During the second trimester of pregnancy, where is the predominant site of red blood cell production?

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#Question id: 1809

#Unit 4. Cell Communication and Cell Signaling

Which of the following statements is TRUE of αβ T-cells?

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#Question id: 20408

#Unit 3. Fundamental Processes

Mutations occur at the same rate in both exons and introns, but 

a) If unwanted mutations occur at exons they are conserved more effectively by selection

b) Exons are negatively selected when undergo mutation

c) Introns may more freely accumulate point substitutions and other changes due to no selection pressure. 

d) exon mutations are eliminated more effectively by selection.

Which of the above is true regarding introns and exons 

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#Question id: 10865

#Unit 10. Ecological Principles

In the Lotka-Volterra model of competition, coexistence between species 1 and species 2

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#Question id: 5527

#Unit 5. Developmental Biology

Ectoderm cells related with anterior neural crest cells condense and form

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#Question id: 15843

#Unit 8. Inheritance Biology

You have isolated two temperature-sensitive mutations in phage l that you suspect may be in the same gene. These phage mutants are called ts-1 and ts-2. Each mutant will form plaques at 35˚C but not at 42˚C. You cross ts-1 to ts-2 phage by coinfecting E. coli at the permissive temperature of 35˚C. When the resulting phage lysate is plated at 35˚C you count 10,000 plaques per ml of phage lysate, but when the same phage lysate is plated at 42˚C, there are only 80 plaques per ml.           What is the distance between the ts-1 and ts-2 mutations in m.u.?