Why are the first few minutes of a heart attack the most important for giving cpr?

With regard to enzymes, key is to lock as a) substrate is to activation energy eliminate b) product is to substrate. c) enzyme is to active site. d) substrate is to active site.

Up to what percentage of the world's flora consisted of cycads during the triassic period? 100% 75% 50% 20%

Which of the following is not a technology that can be used to conserve resources? a. hydropower b. volcanic power c. natural gas d. geothermal select the best answer from the choices provided a b c d