What vitamin is needed for Calcium absorption?

Which of the following is not used to classify a virus?

Which capsid shape has many triangular-shaped sides that are roughly in the shape of a sphere?  

Which is a similarity in the replication of DNA viruses and retroviruses?

When co-repressors bind to operon repressor protein, the repressor protein then binds to the promoter.

What event determines that a bacteriophage infection follow the lysogenic pathway or the lytic pathway. 

What choice is a difference between deoxyribonucleotides and ribonucleotides?

Which of the following best describes the difference between photolyase and nucleotide excision DNA repair mechanism?

Of the choices below, which do you think is the most likely outcome if the co-repressor binding site of the tryptophan (trp) repressor was mutated such that the trp repressor could not bind tryptophan?

What is a similarity between the bacteriophage lytic cycle and transduction?