You are interested in a new type of autosomal dominant mutation that gives purple eyes in Drosophila. You have a true-breeding purple-eyed line carrying a mutation that you call pr-1. You have isolated a second purple-eyed mutation that you call pr-2, which you have established in a true-breeding line that also carries a recessive marker st, which gives stubby legs. You cross a fly from the pr-1 line to a fly from the st, pr-2 line producing F1 females which you then cross to males from a true breeding st line (normal eyes). From this cross, 1000 progeny flies can be categorized into four different phenotypic classes:

                             

Normally, 3-factor crosses give eight different phenotypic classes, why does this particular cross give only four?

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#Question id: 8933

#Unit 9. Diversity of Life Forms

At which developmental stage should one be able to first distinguish a diploblastic embryo from a triploblastic embryo?

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#Question id: 11148

#Unit 7. System Physiology – Animal

Which of the following ions is most likely to cross the plasma membrane of a resting neuron?

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#Question id: 9616

#Unit 9. Diversity of Life Forms

Which mutation should least require realignment of homologous regions of a gene that is common to several related species?

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#Question id: 19102

#Unit 6. System Physiology – Plant

Phytoplasmas are specialized bacteria that are obligate parasites of the phloem tissue. They are mainly spread by these insects except;

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#Question id: 2318

#Unit 2. Cellular Organization

What plant organelle serves a function similar to that of animal lysosomes?