Match the following prokaryotic classes with differing modes of metabolism with the appropriate descriptions - obligate anaerobes - Facultative anaerobes - Aerotolerant anaerobes - Obligate aerobes A. can shift their metabolism between anaerobic and aerobic modes B. Oxygen-sensitive, can only use anaerobic mode of nutrition C. unable to survive for extended periods in the absence of oxygen. They require oxygen for cellular respiration. D. cannot conduct cellular respiration but are not damaged by oxygen when it is present

- Obligate anaerobes: B

- Facultative anaerobes: A

- Aerotolerant anaerobes: D

- Obligate aerobes: C

Explanation:

Obligate anaerobes are microorganisms that dead in normal atmospheric oxygen (O2) levels (around 21%). Some examples of obligate anaerobes are procaryotic bacteria such as Clostridium, Fusobacterium, Actinomyces and Peptostreptococcus.  Facultative anaerobes are organisms that can grow without O2 and produce energy by fermentation, but they can produce more energy (ATP) by the aerobic respiration mechanism. Facultative anaerobes include both prokaryotic (e.g., Escherichia coli) and eukaryotic (e.g., Saccharomyces cerevisiae) organisms. Aerotolerant anaerobes are microorganisms that can live in O2 atmospheric conditions, but they use fermentation as cellular mechanism to produce energy (ATP). Some examples of aerotolerant anaerobes are lactobacilli and streptococci (bacteria) found in the oral microbiota. Finally, obligate aerobes are organisms that can grow only in normal O2 conditions and metabolize foods through cellular respiration, a process more energetically efficient than fermentation. An example of an obligate aerobe is the human species.

it provides an alternative energy pathway for the reaction to proceed.

a catalyst is a substance that speeds up the rate of a chemical reaction but is not consumed during the course of the reaction.

catalysts increase the rate of reaction without being used up. they do this by lowering the activation energy needed. with a catalyst, more collisions result in a reaction, so the rate of reaction increases. different reactions need different catalysts.

a catalyst works by providing an alternative reaction pathway to the reaction product. the rate of the reaction is increased as this alternative route has a lower activation energy than the reaction route not mediated by the catalyst.