Evidence of previously existing life is found in
A. viruses.
B. proteins.
C. DNA.
D. fossils.
D. fossils.
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Nitrification of ammonia occurs when ammonia is first converted to nitrite and then is converted to nitrate by the nitrogen-fixing bacteria.
Answer the following statement true (T) or false (F)
The components of fats are fatty acids and
A. amino acids. B. nucleotides. C. phosphate. D. glycerol. E. All of the choices are correct.
What observation did Dr. Katsusaburo Yamagiwa make to lead him to believe that chemicals cause cancer?
A. He observed that cancer rates were 40 times higher in smokers than in nonsmokers. B. He observed that when coal tar extracts were applied to rabbit skin, cancers eventually developed. C. He observed that chimney sweeps exhibited frequent cancer of the scrotum. D. He observed unusual tumors of the nose in snuff users and suggested tobacco as the cause.
Sex-linked conditions are more common in men than in women because
A) men acquire two copies of the defective gene during fertilization. B) men need to inherit only one copy of the recessive allele for the condition to be fully expressed. C) the sex chromosomes are more active in men than in women. D) most genes associated with the sex-linked conditions are linked to the Y chromosome, which determines maleness.