Answer:
Cellular respiration that proceeds in the absence of oxygen is anaerobic respiration. Cellular respiration that proceeds in the presence of oxygen is aerobic respiration. Anaerobic respiration evolved prior to aerobic respiration.
Difference threshold is a minimum alteration in sensory intensity that is noticeable to an observer and can be coded into neural messages. Different threshold is the lowest level of encouragement that is essential to sense that a modification has happened the difference in the intensity between two stimuli that is necessary to yield a just notable difference also known as JND. The just notable difference depends not only on the intensity of the new stimulus but also on the level of stimulation already present which is the more intense the existing stimulus the larger the change must be to be noticeable.
The statement above is FALSE. In the scenario given above the doctor is working at the organ level. This is because, he is working with lung which is an organ that participates in breathing. The lung is an organ because it is made up of different tissues which are in turn made up of different cells.
Working at the cellular level involve working with cells. For instance, when a microbiologist is growing a cell in a culture, he is working at a cellular level.