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 pure-breeding rose comb (RR pp) with a
pure-breeding pea comb (rr PP).
(b) Give the phenotypic results of a cross of Rr Pp ? rr Pp.
(c) Give the phenotypic results of a cross of RR Pp ? rr Pp.
(d) Give the phenotypic results of a cross of Rr pp ? rr Pp.
(e) Give the phenotypic results of a cross of Rr Pp ? rr pp. What will be an ideal response?
(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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A colleague insists on using inexpensive plastic flasks for experiments, which she claims has never been a problem until her most recent carbohydrate hydrolysis tests. After adding enzymes to a solution containing a polymer reactant, she took a short break, then came back to find all of her flasks melted and her experiment ruined. Your colleague suspects sabotage, but you realize immediately that the answer is much simpler. Why did the flasks melt?
a. Plastic is a polymer, and the addition of an enzyme to the carbohydrate solution was sufficient to reduce the plastic flasks into their base monomers. b. Hydrolysis reactions require significant energy input to break polymer bonds; she melted her flasks by leaving them unsupervised over lit Bunsen burners. c. Hydrolysis reactions release energy when polymer bonds are broken. The addition of an enzyme catalyst accelerated the reaction, producing enough waste heat to melt the flasks. d. Carbohydrate solutions are breeding grounds for microorganisms that metabolize plastic; even in a laboratory environment, plenty of microbes would exist to devour the flasks from within.
Imagine that you are conducting experiments and you have a cell line that responds to an external hormonal signal by entering the apoptotic pathway. How would these cells respond to this hormonal signal if you could instantly and completely inactivate the Bcl-2 protein?
a) none of the choices is correct b) Since Bcl-2 normally protects cells from apoptosis, loss of this protein would prevent apoptosis. c) Since Bcl-2 normally promotes apoptosis, loss of this protein would prevent apoptosis. d) Since Bcl-2 normally protects cells from apoptosis, loss of this protein would cause these cells to go through apoptosis.
A shift in weather patterns causes a drought. The normally moist forest becomes dry, with the leaf litter on the forest floor blowing away in high winds. The creek, which normally overflows and floods the forest floor every time it rains, dries up
What would you expect to happen to the slime molds that live in the area? A) The slime mold would begin making red photosynthetic pigments. B) The slime molds would shift from the plasmodium and form fruiting bodies. C) The slime mold would begin parasitizing humans. D) Dry conditions would encourage the slime mold to photosynthesize. E) The plasmodium would expand and colonize the now-clean forest floor.
Which of the following is part of the structure of the mitochondria of a eukaryotic cell?
A) cilia B) cristae C) thylakoids D) inclusions E) nucleolus