Answer:
(A) live for many hours and multiply.
Green algae will undergo <u>oxygenetic photosynthesis (</u>non-cyclic photosynthesis oxygen by-product )  under this condition in  their <u>Cytoplasm  </u>instead of <u>chloroplasts in plants,</u> and  instead of anooxygenic photosynthesis(without oxygen by-product) of  bacteria. 
 They absorb light through <u>accessory pigments </u>and pass  this to <u>chlorophyll a and b. </u>The Carbon atom in this process is from inorganic salts <u>H2CO3-, </u>and  which react to form  <u>C02. </u>The latter  diffuses into the algae for the process of photosynthesis.
Naturally this oxygenic photosynthesis is important to algae because  it helps to suppress photo-oxidation.This is because the production of C02  from the inorganic salt, inhibits the activities of Ribulose Biphospate(RuBP), thereby preventing photo-oxodation from taken place.
 In addition, the ability of this organism to raise the C02 concentration level close to the level of enzyme Rubisco by concentrating levels of inorganic carbon than the environmental  C02 of the atmosphere, ensures constant supply of C02 for photosynthesis.  This  carbon (from inorganic salt) is rarely limiting  therefore  improving the efficiency of this photosynthetic  process.
 Thus, the organism undergoes photosynthesis to produce glucose with oxygen as the by-product in the usual green plant fashion .