A nerve cell membrane exhibits an all-or-none response to excitation: that is, the magnitude of the response is independent of the magnitude of the stimulus once a threshold value is exceeded. a) Explain in your own words why this is so. b) If every neuron exhibits an all-or-none response, how do you suppose the nervous system of an animal can distinguish different intensities of stimulation

Salmonella typhimurium is a food-borne bacterial pathogen that can cause severe gastrointestinal disease. salmonella is often phagocytosed by macrophages that normally destroy bacterial pathogens, but this bacterium is somehow able to prevent the complete maturation of phagolysosomes. salmonella is able to tolerate the low ph of phagolysosomes, and in fact responds to the drop in ph by secreting toxins that interfere with other cellular responses. which of the following differences would you expect to contribute to the survival of a bacterium within an salmonella-containing phagosome, compared to a healthy phagolysosome? decreased activity of acid hydrolases increased activity of acid hydrolases decreased import of h+ ions increased import of h+ ions my guess is decreased activity of acid hydrolases but i'm not sure.

Idont understand by supporting the plant and holding the leaves up to the light. question 3 options: tap or fibrous root flower petals herbaceous or wood stems leaves with stomata

How does human environment effect the biosphere