What is the difference between between pulmonary artery and pulmonary vein?​

Scientific thinking: what clues about biology might road kill provide?

The trp operon in e. coli regulates genes that code for enzymes required for synthesis of the repressible operon. when tryptophan is not available amino acid tryptophan. the trp operon is a in the environment, the trp repressor protein activeinactiveregulated. therefore, rna polymerase can bind to the genes to begin transcription.

Deer cave cannot support photosynthesis is as not enough sunlight is present. in spite of this, it still has a complex food chain. what is the energy foundation of this food chain?