Oxygen concentration generally plays an important role in regulating respiration:
a. all the time.
b. never.
c. only when the carbon dioxide concentration falls markedly.
d. only when the oxygen concentration falls markedly.
e. only when the pH falls markedly.
d
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Wheat is a group of grass species. Cultivation originated in the eastern Mediterranean about 10,000 years ago. In comparison to closely related wild grasses, cultivated wheat has shorter stalks and fewer, larger seeds that are firmly attached to the stalk
(e.g., they don't blow away in the wind). How do these changes affect the evolutionary fitness of wheat? A. Fitness is increased because the dispersal of embryos is reduced. B. Fitness is increased because the dispersal is limited. C. Fitness is decreased because more energy is devoted to trying to grow longer stalks. D. Fitness is decreased because the seeds are not dispersed.
Using hair as the derived trait, which does not
fit the clade? a. whale b. crocodile c. wolf d. elephant e. tiger
What is the cloaca?
A. The body opening that serves solely as the exit for wastes from a complete digestive tract B. The second region of the intestine C. A muscular digestive organ that chemically and mechanically breaks down food D. The body opening that serves as the exit for digestive and urinary waste; also functions in reproduction E. The terminal portion of the large intestine
The hypothesis of the viral origin of DNA assumes all of the following EXCEPT which one?
a. The main genetic material of cells in the RNA world was DNA. b. The main genetic material of cells in the RNA world was RNA. c. Viruses horizontally transferred their DNA genomes to cells. d. RNA viruses developed DNA as a mechanism to protect their genomes from destruction by cell ribonucleases.