In chickens, comb shape is determined by alleles at two loci (R, r and P, p). A walnut comb is produced when at least one dominant allele R is present at one locus and at least one dominant allele P is present at a second locus (genotype R_ P_). A rose comb is produced when at least one dominant allele is present at the first locus and two recessive alleles are present at the second locus (genotype R_pp). A pea comb is produced when two recessive alleles are present at the first locus and at least one dominant allele is present at the second (genotype rrP_). If two recessive alleles are present at the first and at the second locus (rrpp), a single comb is produced. Which of the following cross would produce ½ walnut and ½ pea comb ?

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#Question id: 13168

#Unit 10. Ecological Principles

Use the following diagram from the text showing the spread of the cattle egret, Bulbulcus ibis, since its arrival in the New World, to answer the following question.

How would an ecologist likely explain the expansion of the cattle egret?

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#Question id: 3349

#Unit 11. Evolution and Behavior

Which of these evolutionary agents is most consistent at causing populations to become better suited to their environments over the course of generations?

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#Question id: 1068

#Unit 4. Cell Communication and Cell Signaling

The best-known examples of viruses that cause latent infections are

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#Question id: 10859

#Unit 10. Ecological Principles

Plants that depend upon ants to spread their seeds

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#Question id: 17812

#Unit 7. System Physiology – Animal

The body's main stress hormone is ______.