During natural processes, heat transfer is always from:

Which of the following spheres is composed exclusively of water?

The level of the atmosphere with the highest temperatures is the:

Which of the following is the MOST important atmospheric component with regard to the earth’s climate and the formation of weather systems?

The atmosphere is heated chiefly by radiation emitted from the earth’s surface.

Multiple choice: Epithelial surfaces provide the first line of defense against infection by the use of several types of mechanisms. One of the chemical mechanisms used by epithelia is

Which complement component is common to both alternate and classical pathways?

C5b6789 is the membrane attack complex when complement is activated

C3 convertase cleaves C3 in blood plasma, leading to a conformational change in the C3b fragment that exposes its reactive thioester group. The activated C3b is potentially harmful to the host, if it becomes covalently attached to a host cell, rather than to the surface of a pathogen. This deleterious outcome is largely avoided by:

The alternative pathway of complement activation has an important role in innate immunity, due to its ability to greatly amplify the amount of C3b deposited onto the pathogen surface. This amplification occurs because: