In poultry, the genes for rose comb (R) and pea comb (P) produce walnut whenever they occur together (R__ P__);
single-combed individuals have the homozygous condition for both genes (rr pp).
(a) Give the F1 and F2 phenotypic results of a cross of a true-breeding rose comb (RR pp) with a
true-breeding pea comb (rr PP).
(b) Give the phenotypic results of a cross of Rr Pp x rr Pp.
(c) Give the phenotypic results of a cross of RR Pp x rr Pp.
(d) Give the phenotypic results of a cross of Rr pp x rr Pp.
(e) Give the phenotypic results of a cross of Rr Pp x rr pp. What will be an ideal response?
ANSWER: (a) F1: Rr Pp walnut; F2: 9 R__P__ walnut, 3 R__pp rose, 3 rr P__ pea, 1 rr pp single
(b) 3/8 walnut, 3/8 pea, 1/8 rose, 1/8 single
(c) 3/4 walnut, 1/4 rose
(d) 1/4 walnut, 1/4 rose, 1/4 pea, 1/4 single
(e) 1/4 walnut, 1/4 rose, 1/4 pea, 1/4 single
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Why do Rh-negative but not Rh-positive mothers sometimes have babies with hemolytic disease of the newborn?
A. This disease results when an Rh-negative mother's immune system is primed multiple times to produce anti-Rh IgG antibodies that can cross the placenta. If the mother is Rh-positive, she won't produce any anti-Rh antibodies at all. B. Rh-positive mothers produce IgM antibody, not IgG. This antibody can't cross the placenta, so it can't cause hemolytic disease of the newborn. C. Rh-positive mothers will receive a preventative shot from their physician prior to conception. This will provide the protection the fetus needs AFTER conception to avoid the disease. D. Rh-negativity is also associated with hyperproduction of antibodies. As such, Rh-negative mothers are more likely than Rh-positive mothers to produce the antibodies needed to produce this disease.
Systemin can correctly be described as a(n)
A. peptide. B. apoplast. C. receptor. D. leaf lipid. E. carbohydrate.
Radioactive isotopes have
a. excess electrons. b. excess protons. c. excess neutrons. d. insufficient neutrons. e. insufficient protons
Which of the following animals lack a "true"
coelom?
a. flatworms only b. annelids only c. roundworms only d. flatworms and annelids e. flatworms and roundworms