At sea level, what percentage of the air we breathe is oxygen?
a. 21%
b. 30%
c. 50%
d. 79%
e. 100%
ANSWER: a
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Consider the following mtDNA sequences obtained from chimpanzee and humans in the following geographic regions: Chimp: ATGCGCATTCAATG China: ATGGGCTTTCAATC Ethiopia: ATGGGCATTCAATC England: ATGGGCTTTCAATC Kenya: ATGGGCATTCAATA
Which of the following statements is NOT correct: A. These data depict a higher level of sequence divergence between human and chimp than is to be expected based on overall levels of genetic similarity between human and chimp. B. These data are consistent with the multiregional hypothesis for the origin of humans because the Asian and European sequences are more closely related to each other than either is to the African sequences. C. These data are consistent with an "out of Africa" hypothesis for the origin of humans because the Kenya and Ethiopian samples exhibit an ancestral character state at position 7. D. The African sequences represent older evolutionary lineages than the European sequences because they have one polymorphic site.
The main role of myoglobin in muscle fibers is to ____
a. magnify responses to neurotransmitters b. sequester ions c. synthesize ATP d. store oxygen e. enhance the strength of the power stroke
Cystic fibrosis, which is usually lethal before reproductive ages, is a homozygous recessive disease. Why do cases continue to arise, even though people with the disease rarely live to reproduce?
A. Individuals can pass on the alleles in non-genetic ways, including through the sharing of needles. B. The harmful allele can reside in heterozygous individuals with few to no negative effects. C. Mosquitoes can transfer the disease from person to person. D. Cystic fibrosis is a multifactorial disorder, and is probably controlled by the action of many genes.
The largest reservoir of freshwater is the
a. atmosphere. b. glaciers. c. lakes and rivers. d. ocean.