The hormone responsible for cell differentiation, particularly xylem and phloem, in the roots is:
A. gibberellic acid.
B. auxin.
C. ethylene.
D. abscisic acid.
E. cytokinin.
B
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If a trait is inherited in an autosomal recessive fashion, which of the following is not true?
A. Both sexes are equally affected. B. The trait will not occur in offspring if one of the parents is homozygous dominant. C. About one-fourth of the offspring of two heterozygotes will be affected. D. The trait often appears in the progeny of unaffected parents. E. Two affected individuals can have an unaffected child.
Transformation in a cloning experiment is ________
A) ligating pieces of foreign DNA together B) inserting DNA into bacteria cells C) cutting DNA with restriction enzymes D) using PCR to clone a gene E) a technique for determining gene copy number in a genome
Why is apoptosis potentially threatening to the healthy "neighbors" of a dying cell?
A) Cell death would usually spread from one cell to the next via paracrine signals. B) Lysosomal enzymes exiting the dying cell would damage surrounding cells. C) Bits of membrane from the dying cell could merge with neighboring cells and bring in foreign receptors. D) Neighboring cells would activate immunological responses.
Which of the following is an important feature of carbon and that makes life possible?
A. Carbon can form a maximum of 8 covalent bonds. B. Carbon can form a maximum of 6 covalent bonds. C. Carbon can form a maximum of 4 covalent bonds. D. Carbon can form a maximum of 2 covalent bonds. E. None of the choices are possible for carbon.