During chick development, the elongation of the primitive streak coextensive with_______

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#Question id: 15834

#Unit 8. Inheritance Biology

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: 23860

#Unit 13. Methods in Biology

RNAi methodology uses double-stranded pieces of RNA to trigger a breakdown or blocking of mRNA. For which of the following might it more possibly be useful?

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#Question id: 1866

#Unit 4. Cell Communication and Cell Signaling

What does HIV binds to?

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#Question id: 10682

#Unit 10. Ecological Principles

if 30 individuals of species 2 take up the same amount of resources as 5 individual of species 1 then the per capita competitive effects on species 1 of species 2 is

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#Question id: 2391

#Unit 2. Cellular Organization

Which organelle is the primary site of ATP synthesis in eukaryotic cells?