The process of results in the amplification of particular b cells with specificity for antigen:

Which of the following is a reason why early living organisms on earth could not have survived on the surface? 1. the lack of an ozone layer 2. the lack of oxygen in the atmosphere 3. the fact that these organisms were single-celled

Interferons play a vital role in the immune system why are interferons so important?

Which promotes sustainability? o a. using more landfills o b. finding new sources of coal o c. increasing consumption o d. encouraging recycling programs