Some deer mice are physiologically adapted to live at high altitudes because ____
a. adults maintain fetal forms of hemoglobin
b. of mutations in hemoglobin that increase its oxygen-binding affinity
c. of mutations in myoglobin that increase its oxygen-binding affinity
d. of mutations that increase heart rates
e. of mutations that decrease heart rates
ANSWER: b
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Which of the following terms is used to describe organisms, particularly plants and fungi, that have distinct haploid and diploid phases of their life cycle?
A) polypoloidy B) aneuploidy C) alternation of generations D) asexual propogation E) both choices B and C are correct.
In plant cells, auxin binds to a
a. cell surface receptor and triggers the ras/raf pathway. b. nuclear receptor that changes its shape so that it can bind to and activate genes. c. receptor ubiquitin ligase that stimulates the degradation of transcriptional repressors, resulting in activation of genes. d. cell surface molecule that stimulates fluid uptake.
The life cycle of a zygomycete differs markedly from that of animals because in this fungus, ____.
A. a sexual stage is absent B. mitosis occurs in the haploid growth stage C. there is no fusion of nuclei D. mitosis occurs to produce the haploid reproductive cells E. a diploid stage is absent
Membrane phospholipids
A) have hydrophobic heads that face the center of the membrane and are shielded from water. B) have hydrophilic tails that face outward and are exposed to water. C) are able to drift about in the plasma membrane. D) remain fluid because they are tightly packed against one another.