Why do members of long-established, high-altitude populations not experience the dizziness, disorientation, and breathlessness associated with altitude sickness?
What will be an ideal response?
High altitude populations have adaptations to compensate for the lower level of oxygen molecules in air. For example, populations from the Andean plateau have an unusually high
concentration of hemoglobin in their blood, a trait that allows them to maximize the amount of oxygen they acquire from each breath. On the other hand, Tibetan plateau dwellers maintain a low hemoglobin level, but take more breaths per minute. Tibetans also make more nitric oxide. This gas encourages blood vessels to widen, increasing blood flow through lung capillaries.
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Which of the following is NOT a specialized function of one or more regions of the digestive tract?
A. food storage B. aerobic metabolism C. chemical breakdown D. absorption of nutrients E. elimination of waste products
Which cells in the root have a suberin layer called the Casparian strip?
A. endodermis B. pericycle C. cortex D. epidermis E. root hair
The oral contraceptive pill contains
a. estrogen only. b. estrogen and progesterone. c. estrogen and follicle-stimulating hormone. d. follicle-stimulating hormone and progesterone. e. estrogen, progesterone, and follicle-stimulating hormone.
In DNA replication, a primer is _____
a. what the original DNA strands are called b. an enzyme that breaks the hydrogen bonds between base pairs c. a short piece of nucleic acid that serves as an attachment point for DNA polymerase
d. a molecule that provides the energy for nucleotide attachments e. a regulatory protein that turns on the gene that starts DNA replication