During gastrulation in sea urchins, invagination produces a cavity called the ____
a. archenteron
b. primary mesenchyme
c. secondary mesenchyme
d. blastocoel
e. blastocyst
ANSWER: a
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What would be the most likely outcome if the genetic code was not degenerate?
A. The effect of some mutations would decrease. B. The effect of some mutations would increase. C. The number of stop codons would increase. D. The mutation rate would remain the same.
A characteristic of all cancers is that ____
a. the cells divide continuously b. they have a benign form and a deadly form c. several mutations in several different genes are required in order for cancer to develop d. they are always due to a chromosome disjunction mutation e. the rapid proliferation of cells is required
A mutation results in the loss of the finger-like cell wall ingrowths found in normal placental transfer tissues. What effect is this mutation most likely to have on the development of the embryo?
A. The embryo will develop at a slower rate because the rate of nutrient transfer from mother to embryo will be decreased. B. The embryo will develop too quickly because the rate of nutrient transfer from mother to embryo will be increased. C. The embryo will be unaffected because plant embryos are not dependent on transfer of nutrients from maternal tissues. D. The embryo will be unaffected because the cell wall ingrowths of placental transfer tissues have no effect on nutrient transfer from maternal tissues. E. The embryo will be unable to develop because necessary sugars can no longer be transported across the plasma membrane.
____ discovered the basis for the ____ rule, which states that the amounts of adenine and thymine are identical, as are
the amounts of cytosine and guanine.
a. Avery; base-pair b. Griffith, double helix c. Chargaff; base-pair d. Chase; double helix e. Pauling; base-pair