Question

Photosynthesis is responsible for the release of oxygen in the atmosphere.
a) True
b) False

Answer 1

Hint: All organisms take oxygen while breathing and use it in breaking down glucose molecules for energy. The major source of oxygen on Earth is biological production by the autotrophic organisms.

Complete answer:
Oxygen is returned to the atmosphere mainly by photosynthesis which is done by photosynthetic autotrophic organisms like green plants. This is a part of the oxygen cycle of the Earth.
The process of Photosynthesis produces sugars which heterotrophs use as food and free oxygen to be used by all organisms. The reaction involving this process is
$6{ CO }_{ 2 }+6{ H }_{ 2 }O\xrightarrow [ energy ]{ } { C }_{ 6 }{ H }_{ 12 }{ O }_{ 6 }+6{ CO }_{ 2 }$
Photosynthetic organisms include green plants as well as phytoplankton, Cyanobacteria, etc.
The oxygen cycle refers to the biochemical transition of oxygen atoms between different states through certain reactions and processes between the reservoirs of the Earth. Different reservoirs of oxygen are the atmosphere, biosphere, hydrosphere, and lithosphere. The atmosphere contains $20.9\%$, the biosphere $22\%$, the hydrosphere $33\%$, and the lithosphere contains $46.6\%$ oxygen in them. The sources are mainly biological production by Photosynthesis but abiotic production by photolysis is also seen. The consumption occurs by respiration and decay.

So, the correct answer is option a) True.

Note:
The above picture shows the oxygen cycle on the earth's surface. The four main reservoirs are the biosphere, lithosphere, atmosphere, and hydrosphere, and the major fluxes are shown in arrows. The net value of oxygen produced by Photosynthesis is estimated through the variation in the abundance and isotopic composition of oxygen in the atmosphere.