Answer:
The answer is A.
Explanation:
Adaptive immunity recognizes antigens of viruses.
Answer:
False
Explanation:
Scientist believe that the primitive atmosphere lacked free oxygen. Oxygen is a highly reactive molecule that would have made difficult for complex macromolecules to appear and then create life. Rocks from the precambrian period support this theory.
Anaerobic cells appeared first, then photosynthesis appeared filling the atmosphere with oxygen and the aerobic organism develop cellular respiration to obtain energy, a process more efficient than anaerobic respiration.
Over time, as oxygen levels decrease, CO2 levels increase. Respiration is correct as it uses oxygen as a reactant and releases CO2 as a byproduct.
Non renewable resources can be very expensive, especially in capital outlay. For example, wind energy is very expensive to get started. The batteries alone are a headache. What do you do with those batteries whose life is over? How do you dispose of them? It isn't an easy problem to solve.
Then there's the labor part of wind energy. If they are manufactured in Denver Co and they receive an order from Maine, the blades require a wooden plywood box to be made. Plywood is roughly 20$ a 1/2 sheet (in Canada) to say nothing of the carpenter needed to make the box. I'm told that it takes a good day and one half just to make that box alone. That's for 1 blade. Then there's the shipping cost for 3 blades. Then there's the cost of making the blades which require highly skilled workers.
Then there's the problem of wind, (or lack thereof). the problems just keep on going up and the expenses with them.
B. An oak tree grows from the seed material in an acorn
