Is there enzymes present when yeast undergoes respiration? Does ethanol produce affect the rate of respiration?
Yes, there are enzymes present. Yeast cells secrete Amylase which is basically an enzyme which converts starches into sugars; which the yeast can then readily use to respire. Ethanol does affect the rate of cellular respiration, but if you were making bread for example you would not notice this, whereas in alcohol fermentation most yeasts tend to slow ethanol production around 13% die off at around 15% alcohol by volume, but this is dependent on which yeast species is being used.
