Explain the effect of temperature and pH on enzyme action.

Needs to be done ASAP.

enzymes loose their form in both unsuitable ph and temprature.

Explanation:

at very high tempratures enzyme molecules denatures due to high speed movements, at low tempratures enzymes works too slow to be useful enough.

low ph solotions contain lot of H+  and high ph solutions have few H+ , and the number of these H+ ions have polar effects on enzymes.  some Enzymes like pepsin works perfect in acidic environment ( ph=2)  while others might work at  high ph  or average ph( like Trypsin  works well at ph=7).

the answer that best describes the relative refractory period in the neuron is the resting membrane potential is restored, but concentrations of sodium and potassium are not restored to their original state.

the refractory period is the time during which another stimulus given to the neuron will not lead to a second potential. thus, because na+ channels are inactivated during this time, additional depolarizing stimuli do not lead to new action potentials.  

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parasites can detrimentally affect their host, but also must not allow their host to die before they can complete their life cycle. some parasites have complex life cycles with many different hosts, and have had to find ways of persisting in many different environments during the change from one host to another. ectoparasites live outside the body of the host, and can more easily  disperse, but are  more exposed to predators, parasites, parasitoids. endoparasites live inside the body of the host, and are therefore protected from the outside environment. but they can be  attacked by the host's immune system. they have therefore developed  mechanisms for dispersal such as  complex life cycles.