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#Question id: 5142


The D set of blastomeres is the “organizer” of snail embryos. Experiments have demonstrated that the non-diffusible polar lobe [cortical] cytoplasm that is localized to the D blastomere is extremely important in normal molluscan development.  Which of the following is incorrect?

#Unit 5. Developmental Biology
  1. It contains the determinants for the proper cleavage rhythm and the cleavage orientation of the D blastomere.

  2. It contains certain determinants for autonomous mesodermal and intestinal differentiation.

  3. It is not responsible for permitting the inductive interactions.

  4. If it is transplanted another region of the embryo, secondary axis form.

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#Question id: 5753

#Unit 8. Inheritance Biology

A bacterial histidine mutant was plated on minimal medium and a single colony grew. You decide to sequence the histidine biosynthetic gene of the revertant and discover that the original mutation is still present.  This colony must have been able grow due to a

TLS Online TPP Program

#Question id: 5754

#Unit 8. Inheritance Biology

A cell is exposed to EMS (a mutagen that causes guanine to mispair with thymine) and allowed to undergo a few rounds of DNA replication.  The mutational event caused by this mutagen will be

TLS Online TPP Program

#Question id: 5755

#Unit 8. Inheritance Biology

A researcher studying bacterial toxin predicts that a lysine within the toxin is important for binding it’s target cell.  She used site-directed mutagenesis to change a codon for lysine (AAA) to one for asparagine (AAU).  However, the mutant toxin still binds to its target cell just as well as the wild-type toxin bound and appears to have no other changes. This type of mutation is probably

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#Question id: 5756

#Unit 8. Inheritance Biology

Type of mutation caused by an addition or deletion of a base in a polypeptide-encoding part of a gene

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#Question id: 5757

#Unit 8. Inheritance Biology

A new E. coli mutant was tested for auxotrophy. The mutant grows on:

minimal medium (M) + arginine (A) + proline (P)

M + P + histidine (H)

M + A + H + P

but not on M or on M + A + H. The mutant requires

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#Question id: 5758

#Unit 8. Inheritance Biology

Consider a species with a diploid (2n) number of 28 chromosomes. How many chromosomes would be found in a monoploid body cell?