<u><em>true </em></u>18. ATP is a source of usable energy for the cells.
the bond between the 2nd and 3rd phosphate group is broken to release energy
<u><em>true </em></u>19. ATP is made during photosynthesis.
in the light dependent reactions of the photosynthesis the hydrogen protons pumped in during the electron transport chain are used to synthesize ATP
<u><em>true</em></u>20. ATP is made during respiration.
during anaerobic resipiration and aerobic respiration ATP is produced
<u><em>false</em></u>21. ATP is a waste product of respiration and photosynthesis.
ATP is not a waste product, it plays an important role in photosyntheis, the main role of respiration is ATP production
<u><em>true</em></u> 22. Photosynthesis and respiration form a cycle.
since the reaction of photosynthesis is
6CO2+6H2O-->C6H12O6+6O2
and the reaction of respiration is
C6H12O6+6O2-->6CO2+6H20
you can see that the producs of photosynthesis are used in aerobic respiration and the products of aerobic respiration are used in photosynthesis so the two form a cycle