Many rickettsia are PATHOGENS.
Pathogens are micro organism that cause diseases and rickettsia are majorly disease causing organisms. They are rod shaped bacteria and most species are gram negative. They are natural parasite of some arthropods and they cause diseases in both humans and animals.
Because sugar is not a long lasting condiment
The heart must beat faster during exersise because by increasing the heart rate the body is able to increase cardiac output and deliver the necessary blood flow to the mucles
