1.) what is the optimal pH for pepsin? where is pepsin found? 2.) what is the optimal pH for salivary amylase? what substrate does it act on? where is it found?

Which best describes how the common cold spreads in the human body? a bacteria burst out of normal cells killing them b viruses replicate inside respiratory cells c bacteria inject dna into normal cells d viruses insert dna into bacteria

Which statement describes john tuzo wilson’s contribution to the theory of plate tectonics?

1. which of the following transport mechanisms utilizes energy? a. osmosis b. diffusion c. facilitated diffusion d. endocytosis