spherical B. alive C. nucleated D. placed end to end E. hollow