Why weren’t plants the first form of life to appear on earth?
What will be an ideal response?
Some 2.2 billion years ago, free oxygen was present in the atmosphere. Living things used this reactive substance,
not decaying plant material, in biochemical functions of their cells. The free oxygen in the atmosphere also
produced a layer of ozone, which filters out the ultraviolet light from the sun that is harmful to life.
You might also like to view...
Two light bulbs are wired in series and one bulb burns out (opens.) Technician A says that the other bulb will still work. Technician B says that the current will increase in the circuit because one electrical load (resistance) is no longer operating. Which technician is correct?
A) Technician A only B) Technician B only C) Both technicians A and B D) Neither technician A nor B
The practice of using a cooling coil with higher capacity than the condensing coil (mix-matching) is used in
areas with _____. a. high humidity b. low humidity c. low humidity and high dry-bulb temperatures d. low humidity and low dry-bulb temperatures
How many time constants will it take to completely collapse an inductor's magnetic field?
A) 5 B) 4 C) 1 D) 3
The formula for total voltage in a parallel circuit is ____.
A. ET = ER1 = ER2 = ER3 ... = ERn B. ET = ER1 + ER2 + ER3 ... + ERn C. 1/ET = 1/ER1 + 1/ER2 + 1/ER3 ... + 1/ERn D. ET = ER1 - ER2 - ER3 ... - ERn